opt_range.cc 355 KB
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/* Copyright 2000-2008 MySQL AB, 2008 Sun Microsystems, Inc.
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   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; version 2 of the License.
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   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

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/*
  TODO:
  Fix that MAYBE_KEY are stored in the tree so that we can detect use
  of full hash keys for queries like:

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  select s.id, kws.keyword_id from sites as s,kws where s.id=kws.site_id and kws.keyword_id in (204,205);

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*/

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/*
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  This file contains:

  RangeAnalysisModule  
    A module that accepts a condition, index (or partitioning) description, 
    and builds lists of intervals (in index/partitioning space), such that 
    all possible records that match the condition are contained within the 
    intervals.
    The entry point for the range analysis module is get_mm_tree() function.
    
    The lists are returned in form of complicated structure of interlinked
    SEL_TREE/SEL_IMERGE/SEL_ARG objects.
    See check_quick_keys, find_used_partitions for examples of how to walk 
    this structure.
    All direct "users" of this module are located within this file, too.


  PartitionPruningModule
    A module that accepts a partitioned table, condition, and finds which
    partitions we will need to use in query execution. Search down for
    "PartitionPruningModule" for description.
    The module has single entry point - prune_partitions() function.


  Range/index_merge/groupby-minmax optimizer module  
    A module that accepts a table, condition, and returns 
     - a QUICK_*_SELECT object that can be used to retrieve rows that match
       the specified condition, or a "no records will match the condition" 
       statement.

    The module entry points are
      test_quick_select()
      get_quick_select_for_ref()


  Record retrieval code for range/index_merge/groupby-min-max.
    Implementations of QUICK_*_SELECT classes.
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*/

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#ifdef USE_PRAGMA_IMPLEMENTATION
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#pragma implementation				// gcc: Class implementation
#endif

#include "mysql_priv.h"
#include <m_ctype.h>
#include "sql_select.h"

#ifndef EXTRA_DEBUG
#define test_rb_tree(A,B) {}
#define test_use_count(A) {}
#endif

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/*
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  Convert double value to #rows. Currently this does floor(), and we
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  might consider using round() instead.
*/
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#define double2rows(x) ((ha_rows)(x))
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static int sel_cmp(Field *f,uchar *a,uchar *b,uint8 a_flag,uint8 b_flag);
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static uchar is_null_string[2]= {1,0};
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class RANGE_OPT_PARAM;
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/*
  A construction block of the SEL_ARG-graph.
  
  The following description only covers graphs of SEL_ARG objects with 
  sel_arg->type==KEY_RANGE:

  One SEL_ARG object represents an "elementary interval" in form
  
      min_value <=?  table.keypartX  <=? max_value
  
  The interval is a non-empty interval of any kind: with[out] minimum/maximum
  bound, [half]open/closed, single-point interval, etc.

  1. SEL_ARG GRAPH STRUCTURE
  
  SEL_ARG objects are linked together in a graph. The meaning of the graph
  is better demostrated by an example:
  
     tree->keys[i]
      | 
      |             $              $
      |    part=1   $     part=2   $    part=3
      |             $              $
      |  +-------+  $   +-------+  $   +--------+
      |  | kp1<1 |--$-->| kp2=5 |--$-->| kp3=10 |
      |  +-------+  $   +-------+  $   +--------+
      |      |      $              $       |
      |      |      $              $   +--------+
      |      |      $              $   | kp3=12 | 
      |      |      $              $   +--------+ 
      |  +-------+  $              $   
      \->| kp1=2 |--$--------------$-+ 
         +-------+  $              $ |   +--------+
             |      $              $  ==>| kp3=11 |
         +-------+  $              $ |   +--------+
         | kp1=3 |--$--------------$-+       |
         +-------+  $              $     +--------+
             |      $              $     | kp3=14 |
            ...     $              $     +--------+
 
  The entire graph is partitioned into "interval lists".

  An interval list is a sequence of ordered disjoint intervals over the same
  key part. SEL_ARG are linked via "next" and "prev" pointers. Additionally,
  all intervals in the list form an RB-tree, linked via left/right/parent 
  pointers. The RB-tree root SEL_ARG object will be further called "root of the
  interval list".
  
    In the example pic, there are 4 interval lists: 
    "kp<1 OR kp1=2 OR kp1=3", "kp2=5", "kp3=10 OR kp3=12", "kp3=11 OR kp3=13".
    The vertical lines represent SEL_ARG::next/prev pointers.
    
  In an interval list, each member X may have SEL_ARG::next_key_part pointer
  pointing to the root of another interval list Y. The pointed interval list
  must cover a key part with greater number (i.e. Y->part > X->part).
    
    In the example pic, the next_key_part pointers are represented by
    horisontal lines.

  2. SEL_ARG GRAPH SEMANTICS

  It represents a condition in a special form (we don't have a name for it ATM)
  The SEL_ARG::next/prev is "OR", and next_key_part is "AND".
  
  For example, the picture represents the condition in form:
   (kp1 < 1 AND kp2=5 AND (kp3=10 OR kp3=12)) OR 
   (kp1=2 AND (kp3=11 OR kp3=14)) OR 
   (kp1=3 AND (kp3=11 OR kp3=14))


  3. SEL_ARG GRAPH USE

  Use get_mm_tree() to construct SEL_ARG graph from WHERE condition.
  Then walk the SEL_ARG graph and get a list of dijsoint ordered key
  intervals (i.e. intervals in form
  
   (constA1, .., const1_K) < (keypart1,.., keypartK) < (constB1, .., constB_K)

  Those intervals can be used to access the index. The uses are in:
   - check_quick_select() - Walk the SEL_ARG graph and find an estimate of
                            how many table records are contained within all
                            intervals.
   - get_quick_select()   - Walk the SEL_ARG, materialize the key intervals,
                            and create QUICK_RANGE_SELECT object that will
                            read records within these intervals.
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  4. SPACE COMPLEXITY NOTES 

    SEL_ARG graph is a representation of an ordered disjoint sequence of
    intervals over the ordered set of index tuple values.

    For multi-part keys, one can construct a WHERE expression such that its
    list of intervals will be of combinatorial size. Here is an example:
     
      (keypart1 IN (1,2, ..., n1)) AND 
      (keypart2 IN (1,2, ..., n2)) AND 
      (keypart3 IN (1,2, ..., n3))
    
    For this WHERE clause the list of intervals will have n1*n2*n3 intervals
    of form
     
      (keypart1, keypart2, keypart3) = (k1, k2, k3), where 1 <= k{i} <= n{i}
    
    SEL_ARG graph structure aims to reduce the amount of required space by
    "sharing" the elementary intervals when possible (the pic at the
    beginning of this comment has examples of such sharing). The sharing may 
    prevent combinatorial blowup:

      There are WHERE clauses that have combinatorial-size interval lists but
      will be represented by a compact SEL_ARG graph.
      Example:
        (keypartN IN (1,2, ..., n1)) AND 
        ...
        (keypart2 IN (1,2, ..., n2)) AND 
        (keypart1 IN (1,2, ..., n3))

    but not in all cases:

    - There are WHERE clauses that do have a compact SEL_ARG-graph
      representation but get_mm_tree() and its callees will construct a
      graph of combinatorial size.
      Example:
        (keypart1 IN (1,2, ..., n1)) AND 
        (keypart2 IN (1,2, ..., n2)) AND 
        ...
        (keypartN IN (1,2, ..., n3))

    - There are WHERE clauses for which the minimal possible SEL_ARG graph
      representation will have combinatorial size.
      Example:
        By induction: Let's take any interval on some keypart in the middle:

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           kp15=c0
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        Then let's AND it with this interval 'structure' from preceding and
        following keyparts:

          (kp14=c1 AND kp16=c3) OR keypart14=c2) (*)
        
        We will obtain this SEL_ARG graph:
 
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             kp14     $      kp15      $      kp16
                      $                $
         +---------+  $   +---------+  $   +---------+
         | kp14=c1 |--$-->| kp15=c0 |--$-->| kp16=c3 |
         +---------+  $   +---------+  $   +---------+
              |       $                $              
         +---------+  $   +---------+  $             
         | kp14=c2 |--$-->| kp15=c0 |  $             
         +---------+  $   +---------+  $             
                      $                $
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       Note that we had to duplicate "kp15=c0" and there was no way to avoid
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       that. 
       The induction step: AND the obtained expression with another "wrapping"
       expression like (*).
       When the process ends because of the limit on max. number of keyparts 
       we'll have:

         WHERE clause length  is O(3*#max_keyparts)
         SEL_ARG graph size   is O(2^(#max_keyparts/2))

       (it is also possible to construct a case where instead of 2 in 2^n we
        have a bigger constant, e.g. 4, and get a graph with 4^(31/2)= 2^31
        nodes)

    We avoid consuming too much memory by setting a limit on the number of
    SEL_ARG object we can construct during one range analysis invocation.
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*/

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class SEL_ARG :public Sql_alloc
{
public:
  uint8 min_flag,max_flag,maybe_flag;
  uint8 part;					// Which key part
  uint8 maybe_null;
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  /* 
    Number of children of this element in the RB-tree, plus 1 for this
    element itself.
  */
  uint16 elements;
  /*
    Valid only for elements which are RB-tree roots: Number of times this
    RB-tree is referred to (it is referred by SEL_ARG::next_key_part or by
    SEL_TREE::keys[i] or by a temporary SEL_ARG* variable)
  */
  ulong use_count;

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  Field *field;
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  uchar *min_value,*max_value;			// Pointer to range
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  /*
    eq_tree() requires that left == right == 0 if the type is MAYBE_KEY.
   */
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  SEL_ARG *left,*right;   /* R-B tree children */
  SEL_ARG *next,*prev;    /* Links for bi-directional interval list */
  SEL_ARG *parent;        /* R-B tree parent */
  SEL_ARG *next_key_part; 
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  enum leaf_color { BLACK,RED } color;
  enum Type { IMPOSSIBLE, MAYBE, MAYBE_KEY, KEY_RANGE } type;

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  enum { MAX_SEL_ARGS = 16000 };
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  SEL_ARG() {}
  SEL_ARG(SEL_ARG &);
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  SEL_ARG(Field *,const uchar *, const uchar *);
  SEL_ARG(Field *field, uint8 part, uchar *min_value, uchar *max_value,
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	  uint8 min_flag, uint8 max_flag, uint8 maybe_flag);
  SEL_ARG(enum Type type_arg)
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    :min_flag(0),elements(1),use_count(1),left(0),right(0),next_key_part(0),
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    color(BLACK), type(type_arg)
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  {}
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  inline bool is_same(SEL_ARG *arg)
  {
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    if (type != arg->type || part != arg->part)
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      return 0;
    if (type != KEY_RANGE)
      return 1;
    return cmp_min_to_min(arg) == 0 && cmp_max_to_max(arg) == 0;
  }
  inline void merge_flags(SEL_ARG *arg) { maybe_flag|=arg->maybe_flag; }
  inline void maybe_smaller() { maybe_flag=1; }
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  /* Return true iff it's a single-point null interval */
  inline bool is_null_interval() { return maybe_null && max_value[0] == 1; } 
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  inline int cmp_min_to_min(SEL_ARG* arg)
  {
    return sel_cmp(field,min_value, arg->min_value, min_flag, arg->min_flag);
  }
  inline int cmp_min_to_max(SEL_ARG* arg)
  {
    return sel_cmp(field,min_value, arg->max_value, min_flag, arg->max_flag);
  }
  inline int cmp_max_to_max(SEL_ARG* arg)
  {
    return sel_cmp(field,max_value, arg->max_value, max_flag, arg->max_flag);
  }
  inline int cmp_max_to_min(SEL_ARG* arg)
  {
    return sel_cmp(field,max_value, arg->min_value, max_flag, arg->min_flag);
  }
  SEL_ARG *clone_and(SEL_ARG* arg)
  {						// Get overlapping range
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    uchar *new_min,*new_max;
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    uint8 flag_min,flag_max;
    if (cmp_min_to_min(arg) >= 0)
    {
      new_min=min_value; flag_min=min_flag;
    }
    else
    {
      new_min=arg->min_value; flag_min=arg->min_flag; /* purecov: deadcode */
    }
    if (cmp_max_to_max(arg) <= 0)
    {
      new_max=max_value; flag_max=max_flag;
    }
    else
    {
      new_max=arg->max_value; flag_max=arg->max_flag;
    }
    return new SEL_ARG(field, part, new_min, new_max, flag_min, flag_max,
		       test(maybe_flag && arg->maybe_flag));
  }
  SEL_ARG *clone_first(SEL_ARG *arg)
  {						// min <= X < arg->min
    return new SEL_ARG(field,part, min_value, arg->min_value,
		       min_flag, arg->min_flag & NEAR_MIN ? 0 : NEAR_MAX,
		       maybe_flag | arg->maybe_flag);
  }
  SEL_ARG *clone_last(SEL_ARG *arg)
  {						// min <= X <= key_max
    return new SEL_ARG(field, part, min_value, arg->max_value,
		       min_flag, arg->max_flag, maybe_flag | arg->maybe_flag);
  }
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  SEL_ARG *clone(RANGE_OPT_PARAM *param, SEL_ARG *new_parent, SEL_ARG **next);
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  bool copy_min(SEL_ARG* arg)
  {						// Get overlapping range
    if (cmp_min_to_min(arg) > 0)
    {
      min_value=arg->min_value; min_flag=arg->min_flag;
      if ((max_flag & (NO_MAX_RANGE | NO_MIN_RANGE)) ==
	  (NO_MAX_RANGE | NO_MIN_RANGE))
	return 1;				// Full range
    }
    maybe_flag|=arg->maybe_flag;
    return 0;
  }
  bool copy_max(SEL_ARG* arg)
  {						// Get overlapping range
    if (cmp_max_to_max(arg) <= 0)
    {
      max_value=arg->max_value; max_flag=arg->max_flag;
      if ((max_flag & (NO_MAX_RANGE | NO_MIN_RANGE)) ==
	  (NO_MAX_RANGE | NO_MIN_RANGE))
	return 1;				// Full range
    }
    maybe_flag|=arg->maybe_flag;
    return 0;
  }

  void copy_min_to_min(SEL_ARG *arg)
  {
    min_value=arg->min_value; min_flag=arg->min_flag;
  }
  void copy_min_to_max(SEL_ARG *arg)
  {
    max_value=arg->min_value;
    max_flag=arg->min_flag & NEAR_MIN ? 0 : NEAR_MAX;
  }
  void copy_max_to_min(SEL_ARG *arg)
  {
    min_value=arg->max_value;
    min_flag=arg->max_flag & NEAR_MAX ? 0 : NEAR_MIN;
  }
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  /* returns a number of keypart values (0 or 1) appended to the key buffer */
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  int store_min(uint length, uchar **min_key,uint min_key_flag)
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  {
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    if ((min_flag & GEOM_FLAG) ||
        (!(min_flag & NO_MIN_RANGE) &&
	!(min_key_flag & (NO_MIN_RANGE | NEAR_MIN))))
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    {
      if (maybe_null && *min_value)
      {
	**min_key=1;
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	bzero(*min_key+1,length-1);
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      }
      else
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	memcpy(*min_key,min_value,length);
      (*min_key)+= length;
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      return 1;
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    }
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    return 0;
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  }
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  /* returns a number of keypart values (0 or 1) appended to the key buffer */
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  int store_max(uint length, uchar **max_key, uint max_key_flag)
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  {
    if (!(max_flag & NO_MAX_RANGE) &&
	!(max_key_flag & (NO_MAX_RANGE | NEAR_MAX)))
    {
      if (maybe_null && *max_value)
      {
	**max_key=1;
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	bzero(*max_key+1,length-1);
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      }
      else
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	memcpy(*max_key,max_value,length);
      (*max_key)+= length;
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      return 1;
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    }
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    return 0;
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  }

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  /* returns a number of keypart values appended to the key buffer */
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  int store_min_key(KEY_PART *key, uchar **range_key, uint *range_key_flag)
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  {
    SEL_ARG *key_tree= first();
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    uint res= key_tree->store_min(key[key_tree->part].store_length,
                                  range_key, *range_key_flag);
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    *range_key_flag|= key_tree->min_flag;
    if (key_tree->next_key_part &&
	key_tree->next_key_part->part == key_tree->part+1 &&
	!(*range_key_flag & (NO_MIN_RANGE | NEAR_MIN)) &&
	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
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      res+= key_tree->next_key_part->store_min_key(key, range_key,
                                                   range_key_flag);
    return res;
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  }

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  /* returns a number of keypart values appended to the key buffer */
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  int store_max_key(KEY_PART *key, uchar **range_key, uint *range_key_flag)
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  {
    SEL_ARG *key_tree= last();
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    uint res=key_tree->store_max(key[key_tree->part].store_length,
                                 range_key, *range_key_flag);
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    (*range_key_flag)|= key_tree->max_flag;
    if (key_tree->next_key_part &&
	key_tree->next_key_part->part == key_tree->part+1 &&
	!(*range_key_flag & (NO_MAX_RANGE | NEAR_MAX)) &&
	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
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      res+= key_tree->next_key_part->store_max_key(key, range_key,
                                                   range_key_flag);
    return res;
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  }

  SEL_ARG *insert(SEL_ARG *key);
  SEL_ARG *tree_delete(SEL_ARG *key);
  SEL_ARG *find_range(SEL_ARG *key);
  SEL_ARG *rb_insert(SEL_ARG *leaf);
  friend SEL_ARG *rb_delete_fixup(SEL_ARG *root,SEL_ARG *key, SEL_ARG *par);
#ifdef EXTRA_DEBUG
  friend int test_rb_tree(SEL_ARG *element,SEL_ARG *parent);
  void test_use_count(SEL_ARG *root);
#endif
  SEL_ARG *first();
  SEL_ARG *last();
  void make_root();
  inline bool simple_key()
  {
    return !next_key_part && elements == 1;
  }
  void increment_use_count(long count)
  {
    if (next_key_part)
    {
      next_key_part->use_count+=count;
      count*= (next_key_part->use_count-count);
      for (SEL_ARG *pos=next_key_part->first(); pos ; pos=pos->next)
	if (pos->next_key_part)
	  pos->increment_use_count(count);
    }
  }
  void free_tree()
  {
    for (SEL_ARG *pos=first(); pos ; pos=pos->next)
      if (pos->next_key_part)
      {
	pos->next_key_part->use_count--;
	pos->next_key_part->free_tree();
      }
  }

  inline SEL_ARG **parent_ptr()
  {
    return parent->left == this ? &parent->left : &parent->right;
  }
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  /*
    Check if this SEL_ARG object represents a single-point interval

    SYNOPSIS
      is_singlepoint()
    
    DESCRIPTION
      Check if this SEL_ARG object (not tree) represents a single-point
      interval, i.e. if it represents a "keypart = const" or 
      "keypart IS NULL".

    RETURN
      TRUE   This SEL_ARG object represents a singlepoint interval
      FALSE  Otherwise
  */

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  bool is_singlepoint()
  {
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    /* 
      Check for NEAR_MIN ("strictly less") and NO_MIN_RANGE (-inf < field) 
      flags, and the same for right edge.
    */
    if (min_flag || max_flag)
      return FALSE;
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    uchar *min_val= min_value;
    uchar *max_val= max_value;
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    if (maybe_null)
    {
      /* First byte is a NULL value indicator */
      if (*min_val != *max_val)
        return FALSE;

      if (*min_val)
        return TRUE; /* This "x IS NULL" */
      min_val++;
      max_val++;
    }
    return !field->key_cmp(min_val, max_val);
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  }
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  SEL_ARG *clone_tree(RANGE_OPT_PARAM *param);
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};

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class SEL_IMERGE;
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class SEL_TREE :public Sql_alloc
{
public:
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  /*
    Starting an effort to document this field:
    (for some i, keys[i]->type == SEL_ARG::IMPOSSIBLE) => 
       (type == SEL_TREE::IMPOSSIBLE)
  */
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  enum Type { IMPOSSIBLE, ALWAYS, MAYBE, KEY, KEY_SMALLER } type;
  SEL_TREE(enum Type type_arg) :type(type_arg) {}
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  SEL_TREE() :type(KEY)
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  {
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    keys_map.clear_all();
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    bzero((char*) keys,sizeof(keys));
  }
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  SEL_TREE(SEL_TREE *arg, RANGE_OPT_PARAM *param);
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  /*
    Note: there may exist SEL_TREE objects with sel_tree->type=KEY and
    keys[i]=0 for all i. (SergeyP: it is not clear whether there is any
    merit in range analyzer functions (e.g. get_mm_parts) returning a
    pointer to such SEL_TREE instead of NULL)
  */
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  SEL_ARG *keys[MAX_KEY];
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  key_map keys_map;        /* bitmask of non-NULL elements in keys */

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  /*
    Possible ways to read rows using index_merge. The list is non-empty only
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    if type==KEY. Currently can be non empty only if keys_map.is_clear_all().
  */
  List<SEL_IMERGE> merges;
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  /* The members below are filled/used only after get_mm_tree is done */
  key_map ror_scans_map;   /* bitmask of ROR scan-able elements in keys */
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  uint    n_ror_scans;     /* number of set bits in ror_scans_map */
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  struct st_ror_scan_info **ror_scans;     /* list of ROR key scans */
  struct st_ror_scan_info **ror_scans_end; /* last ROR scan */
  /* Note that #records for each key scan is stored in table->quick_rows */
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};

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class RANGE_OPT_PARAM
{
public:
  THD	*thd;   /* Current thread handle */
  TABLE *table; /* Table being analyzed */
  COND *cond;   /* Used inside get_mm_tree(). */
  table_map prev_tables;
  table_map read_tables;
  table_map current_table; /* Bit of the table being analyzed */

  /* Array of parts of all keys for which range analysis is performed */
  KEY_PART *key_parts;
  KEY_PART *key_parts_end;
  MEM_ROOT *mem_root; /* Memory that will be freed when range analysis completes */
  MEM_ROOT *old_root; /* Memory that will last until the query end */
  /*
    Number of indexes used in range analysis (In SEL_TREE::keys only first
    #keys elements are not empty)
  */
  uint keys;
  
  /* 
    If true, the index descriptions describe real indexes (and it is ok to
    call field->optimize_range(real_keynr[...], ...).
    Otherwise index description describes fake indexes.
  */
  bool using_real_indexes;
  
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  bool remove_jump_scans;
  
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  /*
    used_key_no -> table_key_no translation table. Only makes sense if
    using_real_indexes==TRUE
  */
  uint real_keynr[MAX_KEY];
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  /* Number of SEL_ARG objects allocated by SEL_ARG::clone_tree operations */
  uint alloced_sel_args; 
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};
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class PARAM : public RANGE_OPT_PARAM
{
public:
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  KEY_PART *key[MAX_KEY]; /* First key parts of keys used in the query */
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  longlong baseflag;
  uint max_key_part, range_count;
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  uchar min_key[MAX_KEY_LENGTH+MAX_FIELD_WIDTH],
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    max_key[MAX_KEY_LENGTH+MAX_FIELD_WIDTH];
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  bool quick;				// Don't calulate possible keys
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  uint fields_bitmap_size;
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  MY_BITMAP needed_fields;    /* bitmask of fields needed by the query */
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  MY_BITMAP tmp_covered_fields;
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  key_map *needed_reg;        /* ptr to SQL_SELECT::needed_reg */

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  uint *imerge_cost_buff;     /* buffer for index_merge cost estimates */
  uint imerge_cost_buff_size; /* size of the buffer */
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  /* TRUE if last checked tree->key can be used for ROR-scan */
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  bool is_ror_scan;
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  /* Number of ranges in the last checked tree->key */
  uint n_ranges;
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  uint8 first_null_comp; /* first null component if any, 0 - otherwise */
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};
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class TABLE_READ_PLAN;
  class TRP_RANGE;
  class TRP_ROR_INTERSECT;
  class TRP_ROR_UNION;
  class TRP_ROR_INDEX_MERGE;
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  class TRP_GROUP_MIN_MAX;
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struct st_ror_scan_info;

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static SEL_TREE * get_mm_parts(RANGE_OPT_PARAM *param,COND *cond_func,Field *field,
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			       Item_func::Functype type,Item *value,
			       Item_result cmp_type);
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static SEL_ARG *get_mm_leaf(RANGE_OPT_PARAM *param,COND *cond_func,Field *field,
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			    KEY_PART *key_part,
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			    Item_func::Functype type,Item *value);
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static SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param,COND *cond);
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static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts);
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static ha_rows check_quick_select(PARAM *param,uint index,SEL_ARG *key_tree,
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                                  bool update_tbl_stats);
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static ha_rows check_quick_keys(PARAM *param,uint index,SEL_ARG *key_tree,
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                                uchar *min_key, uint min_key_flag, int,
                                uchar *max_key, uint max_key_flag, int);
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QUICK_RANGE_SELECT *get_quick_select(PARAM *param,uint index,
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                                     SEL_ARG *key_tree,
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                                     MEM_ROOT *alloc = NULL);
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static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
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                                       bool index_read_must_be_used,
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                                       bool update_tbl_stats,
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                                       double read_time);
static
TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree,
                                          double read_time,
                                          bool *are_all_covering);
static
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TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
                                                   SEL_TREE *tree,
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                                                   double read_time);
static
TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge,
                                         double read_time);
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static
TRP_GROUP_MIN_MAX *get_best_group_min_max(PARAM *param, SEL_TREE *tree);
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static double get_index_only_read_time(const PARAM* param, ha_rows records,
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                                       int keynr);

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#ifndef DBUG_OFF
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static void print_sel_tree(PARAM *param, SEL_TREE *tree, key_map *tree_map,
                           const char *msg);
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static void print_ror_scans_arr(TABLE *table, const char *msg,
                                struct st_ror_scan_info **start,
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                                struct st_ror_scan_info **end);
static void print_quick(QUICK_SELECT_I *quick, const key_map *needed_reg);
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#endif
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static SEL_TREE *tree_and(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2);
static SEL_TREE *tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2);
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static SEL_ARG *sel_add(SEL_ARG *key1,SEL_ARG *key2);
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static SEL_ARG *key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2);
static SEL_ARG *key_and(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2,
                        uint clone_flag);
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static bool get_range(SEL_ARG **e1,SEL_ARG **e2,SEL_ARG *root1);
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bool get_quick_keys(PARAM *param,QUICK_RANGE_SELECT *quick,KEY_PART *key,
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                    SEL_ARG *key_tree, uchar *min_key,uint min_key_flag,
                    uchar *max_key,uint max_key_flag);
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static bool eq_tree(SEL_ARG* a,SEL_ARG *b);

static SEL_ARG null_element(SEL_ARG::IMPOSSIBLE);
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static bool null_part_in_key(KEY_PART *key_part, const uchar *key,
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                             uint length);
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bool sel_trees_can_be_ored(SEL_TREE *tree1, SEL_TREE *tree2, RANGE_OPT_PARAM* param);
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/*
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  SEL_IMERGE is a list of possible ways to do index merge, i.e. it is
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  a condition in the following form:
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   (t_1||t_2||...||t_N) && (next)
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  where all t_i are SEL_TREEs, next is another SEL_IMERGE and no pair
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  (t_i,t_j) contains SEL_ARGS for the same index.

  SEL_TREE contained in SEL_IMERGE always has merges=NULL.

  This class relies on memory manager to do the cleanup.
*/

class SEL_IMERGE : public Sql_alloc
{
  enum { PREALLOCED_TREES= 10};
public:
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  SEL_TREE *trees_prealloced[PREALLOCED_TREES];
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  SEL_TREE **trees;             /* trees used to do index_merge   */
  SEL_TREE **trees_next;        /* last of these trees            */
  SEL_TREE **trees_end;         /* end of allocated space         */

  SEL_ARG  ***best_keys;        /* best keys to read in SEL_TREEs */

  SEL_IMERGE() :
    trees(&trees_prealloced[0]),
    trees_next(trees),
    trees_end(trees + PREALLOCED_TREES)
  {}
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  SEL_IMERGE (SEL_IMERGE *arg, RANGE_OPT_PARAM *param);
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  int or_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree);
  int or_sel_tree_with_checks(RANGE_OPT_PARAM *param, SEL_TREE *new_tree);
  int or_sel_imerge_with_checks(RANGE_OPT_PARAM *param, SEL_IMERGE* imerge);
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};


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/*
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  Add SEL_TREE to this index_merge without any checks,

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  NOTES
    This function implements the following:
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      (x_1||...||x_N) || t = (x_1||...||x_N||t), where x_i, t are SEL_TREEs

  RETURN
     0 - OK
    -1 - Out of memory.
*/

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int SEL_IMERGE::or_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree)
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{
  if (trees_next == trees_end)
  {
    const int realloc_ratio= 2;		/* Double size for next round */
    uint old_elements= (trees_end - trees);
    uint old_size= sizeof(SEL_TREE**) * old_elements;
    uint new_size= old_size * realloc_ratio;
    SEL_TREE **new_trees;
    if (!(new_trees= (SEL_TREE**)alloc_root(param->mem_root, new_size)))
      return -1;
    memcpy(new_trees, trees, old_size);
    trees=      new_trees;
    trees_next= trees + old_elements;
    trees_end=  trees + old_elements * realloc_ratio;
  }
  *(trees_next++)= tree;
  return 0;
}


/*
  Perform OR operation on this SEL_IMERGE and supplied SEL_TREE new_tree,
  combining new_tree with one of the trees in this SEL_IMERGE if they both
  have SEL_ARGs for the same key.
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  SYNOPSIS
    or_sel_tree_with_checks()
      param    PARAM from SQL_SELECT::test_quick_select
      new_tree SEL_TREE with type KEY or KEY_SMALLER.

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  NOTES
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    This does the following:
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    (t_1||...||t_k)||new_tree =
     either
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       = (t_1||...||t_k||new_tree)
     or
       = (t_1||....||(t_j|| new_tree)||...||t_k),
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     where t_i, y are SEL_TREEs.
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    new_tree is combined with the first t_j it has a SEL_ARG on common
    key with. As a consequence of this, choice of keys to do index_merge
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    read may depend on the order of conditions in WHERE part of the query.

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  RETURN
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    0  OK
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    1  One of the trees was combined with new_tree to SEL_TREE::ALWAYS,
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       and (*this) should be discarded.
   -1  An error occurred.
*/

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int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param, SEL_TREE *new_tree)
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{
  for (SEL_TREE** tree = trees;
       tree != trees_next;
       tree++)
  {
    if (sel_trees_can_be_ored(*tree, new_tree, param))
    {
      *tree = tree_or(param, *tree, new_tree);
      if (!*tree)
        return 1;
      if (((*tree)->type == SEL_TREE::MAYBE) ||
          ((*tree)->type == SEL_TREE::ALWAYS))
        return 1;
      /* SEL_TREE::IMPOSSIBLE is impossible here */
      return 0;
    }
  }

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  /* New tree cannot be combined with any of existing trees. */
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  return or_sel_tree(param, new_tree);
}


/*
  Perform OR operation on this index_merge and supplied index_merge list.

  RETURN
    0 - OK
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    1 - One of conditions in result is always TRUE and this SEL_IMERGE
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        should be discarded.
   -1 - An error occurred
*/

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int SEL_IMERGE::or_sel_imerge_with_checks(RANGE_OPT_PARAM *param, SEL_IMERGE* imerge)
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{
  for (SEL_TREE** tree= imerge->trees;
       tree != imerge->trees_next;
       tree++)
  {
    if (or_sel_tree_with_checks(param, *tree))
      return 1;
  }
  return 0;
}


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SEL_TREE::SEL_TREE(SEL_TREE *arg, RANGE_OPT_PARAM *param): Sql_alloc()
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{
  keys_map= arg->keys_map;
  type= arg->type;
  for (int idx= 0; idx < MAX_KEY; idx++)
  {
    if ((keys[idx]= arg->keys[idx]))
      keys[idx]->increment_use_count(1);
  }

  List_iterator<SEL_IMERGE> it(arg->merges);
  for (SEL_IMERGE *el= it++; el; el= it++)
  {
    SEL_IMERGE *merge= new SEL_IMERGE(el, param);
    if (!merge || merge->trees == merge->trees_next)
    {
      merges.empty();
      return;
    }
    merges.push_back (merge);
  }
}


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SEL_IMERGE::SEL_IMERGE (SEL_IMERGE *arg, RANGE_OPT_PARAM *param) : Sql_alloc()
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{
  uint elements= (arg->trees_end - arg->trees);
  if (elements > PREALLOCED_TREES)
  {
    uint size= elements * sizeof (SEL_TREE **);
    if (!(trees= (SEL_TREE **)alloc_root(param->mem_root, size)))
      goto mem_err;
  }
  else
    trees= &trees_prealloced[0];

  trees_next= trees;
  trees_end= trees + elements;

  for (SEL_TREE **tree = trees, **arg_tree= arg->trees; tree < trees_end; 
       tree++, arg_tree++)
  {
    if (!(*tree= new SEL_TREE(*arg_tree, param)))
      goto mem_err;
  }

  return;

mem_err:
  trees= &trees_prealloced[0];
  trees_next= trees;
  trees_end= trees;
}


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/*
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  Perform AND operation on two index_merge lists and store result in *im1.
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*/

inline void imerge_list_and_list(List<SEL_IMERGE> *im1, List<SEL_IMERGE> *im2)
{
  im1->concat(im2);
}


/*
  Perform OR operation on 2 index_merge lists, storing result in first list.

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  NOTES
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    The following conversion is implemented:
     (a_1 &&...&& a_N)||(b_1 &&...&& b_K) = AND_i,j(a_i || b_j) =>
      => (a_1||b_1).
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    i.e. all conjuncts except the first one are currently dropped.
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    This is done to avoid producing N*K ways to do index_merge.

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    If (a_1||b_1) produce a condition that is always TRUE, NULL is returned
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    and index_merge is discarded (while it is actually possible to try
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    harder).
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    As a consequence of this, choice of keys to do index_merge read may depend
    on the order of conditions in WHERE part of the query.
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  RETURN
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    0     OK, result is stored in *im1
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    other Error, both passed lists are unusable
*/

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int imerge_list_or_list(RANGE_OPT_PARAM *param,
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                        List<SEL_IMERGE> *im1,
                        List<SEL_IMERGE> *im2)
{
  SEL_IMERGE *imerge= im1->head();
  im1->empty();
  im1->push_back(imerge);
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  return imerge->or_sel_imerge_with_checks(param, im2->head());
}


/*
  Perform OR operation on index_merge list and key tree.

  RETURN
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    0     OK, result is stored in *im1.
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    other Error
*/

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int imerge_list_or_tree(RANGE_OPT_PARAM *param,
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                        List<SEL_IMERGE> *im1,
                        SEL_TREE *tree)
{
  SEL_IMERGE *imerge;
  List_iterator<SEL_IMERGE> it(*im1);
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  bool tree_used= FALSE;
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  while ((imerge= it++))
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  {
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    SEL_TREE *or_tree;
    if (tree_used)
    {
      or_tree= new SEL_TREE (tree, param);
      if (!or_tree ||
          (or_tree->keys_map.is_clear_all() && or_tree->merges.is_empty()))
        return FALSE;
    }
    else
      or_tree= tree;

    if (imerge->or_sel_tree_with_checks(param, or_tree))
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      it.remove();
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    tree_used= TRUE;
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  }
  return im1->is_empty();
}
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/***************************************************************************
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** Basic functions for SQL_SELECT and QUICK_RANGE_SELECT
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***************************************************************************/

	/* make a select from mysql info
	   Error is set as following:
	   0 = ok
	   1 = Got some error (out of memory?)
	   */

SQL_SELECT *make_select(TABLE *head, table_map const_tables,
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			table_map read_tables, COND *conds,
                        bool allow_null_cond,
                        int *error)
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{
  SQL_SELECT *select;
  DBUG_ENTER("make_select");

  *error=0;
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  if (!conds && !allow_null_cond)
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    DBUG_RETURN(0);
  if (!(select= new SQL_SELECT))
  {
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    *error= 1;			// out of memory
    DBUG_RETURN(0);		/* purecov: inspected */
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  }
  select->read_tables=read_tables;
  select->const_tables=const_tables;
  select->head=head;
  select->cond=conds;

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  if (head->sort.io_cache)
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  {
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    select->file= *head->sort.io_cache;
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    select->records=(ha_rows) (select->file.end_of_file/
			       head->file->ref_length);
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    my_free(head->sort.io_cache, MYF(0));
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    head->sort.io_cache=0;
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  }
  DBUG_RETURN(select);
}


SQL_SELECT::SQL_SELECT() :quick(0),cond(0),free_cond(0)
{
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  quick_keys.clear_all(); needed_reg.clear_all();
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  my_b_clear(&file);
}


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void SQL_SELECT::cleanup()
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{
  delete quick;
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  quick= 0;
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  if (free_cond)
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  {
    free_cond=0;
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    delete cond;
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    cond= 0;
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  }
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  close_cached_file(&file);
}

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SQL_SELECT::~SQL_SELECT()
{
  cleanup();
}

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#undef index					// Fix for Unixware 7
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QUICK_SELECT_I::QUICK_SELECT_I()
  :max_used_key_length(0),
   used_key_parts(0)
{}

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QUICK_RANGE_SELECT::QUICK_RANGE_SELECT(THD *thd, TABLE *table, uint key_nr,
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                                       bool no_alloc, MEM_ROOT *parent_alloc)
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  :dont_free(0),error(0),free_file(0),in_range(0),cur_range(NULL),last_range(0)
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{
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  my_bitmap_map *bitmap;
  DBUG_ENTER("QUICK_RANGE_SELECT::QUICK_RANGE_SELECT");

  in_ror_merged_scan= 0;
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  sorted= 0;
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  index= key_nr;
  head=  table;
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  key_part_info= head->key_info[index].key_part;
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  my_init_dynamic_array(&ranges, sizeof(QUICK_RANGE*), 16, 16);
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  /* 'thd' is not accessible in QUICK_RANGE_SELECT::reset(). */
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  multi_range_bufsiz= thd->variables.read_rnd_buff_size;
  multi_range_count= thd->variables.multi_range_count;
  multi_range_length= 0;
  multi_range= NULL;
  multi_range_buff= NULL;

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  if (!no_alloc && !parent_alloc)
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  {
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    // Allocates everything through the internal memroot
    init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
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    thd->mem_root= &alloc;
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  }
  else
    bzero((char*) &alloc,sizeof(alloc));
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  file= head->file;
  record= head->record[0];
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  save_read_set= head->read_set;
  save_write_set= head->write_set;

  /* Allocate a bitmap for used columns */
  if (!(bitmap= (my_bitmap_map*) my_malloc(head->s->column_bitmap_size,
                                           MYF(MY_WME))))
  {
    column_bitmap.bitmap= 0;
    error= 1;
  }
  else
    bitmap_init(&column_bitmap, bitmap, head->s->fields, FALSE);
  DBUG_VOID_RETURN;
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}

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int QUICK_RANGE_SELECT::init()
{
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  DBUG_ENTER("QUICK_RANGE_SELECT::init");
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  if (file->inited != handler::NONE)
    file->ha_index_or_rnd_end();
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  DBUG_RETURN(FALSE);
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}


void QUICK_RANGE_SELECT::range_end()
{
  if (file->inited != handler::NONE)
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    file->ha_index_or_rnd_end();
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}

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QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT()
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{
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  DBUG_ENTER("QUICK_RANGE_SELECT::~QUICK_RANGE_SELECT");
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  if (!dont_free)
  {
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    /* file is NULL for CPK scan on covering ROR-intersection */
    if (file) 
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    {
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      range_end();
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      if (head->key_read)
      {
        head->key_read= 0;
        file->extra(HA_EXTRA_NO_KEYREAD);
      }
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      if (free_file)
      {
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        DBUG_PRINT("info", ("Freeing separate handler 0x%lx (free: %d)", (long) file,
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                            free_file));
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        file->ha_external_lock(current_thd, F_UNLCK);
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        file->close();
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        delete file;
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      }
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    }
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    delete_dynamic(&ranges); /* ranges are allocated in alloc */
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    free_root(&alloc,MYF(0));
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    my_free((char*) column_bitmap.bitmap, MYF(MY_ALLOW_ZERO_PTR));
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  }
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  head->column_bitmaps_set(save_read_set, save_write_set);
  x_free(multi_range);
  x_free(multi_range_buff);
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  DBUG_VOID_RETURN;
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}

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QUICK_INDEX_MERGE_SELECT::QUICK_INDEX_MERGE_SELECT(THD *thd_param,
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                                                   TABLE *table)
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  :pk_quick_select(NULL), thd(thd_param)
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{
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  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::QUICK_INDEX_MERGE_SELECT");
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  index= MAX_KEY;
  head= table;
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  bzero(&read_record, sizeof(read_record));
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  init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
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  DBUG_VOID_RETURN;
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}

int QUICK_INDEX_MERGE_SELECT::init()
{
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  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::init");
  DBUG_RETURN(0);
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}

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int QUICK_INDEX_MERGE_SELECT::reset()
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{
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  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::reset");
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  DBUG_RETURN(read_keys_and_merge());
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}

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bool
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QUICK_INDEX_MERGE_SELECT::push_quick_back(QUICK_RANGE_SELECT *quick_sel_range)
{
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  /*
    Save quick_select that does scan on clustered primary key as it will be
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    processed separately.
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  */
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  if (head->file->primary_key_is_clustered() &&
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      quick_sel_range->index == head->s->primary_key)
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    pk_quick_select= quick_sel_range;
  else
    return quick_selects.push_back(quick_sel_range);
  return 0;
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}

QUICK_INDEX_MERGE_SELECT::~QUICK_INDEX_MERGE_SELECT()
{
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  List_iterator_fast<QUICK_RANGE_SELECT> quick_it(quick_selects);
  QUICK_RANGE_SELECT* quick;
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  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::~QUICK_INDEX_MERGE_SELECT");
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  quick_it.rewind();
  while ((quick= quick_it++))
    quick->file= NULL;
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  quick_selects.delete_elements();
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  delete pk_quick_select;
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  /* It's ok to call the next two even if they are already deinitialized */
  end_read_record(&read_record);
  free_io_cache(head);
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  free_root(&alloc,MYF(0));
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  DBUG_VOID_RETURN;
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}

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QUICK_ROR_INTERSECT_SELECT::QUICK_ROR_INTERSECT_SELECT(THD *thd_param,
                                                       TABLE *table,
                                                       bool retrieve_full_rows,
                                                       MEM_ROOT *parent_alloc)
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  : cpk_quick(NULL), thd(thd_param), need_to_fetch_row(retrieve_full_rows),
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    scans_inited(FALSE)
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{
  index= MAX_KEY;
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  head= table;
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  record= head->record[0];
  if (!parent_alloc)
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    init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
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  else
    bzero(&alloc, sizeof(MEM_ROOT));
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  last_rowid= (uchar*) alloc_root(parent_alloc? parent_alloc : &alloc,
                                  head->file->ref_length);
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}

1274

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/*
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  Do post-constructor initialization.
  SYNOPSIS
    QUICK_ROR_INTERSECT_SELECT::init()
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1280 1281 1282 1283 1284
  RETURN
    0      OK
    other  Error code
*/

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int QUICK_ROR_INTERSECT_SELECT::init()
{
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  DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::init");
 /* Check if last_rowid was successfully allocated in ctor */
  DBUG_RETURN(!last_rowid);
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}


/*
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  Initialize this quick select to be a ROR-merged scan.

  SYNOPSIS
    QUICK_RANGE_SELECT::init_ror_merged_scan()
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      reuse_handler If TRUE, use head->file, otherwise create a separate
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                    handler object

  NOTES
    This function creates and prepares for subsequent use a separate handler
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    object if it can't reuse head->file. The reason for this is that during
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    ROR-merge several key scans are performed simultaneously, and a single
    handler is only capable of preserving context of a single key scan.

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    In ROR-merge the quick select doing merge does full records retrieval,
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    merged quick selects read only keys.
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  RETURN
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    0  ROR child scan initialized, ok to use.
    1  error
*/

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int QUICK_RANGE_SELECT::init_ror_merged_scan(bool reuse_handler)
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{
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  handler *save_file= file, *org_file;
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  THD *thd;
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  DBUG_ENTER("QUICK_RANGE_SELECT::init_ror_merged_scan");
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  in_ror_merged_scan= 1;
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  if (reuse_handler)
  {
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    DBUG_PRINT("info", ("Reusing handler 0x%lx", (long) file));
    if (init() || reset())
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    {
      DBUG_RETURN(1);
    }
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    head->column_bitmaps_set(&column_bitmap, &column_bitmap);
    goto end;
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  }

  /* Create a separate handler object for this quick select */
  if (free_file)
  {
    /* already have own 'handler' object. */
    DBUG_RETURN(0);
  }
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  thd= head->in_use;
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  if (!(file= head->file->clone(thd->mem_root)))
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  {
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    /* 
      Manually set the error flag. Note: there seems to be quite a few
      places where a failure could cause the server to "hang" the client by
      sending no response to a query. ATM those are not real errors because 
      the storage engine calls in question happen to never fail with the 
      existing storage engines. 
    */
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    my_error(ER_OUT_OF_RESOURCES, MYF(0)); /* purecov: inspected */
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    /* Caller will free the memory */
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    goto failure;  /* purecov: inspected */
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  }
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  head->column_bitmaps_set(&column_bitmap, &column_bitmap);

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  if (file->ha_external_lock(thd, F_RDLCK))
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    goto failure;
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  if (init() || reset())
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  {
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    file->ha_external_lock(thd, F_UNLCK);
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    file->close();
    goto failure;
  }
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  free_file= TRUE;
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  last_rowid= file->ref;
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end:
  /*
    We are only going to read key fields and call position() on 'file'
    The following sets head->tmp_set to only use this key and then updates
    head->read_set and head->write_set to use this bitmap.
    The now bitmap is stored in 'column_bitmap' which is used in ::get_next()
  */
  org_file= head->file;
  head->file= file;
  /* We don't have to set 'head->keyread' here as the 'file' is unique */
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  if (!head->no_keyread)
  {
    head->key_read= 1;
    head->mark_columns_used_by_index(index);
  }
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  head->prepare_for_position();
  head->file= org_file;
  bitmap_copy(&column_bitmap, head->read_set);
  head->column_bitmaps_set(&column_bitmap, &column_bitmap);

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  DBUG_RETURN(0);

failure:
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  head->column_bitmaps_set(save_read_set, save_write_set);
  delete file;
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  file= save_file;
  DBUG_RETURN(1);
}

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/*
  Initialize this quick select to be a part of a ROR-merged scan.
  SYNOPSIS
    QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan()
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      reuse_handler If TRUE, use head->file, otherwise create separate
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                    handler object.
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  RETURN
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    0     OK
    other error code
*/
int QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan(bool reuse_handler)
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{
  List_iterator_fast<QUICK_RANGE_SELECT> quick_it(quick_selects);
  QUICK_RANGE_SELECT* quick;
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  DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::init_ror_merged_scan");
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  /* Initialize all merged "children" quick selects */
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  DBUG_ASSERT(!need_to_fetch_row || reuse_handler);
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  if (!need_to_fetch_row && reuse_handler)
  {
    quick= quick_it++;
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    /*
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      There is no use of this->file. Use it for the first of merged range
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      selects.
    */
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    if (quick->init_ror_merged_scan(TRUE))
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      DBUG_RETURN(1);
    quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS);
  }
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  while ((quick= quick_it++))
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  {
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    if (quick->init_ror_merged_scan(FALSE))
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      DBUG_RETURN(1);
    quick->file->extra(HA_EXTRA_KEYREAD_PRESERVE_FIELDS);
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    /* All merged scans share the same record buffer in intersection. */
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    quick->record= head->record[0];
  }

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  if (need_to_fetch_row && head->file->ha_rnd_init(1))
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  {
    DBUG_PRINT("error", ("ROR index_merge rnd_init call failed"));
    DBUG_RETURN(1);
  }
  DBUG_RETURN(0);
}

1445

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/*
1447 1448 1449 1450 1451 1452 1453 1454
  Initialize quick select for row retrieval.
  SYNOPSIS
    reset()
  RETURN
    0      OK
    other  Error code
*/

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int QUICK_ROR_INTERSECT_SELECT::reset()
{
  DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::reset");
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  if (!scans_inited && init_ror_merged_scan(TRUE))
    DBUG_RETURN(1);
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  scans_inited= TRUE;
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  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  QUICK_RANGE_SELECT *quick;
  while ((quick= it++))
    quick->reset();
  DBUG_RETURN(0);
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}

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/*
  Add a merged quick select to this ROR-intersection quick select.
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  SYNOPSIS
    QUICK_ROR_INTERSECT_SELECT::push_quick_back()
      quick Quick select to be added. The quick select must return
            rows in rowid order.
  NOTES
    This call can only be made before init() is called.
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  RETURN
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    FALSE OK
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    TRUE  Out of memory.
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*/

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bool
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QUICK_ROR_INTERSECT_SELECT::push_quick_back(QUICK_RANGE_SELECT *quick)
{
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  return quick_selects.push_back(quick);
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}

QUICK_ROR_INTERSECT_SELECT::~QUICK_ROR_INTERSECT_SELECT()
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{
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  DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::~QUICK_ROR_INTERSECT_SELECT");
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  quick_selects.delete_elements();
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  delete cpk_quick;
  free_root(&alloc,MYF(0));
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  if (need_to_fetch_row && head->file->inited != handler::NONE)
    head->file->ha_rnd_end();
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  DBUG_VOID_RETURN;
}

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QUICK_ROR_UNION_SELECT::QUICK_ROR_UNION_SELECT(THD *thd_param,
                                               TABLE *table)
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  : thd(thd_param), scans_inited(FALSE)
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{
  index= MAX_KEY;
  head= table;
  rowid_length= table->file->ref_length;
  record= head->record[0];
  init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
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  thd_param->mem_root= &alloc;
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}

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/*
  Do post-constructor initialization.
  SYNOPSIS
    QUICK_ROR_UNION_SELECT::init()
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  RETURN
    0      OK
    other  Error code
*/

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int QUICK_ROR_UNION_SELECT::init()
{
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  DBUG_ENTER("QUICK_ROR_UNION_SELECT::init");
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  if (init_queue(&queue, quick_selects.elements, 0,
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                 FALSE , QUICK_ROR_UNION_SELECT::queue_cmp,
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                 (void*) this))
  {
    bzero(&queue, sizeof(QUEUE));
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    DBUG_RETURN(1);
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  }
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  if (!(cur_rowid= (uchar*) alloc_root(&alloc, 2*head->file->ref_length)))
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    DBUG_RETURN(1);
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  prev_rowid= cur_rowid + head->file->ref_length;
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  DBUG_RETURN(0);
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}

1542

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/*
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  Comparison function to be used QUICK_ROR_UNION_SELECT::queue priority
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  queue.

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  SYNPOSIS
    QUICK_ROR_UNION_SELECT::queue_cmp()
      arg   Pointer to QUICK_ROR_UNION_SELECT
      val1  First merged select
      val2  Second merged select
*/
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1554
int QUICK_ROR_UNION_SELECT::queue_cmp(void *arg, uchar *val1, uchar *val2)
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{
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  QUICK_ROR_UNION_SELECT *self= (QUICK_ROR_UNION_SELECT*)arg;
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  return self->head->file->cmp_ref(((QUICK_SELECT_I*)val1)->last_rowid,
                                   ((QUICK_SELECT_I*)val2)->last_rowid);
}

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/*
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  Initialize quick select for row retrieval.
  SYNOPSIS
    reset()
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1567 1568 1569 1570 1571
  RETURN
    0      OK
    other  Error code
*/

1572 1573
int QUICK_ROR_UNION_SELECT::reset()
{
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  QUICK_SELECT_I *quick;
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  int error;
  DBUG_ENTER("QUICK_ROR_UNION_SELECT::reset");
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  have_prev_rowid= FALSE;
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  if (!scans_inited)
  {
    List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
    while ((quick= it++))
    {
      if (quick->init_ror_merged_scan(FALSE))
        DBUG_RETURN(1);
    }
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    scans_inited= TRUE;
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  }
  queue_remove_all(&queue);
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  /*
    Initialize scans for merged quick selects and put all merged quick
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    selects into the queue.
  */
  List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
  while ((quick= it++))
  {
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    if (quick->reset())
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      DBUG_RETURN(1);
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    if ((error= quick->get_next()))
    {
      if (error == HA_ERR_END_OF_FILE)
        continue;
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      DBUG_RETURN(error);
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    }
    quick->save_last_pos();
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    queue_insert(&queue, (uchar*)quick);
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  }

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  if (head->file->ha_rnd_init(1))
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  {
    DBUG_PRINT("error", ("ROR index_merge rnd_init call failed"));
    DBUG_RETURN(1);
  }

  DBUG_RETURN(0);
}


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bool
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QUICK_ROR_UNION_SELECT::push_quick_back(QUICK_SELECT_I *quick_sel_range)
{
  return quick_selects.push_back(quick_sel_range);
}

QUICK_ROR_UNION_SELECT::~QUICK_ROR_UNION_SELECT()
{
  DBUG_ENTER("QUICK_ROR_UNION_SELECT::~QUICK_ROR_UNION_SELECT");
  delete_queue(&queue);
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  quick_selects.delete_elements();
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  if (head->file->inited != handler::NONE)
    head->file->ha_rnd_end();
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  free_root(&alloc,MYF(0));
  DBUG_VOID_RETURN;
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}

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QUICK_RANGE::QUICK_RANGE()
  :min_key(0),max_key(0),min_length(0),max_length(0),
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   flag(NO_MIN_RANGE | NO_MAX_RANGE),
  min_keypart_map(0), max_keypart_map(0)
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{}

SEL_ARG::SEL_ARG(SEL_ARG &arg) :Sql_alloc()
{
  type=arg.type;
  min_flag=arg.min_flag;
  max_flag=arg.max_flag;
  maybe_flag=arg.maybe_flag;
  maybe_null=arg.maybe_null;
  part=arg.part;
  field=arg.field;
  min_value=arg.min_value;
  max_value=arg.max_value;
  next_key_part=arg.next_key_part;
  use_count=1; elements=1;
}


inline void SEL_ARG::make_root()
{
  left=right= &null_element;
  color=BLACK;
  next=prev=0;
  use_count=0; elements=1;
}

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SEL_ARG::SEL_ARG(Field *f,const uchar *min_value_arg,
                 const uchar *max_value_arg)
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  :min_flag(0), max_flag(0), maybe_flag(0), maybe_null(f->real_maybe_null()),
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   elements(1), use_count(1), field(f), min_value((uchar*) min_value_arg),
   max_value((uchar*) max_value_arg), next(0),prev(0),
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   next_key_part(0),color(BLACK),type(KEY_RANGE)
{
  left=right= &null_element;
}

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SEL_ARG::SEL_ARG(Field *field_,uint8 part_,
                 uchar *min_value_, uchar *max_value_,
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		 uint8 min_flag_,uint8 max_flag_,uint8 maybe_flag_)
  :min_flag(min_flag_),max_flag(max_flag_),maybe_flag(maybe_flag_),
   part(part_),maybe_null(field_->real_maybe_null()), elements(1),use_count(1),
   field(field_), min_value(min_value_), max_value(max_value_),
   next(0),prev(0),next_key_part(0),color(BLACK),type(KEY_RANGE)
{
  left=right= &null_element;
}

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SEL_ARG *SEL_ARG::clone(RANGE_OPT_PARAM *param, SEL_ARG *new_parent, 
                        SEL_ARG **next_arg)
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{
  SEL_ARG *tmp;
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  /* Bail out if we have already generated too many SEL_ARGs */
  if (++param->alloced_sel_args > MAX_SEL_ARGS)
    return 0;

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  if (type != KEY_RANGE)
  {
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    if (!(tmp= new (param->mem_root) SEL_ARG(type)))
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      return 0;					// out of memory
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    tmp->prev= *next_arg;			// Link into next/prev chain
    (*next_arg)->next=tmp;
    (*next_arg)= tmp;
  }
  else
  {
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    if (!(tmp= new (param->mem_root) SEL_ARG(field,part, min_value,max_value,
                                             min_flag, max_flag, maybe_flag)))
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      return 0;					// OOM
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    tmp->parent=new_parent;
    tmp->next_key_part=next_key_part;
    if (left != &null_element)
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      if (!(tmp->left=left->clone(param, tmp, next_arg)))
	return 0;				// OOM
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    tmp->prev= *next_arg;			// Link into next/prev chain
    (*next_arg)->next=tmp;
    (*next_arg)= tmp;

    if (right != &null_element)
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      if (!(tmp->right= right->clone(param, tmp, next_arg)))
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	return 0;				// OOM
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  }
  increment_use_count(1);
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  tmp->color= color;
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  tmp->elements= this->elements;
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  return tmp;
}

SEL_ARG *SEL_ARG::first()
{
  SEL_ARG *next_arg=this;
  if (!next_arg->left)
    return 0;					// MAYBE_KEY
  while (next_arg->left != &null_element)
    next_arg=next_arg->left;
  return next_arg;
}

SEL_ARG *SEL_ARG::last()
{
  SEL_ARG *next_arg=this;
  if (!next_arg->right)
    return 0;					// MAYBE_KEY
  while (next_arg->right != &null_element)
    next_arg=next_arg->right;
  return next_arg;
}

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/*
  Check if a compare is ok, when one takes ranges in account
  Returns -2 or 2 if the ranges where 'joined' like  < 2 and >= 2
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*/
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static int sel_cmp(Field *field, uchar *a, uchar *b, uint8 a_flag,
                   uint8 b_flag)
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{
  int cmp;
  /* First check if there was a compare to a min or max element */
  if (a_flag & (NO_MIN_RANGE | NO_MAX_RANGE))
  {
    if ((a_flag & (NO_MIN_RANGE | NO_MAX_RANGE)) ==
	(b_flag & (NO_MIN_RANGE | NO_MAX_RANGE)))
      return 0;
    return (a_flag & NO_MIN_RANGE) ? -1 : 1;
  }
  if (b_flag & (NO_MIN_RANGE | NO_MAX_RANGE))
    return (b_flag & NO_MIN_RANGE) ? 1 : -1;

  if (field->real_maybe_null())			// If null is part of key
  {
    if (*a != *b)
    {
      return *a ? -1 : 1;
    }
    if (*a)
      goto end;					// NULL where equal
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    a++; b++;					// Skip NULL marker
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  }
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  cmp=field->key_cmp(a , b);
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  if (cmp) return cmp < 0 ? -1 : 1;		// The values differed

  // Check if the compared equal arguments was defined with open/closed range
 end:
  if (a_flag & (NEAR_MIN | NEAR_MAX))
  {
    if ((a_flag & (NEAR_MIN | NEAR_MAX)) == (b_flag & (NEAR_MIN | NEAR_MAX)))
      return 0;
    if (!(b_flag & (NEAR_MIN | NEAR_MAX)))
      return (a_flag & NEAR_MIN) ? 2 : -2;
    return (a_flag & NEAR_MIN) ? 1 : -1;
  }
  if (b_flag & (NEAR_MIN | NEAR_MAX))
    return (b_flag & NEAR_MIN) ? -2 : 2;
  return 0;					// The elements where equal
}


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SEL_ARG *SEL_ARG::clone_tree(RANGE_OPT_PARAM *param)
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{
  SEL_ARG tmp_link,*next_arg,*root;
  next_arg= &tmp_link;
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  if (!(root= clone(param, (SEL_ARG *) 0, &next_arg)))
    return 0;
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  next_arg->next=0;				// Fix last link
  tmp_link.next->prev=0;			// Fix first link
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  if (root)					// If not OOM
    root->use_count= 0;
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  return root;
}

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/*
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  Find the best index to retrieve first N records in given order
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  SYNOPSIS
    get_index_for_order()
      table  Table to be accessed
      order  Required ordering
      limit  Number of records that will be retrieved

  DESCRIPTION
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    Find the best index that allows to retrieve first #limit records in the 
    given order cheaper then one would retrieve them using full table scan.

  IMPLEMENTATION
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    Run through all table indexes and find the shortest index that allows
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    records to be retrieved in given order. We look for the shortest index
    as we will have fewer index pages to read with it.
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    This function is used only by UPDATE/DELETE, so we take into account how
    the UPDATE/DELETE code will work:
     * index can only be scanned in forward direction
     * HA_EXTRA_KEYREAD will not be used
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    Perhaps these assumptions could be relaxed.
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  RETURN
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    Number of the index that produces the required ordering in the cheapest way
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    MAX_KEY if no such index was found.
*/

uint get_index_for_order(TABLE *table, ORDER *order, ha_rows limit)
{
  uint idx;
  uint match_key= MAX_KEY, match_key_len= MAX_KEY_LENGTH + 1;
  ORDER *ord;
  
  for (ord= order; ord; ord= ord->next)
    if (!ord->asc)
      return MAX_KEY;

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  for (idx= 0; idx < table->s->keys; idx++)
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  {
    if (!(table->keys_in_use_for_query.is_set(idx)))
      continue;
    KEY_PART_INFO *keyinfo= table->key_info[idx].key_part;
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    uint n_parts=  table->key_info[idx].key_parts;
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    uint partno= 0;
    
    /* 
      The below check is sufficient considering we now have either BTREE 
      indexes (records are returned in order for any index prefix) or HASH 
      indexes (records are not returned in order for any index prefix).
    */
    if (!(table->file->index_flags(idx, 0, 1) & HA_READ_ORDER))
      continue;
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    for (ord= order; ord && partno < n_parts; ord= ord->next, partno++)
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    {
      Item *item= order->item[0];
      if (!(item->type() == Item::FIELD_ITEM &&
           ((Item_field*)item)->field->eq(keyinfo[partno].field)))
        break;
    }
    
    if (!ord && table->key_info[idx].key_length < match_key_len)
    {
      /* 
        Ok, the ordering is compatible and this key is shorter then
        previous match (we want shorter keys as we'll have to read fewer
        index pages for the same number of records)
      */
      match_key= idx;
      match_key_len= table->key_info[idx].key_length;
    }
  }

  if (match_key != MAX_KEY)
  {
    /* 
      Found an index that allows records to be retrieved in the requested 
      order. Now we'll check if using the index is cheaper then doing a table
      scan.
    */
    double full_scan_time= table->file->scan_time();
    double index_scan_time= table->file->read_time(match_key, 1, limit);
    if (index_scan_time > full_scan_time)
      match_key= MAX_KEY;
  }
  return match_key;
}


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/*
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  Table rows retrieval plan. Range optimizer creates QUICK_SELECT_I-derived
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  objects from table read plans.
*/
class TABLE_READ_PLAN
{
public:
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  /*
    Plan read cost, with or without cost of full row retrieval, depending
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    on plan creation parameters.
  */
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  double read_cost;
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  ha_rows records; /* estimate of #rows to be examined */
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  /*
    If TRUE, the scan returns rows in rowid order. This is used only for
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    scans that can be both ROR and non-ROR.
  */
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  bool is_ror;
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  /*
    Create quick select for this plan.
    SYNOPSIS
     make_quick()
       param               Parameter from test_quick_select
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       retrieve_full_rows  If TRUE, created quick select will do full record
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                           retrieval.
       parent_alloc        Memory pool to use, if any.
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    NOTES
      retrieve_full_rows is ignored by some implementations.
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    RETURN
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      created quick select
      NULL on any error.
  */
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  virtual QUICK_SELECT_I *make_quick(PARAM *param,
                                     bool retrieve_full_rows,
                                     MEM_ROOT *parent_alloc=NULL) = 0;

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  /* Table read plans are allocated on MEM_ROOT and are never deleted */
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  static void *operator new(size_t size, MEM_ROOT *mem_root)
  { return (void*) alloc_root(mem_root, (uint) size); }
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  static void operator delete(void *ptr,size_t size) { TRASH(ptr, size); }
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  static void operator delete(void *ptr, MEM_ROOT *mem_root) { /* Never called */ }
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  virtual ~TABLE_READ_PLAN() {}               /* Remove gcc warning */

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};

class TRP_ROR_INTERSECT;
class TRP_ROR_UNION;
class TRP_INDEX_MERGE;


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/*
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  Plan for a QUICK_RANGE_SELECT scan.
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  TRP_RANGE::make_quick ignores retrieve_full_rows parameter because
  QUICK_RANGE_SELECT doesn't distinguish between 'index only' scans and full
  record retrieval scans.
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*/
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class TRP_RANGE : public TABLE_READ_PLAN
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{
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public:
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  SEL_ARG *key; /* set of intervals to be used in "range" method retrieval */
  uint     key_idx; /* key number in PARAM::key */
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  TRP_RANGE(SEL_ARG *key_arg, uint idx_arg)
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   : key(key_arg), key_idx(idx_arg)
  {}
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  virtual ~TRP_RANGE() {}                     /* Remove gcc warning */
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  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
                             MEM_ROOT *parent_alloc)
  {
    DBUG_ENTER("TRP_RANGE::make_quick");
    QUICK_RANGE_SELECT *quick;
    if ((quick= get_quick_select(param, key_idx, key, parent_alloc)))
    {
      quick->records= records;
      quick->read_time= read_cost;
    }
    DBUG_RETURN(quick);
  }
};
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/* Plan for QUICK_ROR_INTERSECT_SELECT scan. */

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class TRP_ROR_INTERSECT : public TABLE_READ_PLAN
{
public:
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  TRP_ROR_INTERSECT() {}                      /* Remove gcc warning */
  virtual ~TRP_ROR_INTERSECT() {}             /* Remove gcc warning */
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  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
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                             MEM_ROOT *parent_alloc);
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  /* Array of pointers to ROR range scans used in this intersection */
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  struct st_ror_scan_info **first_scan;
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  struct st_ror_scan_info **last_scan; /* End of the above array */
  struct st_ror_scan_info *cpk_scan;  /* Clustered PK scan, if there is one */
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  bool is_covering; /* TRUE if no row retrieval phase is necessary */
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  double index_scan_costs; /* SUM(cost(index_scan)) */
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};

2008

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/*
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  Plan for QUICK_ROR_UNION_SELECT scan.
  QUICK_ROR_UNION_SELECT always retrieves full rows, so retrieve_full_rows
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  is ignored by make_quick.
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*/
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class TRP_ROR_UNION : public TABLE_READ_PLAN
{
public:
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  TRP_ROR_UNION() {}                          /* Remove gcc warning */
  virtual ~TRP_ROR_UNION() {}                 /* Remove gcc warning */
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  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
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                             MEM_ROOT *parent_alloc);
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  TABLE_READ_PLAN **first_ror; /* array of ptrs to plans for merged scans */
  TABLE_READ_PLAN **last_ror;  /* end of the above array */
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};

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/*
  Plan for QUICK_INDEX_MERGE_SELECT scan.
  QUICK_ROR_INTERSECT_SELECT always retrieves full rows, so retrieve_full_rows
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  is ignored by make_quick.
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*/

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class TRP_INDEX_MERGE : public TABLE_READ_PLAN
{
public:
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  TRP_INDEX_MERGE() {}                        /* Remove gcc warning */
  virtual ~TRP_INDEX_MERGE() {}               /* Remove gcc warning */
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  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
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                             MEM_ROOT *parent_alloc);
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  TRP_RANGE **range_scans; /* array of ptrs to plans of merged scans */
  TRP_RANGE **range_scans_end; /* end of the array */
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};


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/*
  Plan for a QUICK_GROUP_MIN_MAX_SELECT scan. 
*/

class TRP_GROUP_MIN_MAX : public TABLE_READ_PLAN
{
private:
  bool have_min, have_max;
  KEY_PART_INFO *min_max_arg_part;
  uint group_prefix_len;
  uint used_key_parts;
  uint group_key_parts;
  KEY *index_info;
  uint index;
  uint key_infix_len;
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  uchar key_infix[MAX_KEY_LENGTH];
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  SEL_TREE *range_tree; /* Represents all range predicates in the query. */
  SEL_ARG  *index_tree; /* The SEL_ARG sub-tree corresponding to index_info. */
  uint param_idx; /* Index of used key in param->key. */
  /* Number of records selected by the ranges in index_tree. */
public:
  ha_rows quick_prefix_records;
public:
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  TRP_GROUP_MIN_MAX(bool have_min_arg, bool have_max_arg,
                    KEY_PART_INFO *min_max_arg_part_arg,
                    uint group_prefix_len_arg, uint used_key_parts_arg,
                    uint group_key_parts_arg, KEY *index_info_arg,
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                    uint index_arg, uint key_infix_len_arg,
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                    uchar *key_infix_arg,
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                    SEL_TREE *tree_arg, SEL_ARG *index_tree_arg,
                    uint param_idx_arg, ha_rows quick_prefix_records_arg)
  : have_min(have_min_arg), have_max(have_max_arg),
    min_max_arg_part(min_max_arg_part_arg),
    group_prefix_len(group_prefix_len_arg), used_key_parts(used_key_parts_arg),
    group_key_parts(group_key_parts_arg), index_info(index_info_arg),
    index(index_arg), key_infix_len(key_infix_len_arg), range_tree(tree_arg),
    index_tree(index_tree_arg), param_idx(param_idx_arg),
    quick_prefix_records(quick_prefix_records_arg)
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    {
      if (key_infix_len)
        memcpy(this->key_infix, key_infix_arg, key_infix_len);
    }
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  virtual ~TRP_GROUP_MIN_MAX() {}             /* Remove gcc warning */
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  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
                             MEM_ROOT *parent_alloc);
};


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/*
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  Fill param->needed_fields with bitmap of fields used in the query.
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  SYNOPSIS
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    fill_used_fields_bitmap()
      param Parameter from test_quick_select function.
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  NOTES
    Clustered PK members are not put into the bitmap as they are implicitly
    present in all keys (and it is impossible to avoid reading them).
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  RETURN
    0  Ok
    1  Out of memory.
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*/

static int fill_used_fields_bitmap(PARAM *param)
{
  TABLE *table= param->table;
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  my_bitmap_map *tmp;
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  uint pk;
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  param->tmp_covered_fields.bitmap= 0;
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  param->fields_bitmap_size= table->s->column_bitmap_size;
  if (!(tmp= (my_bitmap_map*) alloc_root(param->mem_root,
                                  param->fields_bitmap_size)) ||
      bitmap_init(&param->needed_fields, tmp, table->s->fields, FALSE))
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    return 1;
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  bitmap_copy(&param->needed_fields, table->read_set);
  bitmap_union(&param->needed_fields, table->write_set);
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  pk= param->table->s->primary_key;
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  if (pk != MAX_KEY && param->table->file->primary_key_is_clustered())
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  {
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    /* The table uses clustered PK and it is not internally generated */
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    KEY_PART_INFO *key_part= param->table->key_info[pk].key_part;
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    KEY_PART_INFO *key_part_end= key_part +
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                                 param->table->key_info[pk].key_parts;
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    for (;key_part != key_part_end; ++key_part)
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      bitmap_clear_bit(&param->needed_fields, key_part->fieldnr-1);
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  }
  return 0;
}


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/*
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  Test if a key can be used in different ranges
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  SYNOPSIS
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    SQL_SELECT::test_quick_select()
      thd               Current thread
      keys_to_use       Keys to use for range retrieval
      prev_tables       Tables assumed to be already read when the scan is
                        performed (but not read at the moment of this call)
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      limit             Query limit
      force_quick_range Prefer to use range (instead of full table scan) even
                        if it is more expensive.
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  NOTES
    Updates the following in the select parameter:
      needed_reg - Bits for keys with may be used if all prev regs are read
      quick      - Parameter to use when reading records.
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    In the table struct the following information is updated:
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      quick_keys           - Which keys can be used
      quick_rows           - How many rows the key matches
      quick_condition_rows - E(# rows that will satisfy the table condition)

  IMPLEMENTATION
    quick_condition_rows value is obtained as follows:
      
      It is a minimum of E(#output rows) for all considered table access
      methods (range and index_merge accesses over various indexes).
    
    The obtained value is not a true E(#rows that satisfy table condition)
    but rather a pessimistic estimate. To obtain a true E(#...) one would
    need to combine estimates of various access methods, taking into account
    correlations between sets of rows they will return.
    
    For example, if values of tbl.key1 and tbl.key2 are independent (a right
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    assumption if we have no information about their correlation) then the
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    correct estimate will be:
    
      E(#rows("tbl.key1 < c1 AND tbl.key2 < c2")) = 
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      = E(#rows(tbl.key1 < c1)) / total_rows(tbl) * E(#rows(tbl.key2 < c2)
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    which is smaller than 
      
       MIN(E(#rows(tbl.key1 < c1), E(#rows(tbl.key2 < c2)))

    which is currently produced.
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  TODO
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   * Change the value returned in quick_condition_rows from a pessimistic
     estimate to true E(#rows that satisfy table condition). 
     (we can re-use some of E(#rows) calcuation code from index_merge/intersection 
      for this)
   
   * Check if this function really needs to modify keys_to_use, and change the
     code to pass it by reference if it doesn't.
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   * In addition to force_quick_range other means can be (an usually are) used
     to make this function prefer range over full table scan. Figure out if
     force_quick_range is really needed.
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  RETURN
   -1 if impossible select (i.e. certainly no rows will be selected)
    0 if can't use quick_select
    1 if found usable ranges and quick select has been successfully created.
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*/
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int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
				  table_map prev_tables,
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				  ha_rows limit, bool force_quick_range)
{
  uint idx;
  double scan_time;
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  DBUG_ENTER("SQL_SELECT::test_quick_select");
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  DBUG_PRINT("enter",("keys_to_use: %lu  prev_tables: %lu  const_tables: %lu",
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		      (ulong) keys_to_use.to_ulonglong(), (ulong) prev_tables,
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		      (ulong) const_tables));
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  DBUG_PRINT("info", ("records: %lu", (ulong) head->file->stats.records));
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  delete quick;
  quick=0;
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  needed_reg.clear_all();
  quick_keys.clear_all();
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  if (keys_to_use.is_clear_all())
    DBUG_RETURN(0);
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  records= head->file->stats.records;
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  if (!records)
    records++;					/* purecov: inspected */
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  scan_time= (double) records / TIME_FOR_COMPARE + 1;
  read_time= (double) head->file->scan_time() + scan_time + 1.1;
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  if (head->force_index)
    scan_time= read_time= DBL_MAX;
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  if (limit < records)
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    read_time= (double) records + scan_time + 1; // Force to use index
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  else if (read_time <= 2.0 && !force_quick_range)
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    DBUG_RETURN(0);				/* No need for quick select */
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  DBUG_PRINT("info",("Time to scan table: %g", read_time));
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  keys_to_use.intersect(head->keys_in_use_for_query);
  if (!keys_to_use.is_clear_all())
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  {
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#ifndef EMBEDDED_LIBRARY                      // Avoid compiler warning
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    uchar buff[STACK_BUFF_ALLOC];
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#endif
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    MEM_ROOT alloc;
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    SEL_TREE *tree= NULL;
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    KEY_PART *key_parts;
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    KEY *key_info;
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    PARAM param;
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    if (check_stack_overrun(thd, 2*STACK_MIN_SIZE, buff))
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      DBUG_RETURN(0);                           // Fatal error flag is set

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    /* set up parameter that is passed to all functions */
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    param.thd= thd;
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    param.baseflag= head->file->ha_table_flags();
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    param.prev_tables=prev_tables | const_tables;
    param.read_tables=read_tables;
    param.current_table= head->map;
    param.table=head;
    param.keys=0;
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    param.mem_root= &alloc;
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    param.old_root= thd->mem_root;
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    param.needed_reg= &needed_reg;
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    param.imerge_cost_buff_size= 0;
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    param.using_real_indexes= TRUE;
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    param.remove_jump_scans= TRUE;
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    thd->no_errors=1;				// Don't warn about NULL
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    init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
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    if (!(param.key_parts= (KEY_PART*) alloc_root(&alloc,
                                                  sizeof(KEY_PART)*
                                                  head->s->key_parts)) ||
        fill_used_fields_bitmap(&param))
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    {
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      thd->no_errors=0;
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      free_root(&alloc,MYF(0));			// Return memory & allocator
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      DBUG_RETURN(0);				// Can't use range
    }
    key_parts= param.key_parts;
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    thd->mem_root= &alloc;
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    /*
      Make an array with description of all key parts of all table keys.
      This is used in get_mm_parts function.
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    */
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    key_info= head->key_info;
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    for (idx=0 ; idx < head->s->keys ; idx++, key_info++)
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    {
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      KEY_PART_INFO *key_part_info;
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      if (!keys_to_use.is_set(idx))
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	continue;
      if (key_info->flags & HA_FULLTEXT)
	continue;    // ToDo: ft-keys in non-ft ranges, if possible   SerG

      param.key[param.keys]=key_parts;
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      key_part_info= key_info->key_part;
      for (uint part=0 ; part < key_info->key_parts ;
	   part++, key_parts++, key_part_info++)
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      {
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	key_parts->key=		 param.keys;
	key_parts->part=	 part;
	key_parts->length=       key_part_info->length;
	key_parts->store_length= key_part_info->store_length;
	key_parts->field=	 key_part_info->field;
	key_parts->null_bit=	 key_part_info->null_bit;
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        key_parts->image_type =
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          (key_info->flags & HA_SPATIAL) ? Field::itMBR : Field::itRAW;
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        /* Only HA_PART_KEY_SEG is used */
        key_parts->flag=         (uint8) key_part_info->key_part_flag;
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      }
      param.real_keynr[param.keys++]=idx;
    }
    param.key_parts_end=key_parts;
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    param.alloced_sel_args= 0;
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    /* Calculate cost of full index read for the shortest covering index */
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    if (!head->covering_keys.is_clear_all())
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    {
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      int key_for_use= find_shortest_key(head, &head->covering_keys);
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      double key_read_time= (get_index_only_read_time(&param, records,
                                                     key_for_use) +
                             (double) records / TIME_FOR_COMPARE);
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      DBUG_PRINT("info",  ("'all'+'using index' scan will be using key %d, "
                           "read time %g", key_for_use, key_read_time));
      if (key_read_time < read_time)
        read_time= key_read_time;
    }
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    TABLE_READ_PLAN *best_trp= NULL;
    TRP_GROUP_MIN_MAX *group_trp;
    double best_read_time= read_time;

    if (cond)
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    {
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      if ((tree= get_mm_tree(&param,cond)))
      {
        if (tree->type == SEL_TREE::IMPOSSIBLE)
        {
          records=0L;                      /* Return -1 from this function. */
          read_time= (double) HA_POS_ERROR;
          goto free_mem;
        }
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        /*
          If the tree can't be used for range scans, proceed anyway, as we
          can construct a group-min-max quick select
        */
        if (tree->type != SEL_TREE::KEY && tree->type != SEL_TREE::KEY_SMALLER)
          tree= NULL;
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      }
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    }

    /*
      Try to construct a QUICK_GROUP_MIN_MAX_SELECT.
      Notice that it can be constructed no matter if there is a range tree.
    */
    group_trp= get_best_group_min_max(&param, tree);
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    if (group_trp)
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    {
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      param.table->quick_condition_rows= min(group_trp->records,
                                             head->file->stats.records);
      if (group_trp->read_cost < best_read_time)
      {
        best_trp= group_trp;
        best_read_time= best_trp->read_cost;
      }
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    }

    if (tree)
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    {
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      /*
        It is possible to use a range-based quick select (but it might be
        slower than 'all' table scan).
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      */
      if (tree->merges.is_empty())
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      {
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        TRP_RANGE         *range_trp;
        TRP_ROR_INTERSECT *rori_trp;
        bool can_build_covering= FALSE;

        /* Get best 'range' plan and prepare data for making other plans */
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        if ((range_trp= get_key_scans_params(&param, tree, FALSE, TRUE,
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                                             best_read_time)))
        {
          best_trp= range_trp;
          best_read_time= best_trp->read_cost;
        }

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        /*
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          Simultaneous key scans and row deletes on several handler
          objects are not allowed so don't use ROR-intersection for
          table deletes.
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        */
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        if ((thd->lex->sql_command != SQLCOM_DELETE) && 
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             optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE))
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        {
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          /*
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            Get best non-covering ROR-intersection plan and prepare data for
            building covering ROR-intersection.
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          */
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          if ((rori_trp= get_best_ror_intersect(&param, tree, best_read_time,
                                                &can_build_covering)))
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          {
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            best_trp= rori_trp;
            best_read_time= best_trp->read_cost;
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            /*
              Try constructing covering ROR-intersect only if it looks possible
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              and worth doing.
            */
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            if (!rori_trp->is_covering && can_build_covering &&
                (rori_trp= get_best_covering_ror_intersect(&param, tree,
                                                           best_read_time)))
              best_trp= rori_trp;
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          }
        }
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      }
      else
      {
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        if (optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE))
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        {
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          /* Try creating index_merge/ROR-union scan. */
          SEL_IMERGE *imerge;
          TABLE_READ_PLAN *best_conj_trp= NULL, *new_conj_trp;
          LINT_INIT(new_conj_trp); /* no empty index_merge lists possible */
          DBUG_PRINT("info",("No range reads possible,"
                             " trying to construct index_merge"));
          List_iterator_fast<SEL_IMERGE> it(tree->merges);
          while ((imerge= it++))
          {
            new_conj_trp= get_best_disjunct_quick(&param, imerge, best_read_time);
            if (new_conj_trp)
              set_if_smaller(param.table->quick_condition_rows, 
                             new_conj_trp->records);
            if (!best_conj_trp || (new_conj_trp && new_conj_trp->read_cost <
                                   best_conj_trp->read_cost))
              best_conj_trp= new_conj_trp;
          }
          if (best_conj_trp)
            best_trp= best_conj_trp;
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        }
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      }
    }
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    thd->mem_root= param.old_root;
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    /* If we got a read plan, create a quick select from it. */
    if (best_trp)
    {
      records= best_trp->records;
      if (!(quick= best_trp->make_quick(&param, TRUE)) || quick->init())
      {
        delete quick;
        quick= NULL;
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      }
    }
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  free_mem:
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    free_root(&alloc,MYF(0));			// Return memory & allocator
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    thd->mem_root= param.old_root;
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    thd->no_errors=0;
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  }
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  DBUG_EXECUTE("info", print_quick(quick, &needed_reg););
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  /*
    Assume that if the user is using 'limit' we will only need to scan
    limit rows if we are using a key
  */
  DBUG_RETURN(records ? test(quick) : -1);
}

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/****************************************************************************
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 * Partition pruning module
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 ****************************************************************************/
#ifdef WITH_PARTITION_STORAGE_ENGINE

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/*
  PartitionPruningModule

  This part of the code does partition pruning. Partition pruning solves the
  following problem: given a query over partitioned tables, find partitions
  that we will not need to access (i.e. partitions that we can assume to be
  empty) when executing the query.
  The set of partitions to prune doesn't depend on which query execution
  plan will be used to execute the query.
  
  HOW IT WORKS
  
  Partition pruning module makes use of RangeAnalysisModule. The following
  examples show how the problem of partition pruning can be reduced to the 
  range analysis problem:
  
  EXAMPLE 1
    Consider a query:
    
      SELECT * FROM t1 WHERE (t1.a < 5 OR t1.a = 10) AND t1.a > 3 AND t1.b='z'
    
    where table t1 is partitioned using PARTITION BY RANGE(t1.a).  An apparent
    way to find the used (i.e. not pruned away) partitions is as follows:
    
    1. analyze the WHERE clause and extract the list of intervals over t1.a
       for the above query we will get this list: {(3 < t1.a < 5), (t1.a=10)}

    2. for each interval I
       {
         find partitions that have non-empty intersection with I;
         mark them as used;
       }
       
  EXAMPLE 2
    Suppose the table is partitioned by HASH(part_func(t1.a, t1.b)). Then
    we need to:

    1. Analyze the WHERE clause and get a list of intervals over (t1.a, t1.b).
       The list of intervals we'll obtain will look like this:
       ((t1.a, t1.b) = (1,'foo')),
       ((t1.a, t1.b) = (2,'bar')), 
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       ((t1,a, t1.b) > (10,'zz'))
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    2. for each interval I 
       {
         if (the interval has form "(t1.a, t1.b) = (const1, const2)" )
         {
           calculate HASH(part_func(t1.a, t1.b));
           find which partition has records with this hash value and mark
             it as used;
         }
         else
         {
           mark all partitions as used; 
           break;
         }
       }

   For both examples the step #1 is exactly what RangeAnalysisModule could
   be used to do, if it was provided with appropriate index description
   (array of KEY_PART structures). 
   In example #1, we need to provide it with description of index(t1.a), 
   in example #2, we need to provide it with description of index(t1.a, t1.b).
   
   These index descriptions are further called "partitioning index
   descriptions". Note that it doesn't matter if such indexes really exist,
   as range analysis module only uses the description.
   
   Putting it all together, partitioning module works as follows:
   
   prune_partitions() {
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     call create_partition_index_description();
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     call get_mm_tree(); // invoke the RangeAnalysisModule
     
     // analyze the obtained interval list and get used partitions 
     call find_used_partitions();
  }

*/

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struct st_part_prune_param;
struct st_part_opt_info;

typedef void (*mark_full_part_func)(partition_info*, uint32);

/*
  Partition pruning operation context
*/
typedef struct st_part_prune_param
{
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  RANGE_OPT_PARAM range_param; /* Range analyzer parameters */
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  /***************************************************************
   Following fields are filled in based solely on partitioning 
   definition and not modified after that:
   **************************************************************/
  partition_info *part_info; /* Copy of table->part_info */
  /* Function to get partition id from partitioning fields only */
  get_part_id_func get_top_partition_id_func;
  /* Function to mark a partition as used (w/all subpartitions if they exist)*/
  mark_full_part_func mark_full_partition_used;
 
  /* Partitioning 'index' description, array of key parts */
  KEY_PART *key;
  
  /*
    Number of fields in partitioning 'index' definition created for
    partitioning (0 if partitioning 'index' doesn't include partitioning
    fields)
  */
  uint part_fields;
  uint subpart_fields; /* Same as above for subpartitioning */
  
  /* 
    Number of the last partitioning field keypart in the index, or -1 if
    partitioning index definition doesn't include partitioning fields.
  */
  int last_part_partno;
  int last_subpart_partno; /* Same as above for supartitioning */

  /*
    is_part_keypart[i] == test(keypart #i in partitioning index is a member
                               used in partitioning)
    Used to maintain current values of cur_part_fields and cur_subpart_fields
  */
  my_bool *is_part_keypart;
  /* Same as above for subpartitioning */
  my_bool *is_subpart_keypart;

  /***************************************************************
   Following fields form find_used_partitions() recursion context:
   **************************************************************/
  SEL_ARG **arg_stack;     /* "Stack" of SEL_ARGs */
  SEL_ARG **arg_stack_end; /* Top of the stack    */
  /* Number of partitioning fields for which we have a SEL_ARG* in arg_stack */
  uint cur_part_fields;
  /* Same as cur_part_fields, but for subpartitioning */
  uint cur_subpart_fields;
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  /* Iterator to be used to obtain the "current" set of used partitions */
  PARTITION_ITERATOR part_iter;

  /* Initialized bitmap of no_subparts size */
  MY_BITMAP subparts_bitmap;
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} PART_PRUNE_PARAM;

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static bool create_partition_index_description(PART_PRUNE_PARAM *prune_par);
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static int find_used_partitions(PART_PRUNE_PARAM *ppar, SEL_ARG *key_tree);
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static int find_used_partitions_imerge(PART_PRUNE_PARAM *ppar,
                                       SEL_IMERGE *imerge);
static int find_used_partitions_imerge_list(PART_PRUNE_PARAM *ppar,
                                            List<SEL_IMERGE> &merges);
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static void mark_all_partitions_as_used(partition_info *part_info);

#ifndef DBUG_OFF
static void print_partitioning_index(KEY_PART *parts, KEY_PART *parts_end);
static void dbug_print_field(Field *field);
static void dbug_print_segment_range(SEL_ARG *arg, KEY_PART *part);
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static void dbug_print_singlepoint_range(SEL_ARG **start, uint num);
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#endif


/*
  Perform partition pruning for a given table and condition.

  SYNOPSIS
    prune_partitions()
      thd           Thread handle
      table         Table to perform partition pruning for
      pprune_cond   Condition to use for partition pruning
  
  DESCRIPTION
    This function assumes that all partitions are marked as unused when it
    is invoked. The function analyzes the condition, finds partitions that
    need to be used to retrieve the records that match the condition, and 
    marks them as used by setting appropriate bit in part_info->used_partitions
    In the worst case all partitions are marked as used.

  NOTE
    This function returns promptly if called for non-partitioned table.

  RETURN
    TRUE   We've inferred that no partitions need to be used (i.e. no table
           records will satisfy pprune_cond)
    FALSE  Otherwise
*/

bool prune_partitions(THD *thd, TABLE *table, Item *pprune_cond)
{
  bool retval= FALSE;
  partition_info *part_info = table->part_info;
  DBUG_ENTER("prune_partitions");

  if (!part_info)
    DBUG_RETURN(FALSE); /* not a partitioned table */
  
  if (!pprune_cond)
  {
    mark_all_partitions_as_used(part_info);
    DBUG_RETURN(FALSE);
  }
  
  PART_PRUNE_PARAM prune_param;
  MEM_ROOT alloc;
  RANGE_OPT_PARAM  *range_par= &prune_param.range_param;
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  my_bitmap_map *old_sets[2];
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  prune_param.part_info= part_info;
  init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
  range_par->mem_root= &alloc;
  range_par->old_root= thd->mem_root;

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  if (create_partition_index_description(&prune_param))
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  {
    mark_all_partitions_as_used(part_info);
    free_root(&alloc,MYF(0));		// Return memory & allocator
    DBUG_RETURN(FALSE);
  }
  
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  dbug_tmp_use_all_columns(table, old_sets, 
                           table->read_set, table->write_set);
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  range_par->thd= thd;
  range_par->table= table;
  /* range_par->cond doesn't need initialization */
  range_par->prev_tables= range_par->read_tables= 0;
  range_par->current_table= table->map;

  range_par->keys= 1; // one index
  range_par->using_real_indexes= FALSE;
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  range_par->remove_jump_scans= FALSE;
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  range_par->real_keynr[0]= 0;
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  range_par->alloced_sel_args= 0;
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  thd->no_errors=1;				// Don't warn about NULL
  thd->mem_root=&alloc;
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  bitmap_clear_all(&part_info->used_partitions);

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  prune_param.key= prune_param.range_param.key_parts;
  SEL_TREE *tree;
  int res;

  tree= get_mm_tree(range_par, pprune_cond);
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  if (!tree)
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    goto all_used;

  if (tree->type == SEL_TREE::IMPOSSIBLE)
  {
    retval= TRUE;
    goto end;
  }
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  if (tree->type != SEL_TREE::KEY && tree->type != SEL_TREE::KEY_SMALLER)
    goto all_used;
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  if (tree->merges.is_empty())
  {
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    /* Range analysis has produced a single list of intervals. */
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    prune_param.arg_stack_end= prune_param.arg_stack;
    prune_param.cur_part_fields= 0;
    prune_param.cur_subpart_fields= 0;
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    init_all_partitions_iterator(part_info, &prune_param.part_iter);
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    if (!tree->keys[0] || (-1 == (res= find_used_partitions(&prune_param,
                                                            tree->keys[0]))))
      goto all_used;
  }
  else
  {
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    if (tree->merges.elements == 1)
    {
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      /* 
        Range analysis has produced a "merge" of several intervals lists, a 
        SEL_TREE that represents an expression in form         
          sel_imerge = (tree1 OR tree2 OR ... OR treeN)
        that cannot be reduced to one tree. This can only happen when 
        partitioning index has several keyparts and the condition is OR of
        conditions that refer to different key parts. For example, we'll get
        here for "partitioning_field=const1 OR subpartitioning_field=const2"
      */
      if (-1 == (res= find_used_partitions_imerge(&prune_param,
                                                  tree->merges.head())))
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        goto all_used;
    }
    else
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    {
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      /* 
        Range analysis has produced a list of several imerges, i.e. a
        structure that represents a condition in form 
        imerge_list= (sel_imerge1 AND sel_imerge2 AND ... AND sel_imergeN)
        This is produced for complicated WHERE clauses that range analyzer
        can't really analyze properly.
      */
      if (-1 == (res= find_used_partitions_imerge_list(&prune_param,
                                                       tree->merges)))
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        goto all_used;
    }
  }
  
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  /*
    res == 0 => no used partitions => retval=TRUE
    res == 1 => some used partitions => retval=FALSE
    res == -1 - we jump over this line to all_used:
  */
  retval= test(!res);
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  goto end;

all_used:
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  retval= FALSE; // some partitions are used
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  mark_all_partitions_as_used(prune_param.part_info);
end:
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  dbug_tmp_restore_column_maps(table->read_set, table->write_set, old_sets);
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  thd->no_errors=0;
  thd->mem_root= range_par->old_root;
  free_root(&alloc,MYF(0));			// Return memory & allocator
  DBUG_RETURN(retval);
}


/*
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  Store field key image to table record
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  SYNOPSIS
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    store_key_image_to_rec()
      field  Field which key image should be stored
      ptr    Field value in key format
      len    Length of the value, in bytes

  DESCRIPTION
    Copy the field value from its key image to the table record. The source
    is the value in key image format, occupying len bytes in buffer pointed
    by ptr. The destination is table record, in "field value in table record"
    format.
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*/

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void store_key_image_to_rec(Field *field, uchar *ptr, uint len)
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{
  /* Do the same as print_key() does */ 
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  my_bitmap_map *old_map;

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  if (field->real_maybe_null())
  {
    if (*ptr)
    {
      field->set_null();
      return;
    }
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    field->set_notnull();
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    ptr++;
  }    
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  old_map= dbug_tmp_use_all_columns(field->table,
                                    field->table->write_set);
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  field->set_key_image(ptr, len); 
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  dbug_tmp_restore_column_map(field->table->write_set, old_map);
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}


/*
  For SEL_ARG* array, store sel_arg->min values into table record buffer

  SYNOPSIS
    store_selargs_to_rec()
      ppar   Partition pruning context
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      start  Array of SEL_ARG* for which the minimum values should be stored
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      num    Number of elements in the array
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  DESCRIPTION
    For each SEL_ARG* interval in the specified array, store the left edge
    field value (sel_arg->min, key image format) into the table record.
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*/

static void store_selargs_to_rec(PART_PRUNE_PARAM *ppar, SEL_ARG **start,
                                 int num)
{
  KEY_PART *parts= ppar->range_param.key_parts;
  for (SEL_ARG **end= start + num; start != end; start++)
  {
    SEL_ARG *sel_arg= (*start);
    store_key_image_to_rec(sel_arg->field, sel_arg->min_value,
                           parts[sel_arg->part].length);
  }
}


/* Mark a partition as used in the case when there are no subpartitions */
static void mark_full_partition_used_no_parts(partition_info* part_info,
                                              uint32 part_id)
{
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  DBUG_ENTER("mark_full_partition_used_no_parts");
  DBUG_PRINT("enter", ("Mark partition %u as used", part_id));
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  bitmap_set_bit(&part_info->used_partitions, part_id);
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  DBUG_VOID_RETURN;
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}


/* Mark a partition as used in the case when there are subpartitions */
static void mark_full_partition_used_with_parts(partition_info *part_info,
                                                uint32 part_id)
{
  uint32 start= part_id * part_info->no_subparts;
  uint32 end=   start + part_info->no_subparts; 
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  DBUG_ENTER("mark_full_partition_used_with_parts");

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  for (; start != end; start++)
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  {
    DBUG_PRINT("info", ("1:Mark subpartition %u as used", start));
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    bitmap_set_bit(&part_info->used_partitions, start);
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  }
  DBUG_VOID_RETURN;
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}

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/*
  Find the set of used partitions for List<SEL_IMERGE>
  SYNOPSIS
    find_used_partitions_imerge_list
      ppar      Partition pruning context.
      key_tree  Intervals tree to perform pruning for.
      
  DESCRIPTION
    List<SEL_IMERGE> represents "imerge1 AND imerge2 AND ...". 
    The set of used partitions is an intersection of used partitions sets
    for imerge_{i}.
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    We accumulate this intersection in a separate bitmap.
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  RETURN 
    See find_used_partitions()
*/

static int find_used_partitions_imerge_list(PART_PRUNE_PARAM *ppar,
                                            List<SEL_IMERGE> &merges)
{
  MY_BITMAP all_merges;
  uint bitmap_bytes;
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  my_bitmap_map *bitmap_buf;
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  uint n_bits= ppar->part_info->used_partitions.n_bits;
  bitmap_bytes= bitmap_buffer_size(n_bits);
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  if (!(bitmap_buf= (my_bitmap_map*) alloc_root(ppar->range_param.mem_root,
                                                bitmap_bytes)))
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  {
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    /*
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      Fallback, process just the first SEL_IMERGE. This can leave us with more
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      partitions marked as used then actually needed.
    */
    return find_used_partitions_imerge(ppar, merges.head());
  }
  bitmap_init(&all_merges, bitmap_buf, n_bits, FALSE);
  bitmap_set_prefix(&all_merges, n_bits);
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  List_iterator<SEL_IMERGE> it(merges);
  SEL_IMERGE *imerge;
  while ((imerge=it++))
  {
    int res= find_used_partitions_imerge(ppar, imerge);
    if (!res)
    {
      /* no used partitions on one ANDed imerge => no used partitions at all */
      return 0;
    }
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    if (res != -1)
      bitmap_intersect(&all_merges, &ppar->part_info->used_partitions);

    if (bitmap_is_clear_all(&all_merges))
      return 0;

    bitmap_clear_all(&ppar->part_info->used_partitions);
  }
  memcpy(ppar->part_info->used_partitions.bitmap, all_merges.bitmap,
         bitmap_bytes);
  return 1;
}


/*
  Find the set of used partitions for SEL_IMERGE structure
  SYNOPSIS
    find_used_partitions_imerge()
      ppar      Partition pruning context.
      key_tree  Intervals tree to perform pruning for.
      
  DESCRIPTION
    SEL_IMERGE represents "tree1 OR tree2 OR ...". The implementation is
    trivial - just use mark used partitions for each tree and bail out early
    if for some tree_{i} all partitions are used.
 
  RETURN 
    See find_used_partitions().
*/

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static
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int find_used_partitions_imerge(PART_PRUNE_PARAM *ppar, SEL_IMERGE *imerge)
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{
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  int res= 0;
  for (SEL_TREE **ptree= imerge->trees; ptree < imerge->trees_next; ptree++)
  {
    ppar->arg_stack_end= ppar->arg_stack;
    ppar->cur_part_fields= 0;
    ppar->cur_subpart_fields= 0;
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    init_all_partitions_iterator(ppar->part_info, &ppar->part_iter);
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    SEL_ARG *key_tree= (*ptree)->keys[0];
    if (!key_tree || (-1 == (res |= find_used_partitions(ppar, key_tree))))
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      return -1;
  }
  return res;
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}


/*
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  Collect partitioning ranges for the SEL_ARG tree and mark partitions as used
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  SYNOPSIS
    find_used_partitions()
      ppar      Partition pruning context.
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      key_tree  SEL_ARG range tree to perform pruning for
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  DESCRIPTION
    This function 
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      * recursively walks the SEL_ARG* tree collecting partitioning "intervals"
      * finds the partitions one needs to use to get rows in these intervals
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      * marks these partitions as used.
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    The next session desribes the process in greater detail.
 
  IMPLEMENTATION
    TYPES OF RESTRICTIONS THAT WE CAN OBTAIN PARTITIONS FOR    
    We can find out which [sub]partitions to use if we obtain restrictions on 
    [sub]partitioning fields in the following form:
    1.  "partition_field1=const1 AND ... AND partition_fieldN=constN"
    1.1  Same as (1) but for subpartition fields

    If partitioning supports interval analysis (i.e. partitioning is a
    function of a single table field, and partition_info::
    get_part_iter_for_interval != NULL), then we can also use condition in
    this form:
    2.  "const1 <=? partition_field <=? const2"
    2.1  Same as (2) but for subpartition_field

    INFERRING THE RESTRICTIONS FROM SEL_ARG TREE
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    The below is an example of what SEL_ARG tree may represent:
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    (start)
     |                           $
     |   Partitioning keyparts   $  subpartitioning keyparts
     |                           $
     |     ...          ...      $
     |      |            |       $
     | +---------+  +---------+  $  +-----------+  +-----------+
     \-| par1=c1 |--| par2=c2 |-----| subpar1=c3|--| subpar2=c5|
       +---------+  +---------+  $  +-----------+  +-----------+
            |                    $        |             |
            |                    $        |        +-----------+ 
            |                    $        |        | subpar2=c6|
            |                    $        |        +-----------+ 
            |                    $        |
            |                    $  +-----------+  +-----------+
            |                    $  | subpar1=c4|--| subpar2=c8|
            |                    $  +-----------+  +-----------+
            |                    $         
            |                    $
       +---------+               $  +------------+  +------------+
       | par1=c2 |------------------| subpar1=c10|--| subpar2=c12|
       +---------+               $  +------------+  +------------+
            |                    $
           ...                   $

    The up-down connections are connections via SEL_ARG::left and
    SEL_ARG::right. A horizontal connection to the right is the
    SEL_ARG::next_key_part connection.
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    find_used_partitions() traverses the entire tree via recursion on
     * SEL_ARG::next_key_part (from left to right on the picture)
     * SEL_ARG::left|right (up/down on the pic). Left-right recursion is
       performed for each depth level.
    
    Recursion descent on SEL_ARG::next_key_part is used to accumulate (in
    ppar->arg_stack) constraints on partitioning and subpartitioning fields.
    For the example in the above picture, one of stack states is:
      in find_used_partitions(key_tree = "subpar2=c5") (***)
      in find_used_partitions(key_tree = "subpar1=c3")
      in find_used_partitions(key_tree = "par2=c2")   (**)
      in find_used_partitions(key_tree = "par1=c1")
      in prune_partitions(...)
    We apply partitioning limits as soon as possible, e.g. when we reach the
    depth (**), we find which partition(s) correspond to "par1=c1 AND par2=c2",
    and save them in ppar->part_iter.
    When we reach the depth (***), we find which subpartition(s) correspond to
    "subpar1=c3 AND subpar2=c5", and then mark appropriate subpartitions in
    appropriate subpartitions as used.
    
    It is possible that constraints on some partitioning fields are missing.
    For the above example, consider this stack state:
      in find_used_partitions(key_tree = "subpar2=c12") (***)
      in find_used_partitions(key_tree = "subpar1=c10")
      in find_used_partitions(key_tree = "par1=c2")
      in prune_partitions(...)
    Here we don't have constraints for all partitioning fields. Since we've
    never set the ppar->part_iter to contain used set of partitions, we use
    its default "all partitions" value.  We get  subpartition id for 
    "subpar1=c3 AND subpar2=c5", and mark that subpartition as used in every
    partition.

    The inverse is also possible: we may get constraints on partitioning
    fields, but not constraints on subpartitioning fields. In that case,
    calls to find_used_partitions() with depth below (**) will return -1,
    and we will mark entire partition as used.
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  TODO
    Replace recursion on SEL_ARG::left and SEL_ARG::right with a loop
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  RETURN
    1   OK, one or more [sub]partitions are marked as used.
    0   The passed condition doesn't match any partitions
   -1   Couldn't infer any partition pruning "intervals" from the passed 
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        SEL_ARG* tree (which means that all partitions should be marked as
        used) Marking partitions as used is the responsibility of the caller.
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*/

static 
int find_used_partitions(PART_PRUNE_PARAM *ppar, SEL_ARG *key_tree)
{
  int res, left_res=0, right_res=0;
  int partno= (int)key_tree->part;
  bool pushed= FALSE;
  bool set_full_part_if_bad_ret= FALSE;

  if (key_tree->left != &null_element)
  {
    if (-1 == (left_res= find_used_partitions(ppar,key_tree->left)))
      return -1;
  }

  if (key_tree->type == SEL_ARG::KEY_RANGE)
  {
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    if (partno == 0 && (NULL != ppar->part_info->get_part_iter_for_interval))
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    {
      /* 
        Partitioning is done by RANGE|INTERVAL(monotonic_expr(fieldX)), and
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        we got "const1 CMP fieldX CMP const2" interval <-- psergey-todo: change
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      */
      DBUG_EXECUTE("info", dbug_print_segment_range(key_tree,
                                                    ppar->range_param.
                                                    key_parts););
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      res= ppar->part_info->
           get_part_iter_for_interval(ppar->part_info,
                                      FALSE,
                                      key_tree->min_value, 
                                      key_tree->max_value,
                                      key_tree->min_flag | key_tree->max_flag,
                                      &ppar->part_iter);
      if (!res)
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        goto go_right; /* res==0 --> no satisfying partitions */
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      if (res == -1)
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      {
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        //get a full range iterator
        init_all_partitions_iterator(ppar->part_info, &ppar->part_iter);
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      }
      /* 
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        Save our intent to mark full partition as used if we will not be able
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        to obtain further limits on subpartitions
      */
      set_full_part_if_bad_ret= TRUE;
      goto process_next_key_part;
    }

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    if (partno == ppar->last_subpart_partno && 
        (NULL != ppar->part_info->get_subpart_iter_for_interval))
    {
      PARTITION_ITERATOR subpart_iter;
      DBUG_EXECUTE("info", dbug_print_segment_range(key_tree,
                                                    ppar->range_param.
                                                    key_parts););
      res= ppar->part_info->
           get_subpart_iter_for_interval(ppar->part_info,
                                         TRUE,
                                         key_tree->min_value, 
                                         key_tree->max_value,
                                         key_tree->min_flag | key_tree->max_flag,
                                         &subpart_iter);
      DBUG_ASSERT(res); /* We can't get "no satisfying subpartitions" */
      if (res == -1)
        return -1; /* all subpartitions satisfy */
        
      uint32 subpart_id;
      bitmap_clear_all(&ppar->subparts_bitmap);
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      while ((subpart_id= subpart_iter.get_next(&subpart_iter)) !=
             NOT_A_PARTITION_ID)
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        bitmap_set_bit(&ppar->subparts_bitmap, subpart_id);

      /* Mark each partition as used in each subpartition.  */
      uint32 part_id;
      while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) !=
              NOT_A_PARTITION_ID)
      {
        for (uint i= 0; i < ppar->part_info->no_subparts; i++)
          if (bitmap_is_set(&ppar->subparts_bitmap, i))
            bitmap_set_bit(&ppar->part_info->used_partitions,
                           part_id * ppar->part_info->no_subparts + i);
      }
      goto go_right;
    }

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    if (key_tree->is_singlepoint())
    {
      pushed= TRUE;
      ppar->cur_part_fields+=    ppar->is_part_keypart[partno];
      ppar->cur_subpart_fields+= ppar->is_subpart_keypart[partno];
      *(ppar->arg_stack_end++) = key_tree;

      if (partno == ppar->last_part_partno &&
          ppar->cur_part_fields == ppar->part_fields)
      {
        /* 
          Ok, we've got "fieldN<=>constN"-type SEL_ARGs for all partitioning
          fields. Save all constN constants into table record buffer.
        */
        store_selargs_to_rec(ppar, ppar->arg_stack, ppar->part_fields);
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        DBUG_EXECUTE("info", dbug_print_singlepoint_range(ppar->arg_stack,
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                                                       ppar->part_fields););
        uint32 part_id;
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        longlong func_value;
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        /* Find in which partition the {const1, ...,constN} tuple goes */
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        if (ppar->get_top_partition_id_func(ppar->part_info, &part_id,
                                            &func_value))
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        {
          res= 0; /* No satisfying partitions */
          goto pop_and_go_right;
        }
        /* Rembember the limit we got - single partition #part_id */
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        init_single_partition_iterator(part_id, &ppar->part_iter);
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        /*
          If there are no subpartitions/we fail to get any limit for them, 
          then we'll mark full partition as used. 
        */
        set_full_part_if_bad_ret= TRUE;
        goto process_next_key_part;
      }

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      if (partno == ppar->last_subpart_partno &&
          ppar->cur_subpart_fields == ppar->subpart_fields)
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      {
        /* 
          Ok, we've got "fieldN<=>constN"-type SEL_ARGs for all subpartitioning
          fields. Save all constN constants into table record buffer.
        */
        store_selargs_to_rec(ppar, ppar->arg_stack_end - ppar->subpart_fields,
                             ppar->subpart_fields);
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        DBUG_EXECUTE("info", dbug_print_singlepoint_range(ppar->arg_stack_end- 
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                                                       ppar->subpart_fields,
                                                       ppar->subpart_fields););
        /* Find the subpartition (it's HASH/KEY so we always have one) */
        partition_info *part_info= ppar->part_info;
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        uint32 part_id, subpart_id;
                 
        if (part_info->get_subpartition_id(part_info, &subpart_id))
          return 0;

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        /* Mark this partition as used in each subpartition. */
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        while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) !=
                NOT_A_PARTITION_ID)
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        {
          bitmap_set_bit(&part_info->used_partitions,
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                         part_id * part_info->no_subparts + subpart_id);
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        }
        res= 1; /* Some partitions were marked as used */
        goto pop_and_go_right;
      }
    }
    else
    {
      /* 
        Can't handle condition on current key part. If we're that deep that 
        we're processing subpartititoning's key parts, this means we'll not be
        able to infer any suitable condition, so bail out.
      */
      if (partno >= ppar->last_part_partno)
        return -1;
    }
  }

process_next_key_part:
  if (key_tree->next_key_part)
    res= find_used_partitions(ppar, key_tree->next_key_part);
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  else
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    res= -1;
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  if (set_full_part_if_bad_ret)
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  {
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    if (res == -1)
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    {
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      /* Got "full range" for subpartitioning fields */
      uint32 part_id;
      bool found= FALSE;
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      while ((part_id= ppar->part_iter.get_next(&ppar->part_iter)) !=
             NOT_A_PARTITION_ID)
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      {
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        ppar->mark_full_partition_used(ppar->part_info, part_id);
        found= TRUE;
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      }
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      res= test(found);
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    }
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    /*
      Restore the "used partitions iterator" to the default setting that
      specifies iteration over all partitions.
    */
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    init_all_partitions_iterator(ppar->part_info, &ppar->part_iter);
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  }

  if (pushed)
  {
pop_and_go_right:
    /* Pop this key part info off the "stack" */
    ppar->arg_stack_end--;
    ppar->cur_part_fields-=    ppar->is_part_keypart[partno];
    ppar->cur_subpart_fields-= ppar->is_subpart_keypart[partno];
  }
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  if (res == -1)
    return -1;
go_right:
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  if (key_tree->right != &null_element)
  {
    if (-1 == (right_res= find_used_partitions(ppar,key_tree->right)))
      return -1;
  }
  return (left_res || right_res || res);
}
 

static void mark_all_partitions_as_used(partition_info *part_info)
{
  bitmap_set_all(&part_info->used_partitions);
}


/*
  Check if field types allow to construct partitioning index description
 
  SYNOPSIS
    fields_ok_for_partition_index()
      pfield  NULL-terminated array of pointers to fields.

  DESCRIPTION
    For an array of fields, check if we can use all of the fields to create
    partitioning index description.
    
    We can't process GEOMETRY fields - for these fields singlepoint intervals
    cant be generated, and non-singlepoint are "special" kinds of intervals
    to which our processing logic can't be applied.

    It is not known if we could process ENUM fields, so they are disabled to be
    on the safe side.

  RETURN 
    TRUE   Yes, fields can be used in partitioning index
    FALSE  Otherwise
*/

static bool fields_ok_for_partition_index(Field **pfield)
{
  if (!pfield)
    return FALSE;
  for (; (*pfield); pfield++)
  {
    enum_field_types ftype= (*pfield)->real_type();
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    if (ftype == MYSQL_TYPE_ENUM || ftype == MYSQL_TYPE_GEOMETRY)
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      return FALSE;
  }
  return TRUE;
}


/*
  Create partition index description and fill related info in the context
  struct

  SYNOPSIS
3349
    create_partition_index_description()
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      prune_par  INOUT Partition pruning context

  DESCRIPTION
    Create partition index description. Partition index description is:

      part_index(used_fields_list(part_expr), used_fields_list(subpart_expr))

    If partitioning/sub-partitioning uses BLOB or Geometry fields, then
    corresponding fields_list(...) is not included into index description
    and we don't perform partition pruning for partitions/subpartitions.

  RETURN
    TRUE   Out of memory or can't do partition pruning at all
    FALSE  OK
*/

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static bool create_partition_index_description(PART_PRUNE_PARAM *ppar)
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{
  RANGE_OPT_PARAM *range_par= &(ppar->range_param);
  partition_info *part_info= ppar->part_info;
  uint used_part_fields, used_subpart_fields;

  used_part_fields= fields_ok_for_partition_index(part_info->part_field_array) ?
                      part_info->no_part_fields : 0;
  used_subpart_fields= 
    fields_ok_for_partition_index(part_info->subpart_field_array)? 
      part_info->no_subpart_fields : 0;
  
  uint total_parts= used_part_fields + used_subpart_fields;

  ppar->part_fields=      used_part_fields;
  ppar->last_part_partno= (int)used_part_fields - 1;

  ppar->subpart_fields= used_subpart_fields;
  ppar->last_subpart_partno= 
    used_subpart_fields?(int)(used_part_fields + used_subpart_fields - 1): -1;

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  if (part_info->is_sub_partitioned())
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  {
    ppar->mark_full_partition_used=  mark_full_partition_used_with_parts;
    ppar->get_top_partition_id_func= part_info->get_part_partition_id;
  }
  else
  {
    ppar->mark_full_partition_used=  mark_full_partition_used_no_parts;
    ppar->get_top_partition_id_func= part_info->get_partition_id;
  }

  KEY_PART *key_part;
  MEM_ROOT *alloc= range_par->mem_root;
  if (!total_parts || 
      !(key_part= (KEY_PART*)alloc_root(alloc, sizeof(KEY_PART)*
                                               total_parts)) ||
      !(ppar->arg_stack= (SEL_ARG**)alloc_root(alloc, sizeof(SEL_ARG*)* 
                                                      total_parts)) ||
      !(ppar->is_part_keypart= (my_bool*)alloc_root(alloc, sizeof(my_bool)*
                                                           total_parts)) ||
      !(ppar->is_subpart_keypart= (my_bool*)alloc_root(alloc, sizeof(my_bool)*
                                                           total_parts)))
    return TRUE;
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  if (ppar->subpart_fields)
  {
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    my_bitmap_map *buf;
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    uint32 bufsize= bitmap_buffer_size(ppar->part_info->no_subparts);
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    if (!(buf= (my_bitmap_map*) alloc_root(alloc, bufsize)))
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      return TRUE;
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    bitmap_init(&ppar->subparts_bitmap, buf, ppar->part_info->no_subparts,
                FALSE);
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  }
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  range_par->key_parts= key_part;
  Field **field= (ppar->part_fields)? part_info->part_field_array :
                                           part_info->subpart_field_array;
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  bool in_subpart_fields= FALSE;
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  for (uint part= 0; part < total_parts; part++, key_part++)
  {
    key_part->key=          0;
    key_part->part=	    part;
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    key_part->store_length= key_part->length= (uint16) (*field)->key_length();
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    if ((*field)->real_maybe_null())
      key_part->store_length+= HA_KEY_NULL_LENGTH;
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    if ((*field)->type() == MYSQL_TYPE_BLOB || 
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        (*field)->real_type() == MYSQL_TYPE_VARCHAR)
      key_part->store_length+= HA_KEY_BLOB_LENGTH;

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    DBUG_PRINT("info", ("part %u length %u store_length %u", part,
                         key_part->length, key_part->store_length));

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    key_part->field=        (*field);
    key_part->image_type =  Field::itRAW;
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    /* 
      We set keypart flag to 0 here as the only HA_PART_KEY_SEG is checked
      in the RangeAnalysisModule.
    */
    key_part->flag=         0;
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    /* We don't set key_parts->null_bit as it will not be used */

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    ppar->is_part_keypart[part]= !in_subpart_fields;
    ppar->is_subpart_keypart[part]= in_subpart_fields;
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    /*
      Check if this was last field in this array, in this case we
      switch to subpartitioning fields. (This will only happens if
      there are subpartitioning fields to cater for).
    */
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    if (!*(++field))
    {
      field= part_info->subpart_field_array;
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      in_subpart_fields= TRUE;
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    }
  }
  range_par->key_parts_end= key_part;

  DBUG_EXECUTE("info", print_partitioning_index(range_par->key_parts,
                                                range_par->key_parts_end););
  return FALSE;
}


#ifndef DBUG_OFF

static void print_partitioning_index(KEY_PART *parts, KEY_PART *parts_end)
{
  DBUG_ENTER("print_partitioning_index");
  DBUG_LOCK_FILE;
  fprintf(DBUG_FILE, "partitioning INDEX(");
  for (KEY_PART *p=parts; p != parts_end; p++)
  {
    fprintf(DBUG_FILE, "%s%s", p==parts?"":" ,", p->field->field_name);
  }
3480
  fputs(");\n", DBUG_FILE);
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  DBUG_UNLOCK_FILE;
  DBUG_VOID_RETURN;
}

/* Print field value into debug trace, in NULL-aware way. */
static void dbug_print_field(Field *field)
{
  if (field->is_real_null())
    fprintf(DBUG_FILE, "NULL");
  else
  {
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    char buf[256];
    String str(buf, sizeof(buf), &my_charset_bin);
    str.length(0);
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    String *pstr;
    pstr= field->val_str(&str);
    fprintf(DBUG_FILE, "'%s'", pstr->c_ptr_safe());
  }
}


/* Print a "c1 < keypartX < c2" - type interval into debug trace. */
static void dbug_print_segment_range(SEL_ARG *arg, KEY_PART *part)
{
  DBUG_ENTER("dbug_print_segment_range");
  DBUG_LOCK_FILE;
  if (!(arg->min_flag & NO_MIN_RANGE))
  {
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    store_key_image_to_rec(part->field, arg->min_value, part->length);
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    dbug_print_field(part->field);
    if (arg->min_flag & NEAR_MIN)
      fputs(" < ", DBUG_FILE);
    else
      fputs(" <= ", DBUG_FILE);
  }

  fprintf(DBUG_FILE, "%s", part->field->field_name);

  if (!(arg->max_flag & NO_MAX_RANGE))
  {
    if (arg->max_flag & NEAR_MAX)
      fputs(" < ", DBUG_FILE);
    else
      fputs(" <= ", DBUG_FILE);
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    store_key_image_to_rec(part->field, arg->max_value, part->length);
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    dbug_print_field(part->field);
  }
3528
  fputs("\n", DBUG_FILE);
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  DBUG_UNLOCK_FILE;
  DBUG_VOID_RETURN;
}


/*
  Print a singlepoint multi-keypart range interval to debug trace
 
  SYNOPSIS
3538
    dbug_print_singlepoint_range()
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      start  Array of SEL_ARG* ptrs representing conditions on key parts
      num    Number of elements in the array.

  DESCRIPTION
    This function prints a "keypartN=constN AND ... AND keypartK=constK"-type 
    interval to debug trace.
*/

3547
static void dbug_print_singlepoint_range(SEL_ARG **start, uint num)
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{
3549
  DBUG_ENTER("dbug_print_singlepoint_range");
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  DBUG_LOCK_FILE;
  SEL_ARG **end= start + num;
3552

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  for (SEL_ARG **arg= start; arg != end; arg++)
  {
    Field *field= (*arg)->field;
    fprintf(DBUG_FILE, "%s%s=", (arg==start)?"":", ", field->field_name);
    dbug_print_field(field);
  }
3559
  fputs("\n", DBUG_FILE);
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  DBUG_UNLOCK_FILE;
  DBUG_VOID_RETURN;
}
#endif

/****************************************************************************
 * Partition pruning code ends
 ****************************************************************************/
#endif

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/*
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  Get cost of 'sweep' full records retrieval.
  SYNOPSIS
    get_sweep_read_cost()
      param            Parameter from test_quick_select
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      records          # of records to be retrieved
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  RETURN
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    cost of sweep
3579
*/
3580

3581
double get_sweep_read_cost(const PARAM *param, ha_rows records)
3582
{
3583
  double result;
3584
  DBUG_ENTER("get_sweep_read_cost");
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  if (param->table->file->primary_key_is_clustered())
  {
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    result= param->table->file->read_time(param->table->s->primary_key,
3588
                                          (uint)records, records);
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  }
  else
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  {
3592
    double n_blocks=
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      ceil(ulonglong2double(param->table->file->stats.data_file_length) /
           IO_SIZE);
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    double busy_blocks=
      n_blocks * (1.0 - pow(1.0 - 1.0/n_blocks, rows2double(records)));
    if (busy_blocks < 1.0)
      busy_blocks= 1.0;
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    DBUG_PRINT("info",("sweep: nblocks: %g, busy_blocks: %g", n_blocks,
3600
                       busy_blocks));
3601
    /*
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      Disabled: Bail out if # of blocks to read is bigger than # of blocks in
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      table data file.
    if (max_cost != DBL_MAX  && (busy_blocks+index_reads_cost) >= n_blocks)
      return 1;
    */
    JOIN *join= param->thd->lex->select_lex.join;
    if (!join || join->tables == 1)
    {
      /* No join, assume reading is done in one 'sweep' */
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      result= busy_blocks*(DISK_SEEK_BASE_COST +
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                          DISK_SEEK_PROP_COST*n_blocks/busy_blocks);
    }
    else
    {
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      /*
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        Possibly this is a join with source table being non-last table, so
        assume that disk seeks are random here.
      */
3620
      result= busy_blocks;
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    }
  }
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  DBUG_PRINT("return",("cost: %g", result));
3624
  DBUG_RETURN(result);
3625
}
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/*
  Get best plan for a SEL_IMERGE disjunctive expression.
  SYNOPSIS
    get_best_disjunct_quick()
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      param     Parameter from check_quick_select function
      imerge    Expression to use
3634
      read_time Don't create scans with cost > read_time
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3636
  NOTES
3637
    index_merge cost is calculated as follows:
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    index_merge_cost =
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      cost(index_reads) +         (see #1)
      cost(rowid_to_row_scan) +   (see #2)
      cost(unique_use)            (see #3)

    1. cost(index_reads) =SUM_i(cost(index_read_i))
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       For non-CPK scans,
         cost(index_read_i) = {cost of ordinary 'index only' scan}
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       For CPK scan,
         cost(index_read_i) = {cost of non-'index only' scan}

    2. cost(rowid_to_row_scan)
      If table PK is clustered then
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        cost(rowid_to_row_scan) =
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          {cost of ordinary clustered PK scan with n_ranges=n_rows}
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      Otherwise, we use the following model to calculate costs:
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      We need to retrieve n_rows rows from file that occupies n_blocks blocks.
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      We assume that offsets of rows we need are independent variates with
3657
      uniform distribution in [0..max_file_offset] range.
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      We'll denote block as "busy" if it contains row(s) we need to retrieve
      and "empty" if doesn't contain rows we need.
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3662
      Probability that a block is empty is (1 - 1/n_blocks)^n_rows (this
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      applies to any block in file). Let x_i be a variate taking value 1 if
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      block #i is empty and 0 otherwise.
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3666 3667
      Then E(x_i) = (1 - 1/n_blocks)^n_rows;

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      E(n_empty_blocks) = E(sum(x_i)) = sum(E(x_i)) =
        = n_blocks * ((1 - 1/n_blocks)^n_rows) =
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       ~= n_blocks * exp(-n_rows/n_blocks).

      E(n_busy_blocks) = n_blocks*(1 - (1 - 1/n_blocks)^n_rows) =
       ~= n_blocks * (1 - exp(-n_rows/n_blocks)).
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      Average size of "hole" between neighbor non-empty blocks is
           E(hole_size) = n_blocks/E(n_busy_blocks).
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      The total cost of reading all needed blocks in one "sweep" is:

      E(n_busy_blocks)*
       (DISK_SEEK_BASE_COST + DISK_SEEK_PROP_COST*n_blocks/E(n_busy_blocks)).

    3. Cost of Unique use is calculated in Unique::get_use_cost function.
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  ROR-union cost is calculated in the same way index_merge, but instead of
  Unique a priority queue is used.

  RETURN
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    Created read plan
    NULL - Out of memory or no read scan could be built.
3691
*/
3692

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static
TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge,
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                                         double read_time)
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{
  SEL_TREE **ptree;
  TRP_INDEX_MERGE *imerge_trp= NULL;
  uint n_child_scans= imerge->trees_next - imerge->trees;
  TRP_RANGE **range_scans;
  TRP_RANGE **cur_child;
  TRP_RANGE **cpk_scan= NULL;
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  bool imerge_too_expensive= FALSE;
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  double imerge_cost= 0.0;
  ha_rows cpk_scan_records= 0;
  ha_rows non_cpk_scan_records= 0;
  bool pk_is_clustered= param->table->file->primary_key_is_clustered();
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  bool all_scans_ror_able= TRUE;
  bool all_scans_rors= TRUE;
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  uint unique_calc_buff_size;
  TABLE_READ_PLAN **roru_read_plans;
  TABLE_READ_PLAN **cur_roru_plan;
  double roru_index_costs;
  ha_rows roru_total_records;
  double roru_intersect_part= 1.0;
  DBUG_ENTER("get_best_disjunct_quick");
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  DBUG_PRINT("info", ("Full table scan cost: %g", read_time));
3718

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  if (!(range_scans= (TRP_RANGE**)alloc_root(param->mem_root,
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                                             sizeof(TRP_RANGE*)*
                                             n_child_scans)))
    DBUG_RETURN(NULL);
3723
  /*
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    Collect best 'range' scan for each of disjuncts, and, while doing so,
    analyze possibility of ROR scans. Also calculate some values needed by
    other parts of the code.
3727
  */
3728
  for (ptree= imerge->trees, cur_child= range_scans;
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       ptree != imerge->trees_next;
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       ptree++, cur_child++)
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  {
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    DBUG_EXECUTE("info", print_sel_tree(param, *ptree, &(*ptree)->keys_map,
                                        "tree in SEL_IMERGE"););
3734
    if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, FALSE, read_time)))
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    {
      /*
3737
        One of index scans in this index_merge is more expensive than entire
3738 3739 3740
        table read for another available option. The entire index_merge (and
        any possible ROR-union) will be more expensive then, too. We continue
        here only to update SQL_SELECT members.
3741
      */
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      imerge_too_expensive= TRUE;
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    }
    if (imerge_too_expensive)
      continue;
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3747 3748 3749
    imerge_cost += (*cur_child)->read_cost;
    all_scans_ror_able &= ((*ptree)->n_ror_scans > 0);
    all_scans_rors &= (*cur_child)->is_ror;
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3750
    if (pk_is_clustered &&
3751 3752
        param->real_keynr[(*cur_child)->key_idx] ==
        param->table->s->primary_key)
3753
    {
3754 3755
      cpk_scan= cur_child;
      cpk_scan_records= (*cur_child)->records;
3756 3757
    }
    else
3758
      non_cpk_scan_records += (*cur_child)->records;
3759
  }
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3760

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  DBUG_PRINT("info", ("index_merge scans cost %g", imerge_cost));
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  if (imerge_too_expensive || (imerge_cost > read_time) ||
3763
      (non_cpk_scan_records+cpk_scan_records >= param->table->file->stats.records) &&
3764
      read_time != DBL_MAX)
3765
  {
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    /*
      Bail out if it is obvious that both index_merge and ROR-union will be
3768
      more expensive
3769
    */
3770 3771
    DBUG_PRINT("info", ("Sum of index_merge scans is more expensive than "
                        "full table scan, bailing out"));
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    DBUG_RETURN(NULL);
3773
  }
3774 3775 3776 3777 3778 3779 3780

  /* 
    If all scans happen to be ROR, proceed to generate a ROR-union plan (it's 
    guaranteed to be cheaper than non-ROR union), unless ROR-unions are
    disabled in @@optimizer_switch
  */
  if (all_scans_rors && 
3781
      optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_UNION))
3782
  {
3783 3784
    roru_read_plans= (TABLE_READ_PLAN**)range_scans;
    goto skip_to_ror_scan;
3785
  }
3786

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3787 3788
  if (cpk_scan)
  {
3789 3790
    /*
      Add one ROWID comparison for each row retrieved on non-CPK scan.  (it
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3791 3792 3793
      is done in QUICK_RANGE_SELECT::row_in_ranges)
     */
    imerge_cost += non_cpk_scan_records / TIME_FOR_COMPARE_ROWID;
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  }

  /* Calculate cost(rowid_to_row_scan) */
3797
  imerge_cost += get_sweep_read_cost(param, non_cpk_scan_records);
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  DBUG_PRINT("info",("index_merge cost with rowid-to-row scan: %g",
3799
                     imerge_cost));
3800
  if (imerge_cost > read_time || 
3801
      !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_SORT_UNION))
3802
  {
3803
    goto build_ror_index_merge;
3804
  }
3805 3806

  /* Add Unique operations cost */
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  unique_calc_buff_size=
3808
    Unique::get_cost_calc_buff_size((ulong)non_cpk_scan_records,
3809 3810 3811 3812 3813 3814
                                    param->table->file->ref_length,
                                    param->thd->variables.sortbuff_size);
  if (param->imerge_cost_buff_size < unique_calc_buff_size)
  {
    if (!(param->imerge_cost_buff= (uint*)alloc_root(param->mem_root,
                                                     unique_calc_buff_size)))
3815
      DBUG_RETURN(NULL);
3816 3817 3818
    param->imerge_cost_buff_size= unique_calc_buff_size;
  }

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3819
  imerge_cost +=
3820
    Unique::get_use_cost(param->imerge_cost_buff, (uint)non_cpk_scan_records,
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3821 3822
                         param->table->file->ref_length,
                         param->thd->variables.sortbuff_size);
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  DBUG_PRINT("info",("index_merge total cost: %g (wanted: less then %g)",
3824 3825 3826 3827 3828 3829 3830
                     imerge_cost, read_time));
  if (imerge_cost < read_time)
  {
    if ((imerge_trp= new (param->mem_root)TRP_INDEX_MERGE))
    {
      imerge_trp->read_cost= imerge_cost;
      imerge_trp->records= non_cpk_scan_records + cpk_scan_records;
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      imerge_trp->records= min(imerge_trp->records,
3832
                               param->table->file->stats.records);
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      imerge_trp->range_scans= range_scans;
      imerge_trp->range_scans_end= range_scans + n_child_scans;
      read_time= imerge_cost;
    }
  }
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3838

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build_ror_index_merge:
3840 3841
  if (!all_scans_ror_able || 
      param->thd->lex->sql_command == SQLCOM_DELETE ||
3842
      !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_UNION))
3843
    DBUG_RETURN(imerge_trp);
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3844

3845 3846
  /* Ok, it is possible to build a ROR-union, try it. */
  bool dummy;
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  if (!(roru_read_plans=
3848 3849 3850 3851 3852 3853 3854 3855 3856 3857 3858 3859 3860
          (TABLE_READ_PLAN**)alloc_root(param->mem_root,
                                        sizeof(TABLE_READ_PLAN*)*
                                        n_child_scans)))
    DBUG_RETURN(imerge_trp);
skip_to_ror_scan:
  roru_index_costs= 0.0;
  roru_total_records= 0;
  cur_roru_plan= roru_read_plans;

  /* Find 'best' ROR scan for each of trees in disjunction */
  for (ptree= imerge->trees, cur_child= range_scans;
       ptree != imerge->trees_next;
       ptree++, cur_child++, cur_roru_plan++)
3861
  {
3862 3863
    /*
      Assume the best ROR scan is the one that has cheapest full-row-retrieval
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3864 3865
      scan cost.
      Also accumulate index_only scan costs as we'll need them to calculate
3866 3867 3868 3869 3870 3871 3872
      overall index_intersection cost.
    */
    double cost;
    if ((*cur_child)->is_ror)
    {
      /* Ok, we have index_only cost, now get full rows scan cost */
      cost= param->table->file->
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              read_time(param->real_keynr[(*cur_child)->key_idx], 1,
3874 3875 3876 3877 3878 3879 3880
                        (*cur_child)->records) +
              rows2double((*cur_child)->records) / TIME_FOR_COMPARE;
    }
    else
      cost= read_time;

    TABLE_READ_PLAN *prev_plan= *cur_child;
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    if (!(*cur_roru_plan= get_best_ror_intersect(param, *ptree, cost,
3882 3883 3884 3885 3886 3887 3888 3889 3890
                                                 &dummy)))
    {
      if (prev_plan->is_ror)
        *cur_roru_plan= prev_plan;
      else
        DBUG_RETURN(imerge_trp);
      roru_index_costs += (*cur_roru_plan)->read_cost;
    }
    else
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3891 3892
      roru_index_costs +=
        ((TRP_ROR_INTERSECT*)(*cur_roru_plan))->index_scan_costs;
3893
    roru_total_records += (*cur_roru_plan)->records;
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    roru_intersect_part *= (*cur_roru_plan)->records /
3895
                           param->table->file->stats.records;
3896
  }
3897

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  /*
    rows to retrieve=
3900
      SUM(rows_in_scan_i) - table_rows * PROD(rows_in_scan_i / table_rows).
3901
    This is valid because index_merge construction guarantees that conditions
3902 3903 3904
    in disjunction do not share key parts.
  */
  roru_total_records -= (ha_rows)(roru_intersect_part*
3905
                                  param->table->file->stats.records);
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  /* ok, got a ROR read plan for each of the disjuncts
    Calculate cost:
3908 3909 3910 3911 3912 3913
    cost(index_union_scan(scan_1, ... scan_n)) =
      SUM_i(cost_of_index_only_scan(scan_i)) +
      queue_use_cost(rowid_len, n) +
      cost_of_row_retrieval
    See get_merge_buffers_cost function for queue_use_cost formula derivation.
  */
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3914

3915
  double roru_total_cost;
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  roru_total_cost= roru_index_costs +
                   rows2double(roru_total_records)*log((double)n_child_scans) /
                   (TIME_FOR_COMPARE_ROWID * M_LN2) +
3919 3920
                   get_sweep_read_cost(param, roru_total_records);

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  DBUG_PRINT("info", ("ROR-union: cost %g, %d members", roru_total_cost,
3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934 3935
                      n_child_scans));
  TRP_ROR_UNION* roru;
  if (roru_total_cost < read_time)
  {
    if ((roru= new (param->mem_root) TRP_ROR_UNION))
    {
      roru->first_ror= roru_read_plans;
      roru->last_ror= roru_read_plans + n_child_scans;
      roru->read_cost= roru_total_cost;
      roru->records= roru_total_records;
      DBUG_RETURN(roru);
    }
  }
  DBUG_RETURN(imerge_trp);
3936 3937 3938 3939 3940 3941 3942
}


/*
  Calculate cost of 'index only' scan for given index and number of records.

  SYNOPSIS
3943
    get_index_only_read_time()
3944 3945 3946 3947 3948
      param    parameters structure
      records  #of records to read
      keynr    key to read

  NOTES
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3949
    It is assumed that we will read trough the whole key range and that all
3950 3951 3952 3953
    key blocks are half full (normally things are much better). It is also
    assumed that each time we read the next key from the index, the handler
    performs a random seek, thus the cost is proportional to the number of
    blocks read.
3954 3955 3956 3957 3958 3959

  TODO:
    Move this to handler->read_time() by adding a flag 'index-only-read' to
    this call. The reason for doing this is that the current function doesn't
    handle the case when the row is stored in the b-tree (like in innodb
    clustered index)
3960 3961
*/

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3962
static double get_index_only_read_time(const PARAM* param, ha_rows records,
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3963
                                       int keynr)
3964 3965
{
  double read_time;
3966
  uint keys_per_block= (param->table->file->stats.block_size/2/
3967 3968 3969 3970
			(param->table->key_info[keynr].key_length+
			 param->table->file->ref_length) + 1);
  read_time=((double) (records+keys_per_block-1)/
             (double) keys_per_block);
3971
  return read_time;
3972 3973
}

3974

3975 3976
typedef struct st_ror_scan_info
{
3977 3978 3979 3980 3981
  uint      idx;      /* # of used key in param->keys */
  uint      keynr;    /* # of used key in table */
  ha_rows   records;  /* estimate of # records this scan will return */

  /* Set of intervals over key fields that will be used for row retrieval. */
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  SEL_ARG   *sel_arg;
3983 3984

  /* Fields used in the query and covered by this ROR scan. */
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3985 3986
  MY_BITMAP covered_fields;
  uint      used_fields_covered; /* # of set bits in covered_fields */
3987
  int       key_rec_length; /* length of key record (including rowid) */
3988 3989

  /*
3990 3991
    Cost of reading all index records with values in sel_arg intervals set
    (assuming there is no need to access full table records)
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3992 3993
  */
  double    index_read_cost;
3994 3995 3996
  uint      first_uncovered_field; /* first unused bit in covered_fields */
  uint      key_components; /* # of parts in the key */
} ROR_SCAN_INFO;
3997 3998 3999


/*
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  Create ROR_SCAN_INFO* structure with a single ROR scan on index idx using
4001
  sel_arg set of intervals.
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4002

4003 4004
  SYNOPSIS
    make_ror_scan()
4005 4006 4007
      param    Parameter from test_quick_select function
      idx      Index of key in param->keys
      sel_arg  Set of intervals for a given key
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4008

4009
  RETURN
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4010
    NULL - out of memory
4011
    ROR scan structure containing a scan for {idx, sel_arg}
4012 4013 4014 4015 4016 4017
*/

static
ROR_SCAN_INFO *make_ror_scan(const PARAM *param, int idx, SEL_ARG *sel_arg)
{
  ROR_SCAN_INFO *ror_scan;
4018
  my_bitmap_map *bitmap_buf;
4019 4020
  uint keynr;
  DBUG_ENTER("make_ror_scan");
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4021

4022 4023 4024 4025 4026 4027
  if (!(ror_scan= (ROR_SCAN_INFO*)alloc_root(param->mem_root,
                                             sizeof(ROR_SCAN_INFO))))
    DBUG_RETURN(NULL);

  ror_scan->idx= idx;
  ror_scan->keynr= keynr= param->real_keynr[idx];
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  ror_scan->key_rec_length= (param->table->key_info[keynr].key_length +
                             param->table->file->ref_length);
4030 4031
  ror_scan->sel_arg= sel_arg;
  ror_scan->records= param->table->quick_rows[keynr];
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4032

4033 4034
  if (!(bitmap_buf= (my_bitmap_map*) alloc_root(param->mem_root,
                                                param->fields_bitmap_size)))
4035
    DBUG_RETURN(NULL);
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4036

4037
  if (bitmap_init(&ror_scan->covered_fields, bitmap_buf,
4038
                  param->table->s->fields, FALSE))
4039 4040
    DBUG_RETURN(NULL);
  bitmap_clear_all(&ror_scan->covered_fields);
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4041

4042
  KEY_PART_INFO *key_part= param->table->key_info[keynr].key_part;
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  KEY_PART_INFO *key_part_end= key_part +
4044 4045 4046
                               param->table->key_info[keynr].key_parts;
  for (;key_part != key_part_end; ++key_part)
  {
4047 4048
    if (bitmap_is_set(&param->needed_fields, key_part->fieldnr-1))
      bitmap_set_bit(&ror_scan->covered_fields, key_part->fieldnr-1);
4049
  }
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4050
  ror_scan->index_read_cost=
4051 4052 4053 4054 4055 4056
    get_index_only_read_time(param, param->table->quick_rows[ror_scan->keynr],
                             ror_scan->keynr);
  DBUG_RETURN(ror_scan);
}


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4057
/*
4058 4059 4060 4061 4062 4063 4064
  Compare two ROR_SCAN_INFO** by  E(#records_matched) * key_record_length.
  SYNOPSIS
    cmp_ror_scan_info()
      a ptr to first compared value
      b ptr to second compared value

  RETURN
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   -1 a < b
4066 4067
    0 a = b
    1 a > b
4068
*/
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4069

4070
static int cmp_ror_scan_info(ROR_SCAN_INFO** a, ROR_SCAN_INFO** b)
4071 4072 4073 4074 4075 4076 4077
{
  double val1= rows2double((*a)->records) * (*a)->key_rec_length;
  double val2= rows2double((*b)->records) * (*b)->key_rec_length;
  return (val1 < val2)? -1: (val1 == val2)? 0 : 1;
}

/*
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4078 4079 4080
  Compare two ROR_SCAN_INFO** by
   (#covered fields in F desc,
    #components asc,
4081
    number of first not covered component asc)
4082 4083 4084 4085 4086 4087 4088

  SYNOPSIS
    cmp_ror_scan_info_covering()
      a ptr to first compared value
      b ptr to second compared value

  RETURN
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   -1 a < b
4090 4091
    0 a = b
    1 a > b
4092
*/
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4093

4094
static int cmp_ror_scan_info_covering(ROR_SCAN_INFO** a, ROR_SCAN_INFO** b)
4095 4096 4097 4098 4099 4100 4101 4102 4103 4104 4105 4106 4107 4108 4109 4110
{
  if ((*a)->used_fields_covered > (*b)->used_fields_covered)
    return -1;
  if ((*a)->used_fields_covered < (*b)->used_fields_covered)
    return 1;
  if ((*a)->key_components < (*b)->key_components)
    return -1;
  if ((*a)->key_components > (*b)->key_components)
    return 1;
  if ((*a)->first_uncovered_field < (*b)->first_uncovered_field)
    return -1;
  if ((*a)->first_uncovered_field > (*b)->first_uncovered_field)
    return 1;
  return 0;
}

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4111

4112
/* Auxiliary structure for incremental ROR-intersection creation */
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4113
typedef struct
4114 4115 4116
{
  const PARAM *param;
  MY_BITMAP covered_fields; /* union of fields covered by all scans */
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4117
  /*
4118
    Fraction of table records that satisfies conditions of all scans.
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4119
    This is the number of full records that will be retrieved if a
4120 4121
    non-index_only index intersection will be employed.
  */
4122 4123 4124 4125
  double out_rows;
  /* TRUE if covered_fields is a superset of needed_fields */
  bool is_covering;

4126
  ha_rows index_records; /* sum(#records to look in indexes) */
4127 4128
  double index_scan_costs; /* SUM(cost of 'index-only' scans) */
  double total_cost;
4129
} ROR_INTERSECT_INFO;
4130 4131


4132 4133 4134 4135
/*
  Allocate a ROR_INTERSECT_INFO and initialize it to contain zero scans.

  SYNOPSIS
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4136 4137 4138
    ror_intersect_init()
      param         Parameter from test_quick_select

4139 4140 4141 4142 4143 4144
  RETURN
    allocated structure
    NULL on error
*/

static
4145
ROR_INTERSECT_INFO* ror_intersect_init(const PARAM *param)
4146 4147
{
  ROR_INTERSECT_INFO *info;
4148
  my_bitmap_map* buf;
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  if (!(info= (ROR_INTERSECT_INFO*)alloc_root(param->mem_root,
4150 4151 4152
                                              sizeof(ROR_INTERSECT_INFO))))
    return NULL;
  info->param= param;
4153 4154
  if (!(buf= (my_bitmap_map*) alloc_root(param->mem_root,
                                         param->fields_bitmap_size)))
4155
    return NULL;
4156
  if (bitmap_init(&info->covered_fields, buf, param->table->s->fields,
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4157
                  FALSE))
4158
    return NULL;
4159
  info->is_covering= FALSE;
4160
  info->index_scan_costs= 0.0;
4161
  info->index_records= 0;
4162
  info->out_rows= (double) param->table->file->stats.records;
4163
  bitmap_clear_all(&info->covered_fields);
4164 4165 4166
  return info;
}

4167 4168 4169 4170
void ror_intersect_cpy(ROR_INTERSECT_INFO *dst, const ROR_INTERSECT_INFO *src)
{
  dst->param= src->param;
  memcpy(dst->covered_fields.bitmap, src->covered_fields.bitmap, 
4171
         no_bytes_in_map(&src->covered_fields));
4172 4173 4174 4175 4176 4177
  dst->out_rows= src->out_rows;
  dst->is_covering= src->is_covering;
  dst->index_records= src->index_records;
  dst->index_scan_costs= src->index_scan_costs;
  dst->total_cost= src->total_cost;
}
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4178 4179


4180
/*
4181
  Get selectivity of a ROR scan wrt ROR-intersection.
4182

4183
  SYNOPSIS
4184 4185 4186 4187
    ror_scan_selectivity()
      info  ROR-interection 
      scan  ROR scan
      
4188
  NOTES
4189
    Suppose we have a condition on several keys
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4190 4191
    cond=k_11=c_11 AND k_12=c_12 AND ...  // parts of first key
         k_21=c_21 AND k_22=c_22 AND ...  // parts of second key
4192
          ...
4193
         k_n1=c_n1 AND k_n3=c_n3 AND ...  (1) //parts of the key used by *scan
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4194

4195 4196
    where k_ij may be the same as any k_pq (i.e. keys may have common parts).

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    A full row is retrieved if entire condition holds.
4198 4199

    The recursive procedure for finding P(cond) is as follows:
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4200

4201
    First step:
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4202
    Pick 1st part of 1st key and break conjunction (1) into two parts:
4203 4204
      cond= (k_11=c_11 AND R)

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    Here R may still contain condition(s) equivalent to k_11=c_11.
4206 4207
    Nevertheless, the following holds:

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      P(k_11=c_11 AND R) = P(k_11=c_11) * P(R | k_11=c_11).
4209 4210 4211 4212 4213

    Mark k_11 as fixed field (and satisfied condition) F, save P(F),
    save R to be cond and proceed to recursion step.

    Recursion step:
4214
    We have a set of fixed fields/satisfied conditions) F, probability P(F),
4215 4216 4217
    and remaining conjunction R
    Pick next key part on current key and its condition "k_ij=c_ij".
    We will add "k_ij=c_ij" into F and update P(F).
4218
    Lets denote k_ij as t,  R = t AND R1, where R1 may still contain t. Then
4219

4220
     P((t AND R1)|F) = P(t|F) * P(R1|t|F) = P(t|F) * P(R1|(t AND F)) (2)
4221 4222 4223 4224 4225 4226 4227

    (where '|' mean conditional probability, not "or")

    Consider the first multiplier in (2). One of the following holds:
    a) F contains condition on field used in t (i.e. t AND F = F).
      Then P(t|F) = 1

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    b) F doesn't contain condition on field used in t. Then F and t are
     considered independent.
4230

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4231
     P(t|F) = P(t|(fields_before_t_in_key AND other_fields)) =
4232 4233
          = P(t|fields_before_t_in_key).

4234 4235
     P(t|fields_before_t_in_key) = #records(fields_before_t_in_key) /
                                   #records(fields_before_t_in_key, t)
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4236 4237

    The second multiplier is calculated by applying this step recursively.
4238

4239 4240 4241 4242 4243
  IMPLEMENTATION
    This function calculates the result of application of the "recursion step"
    described above for all fixed key members of a single key, accumulating set
    of covered fields, selectivity, etc.

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4244
    The calculation is conducted as follows:
4245
    Lets denote #records(keypart1, ... keypartK) as n_k. We need to calculate
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4246

4247
     n_{k1}      n_{k2}
4248
    --------- * ---------  * .... (3)
4249
     n_{k1-1}    n_{k2-1}
4250

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4251 4252 4253 4254
    where k1,k2,... are key parts which fields were not yet marked as fixed
    ( this is result of application of option b) of the recursion step for
      parts of a single key).
    Since it is reasonable to expect that most of the fields are not marked
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4255
    as fixed, we calculate (3) as
4256

4257
                                  n_{i1}      n_{i2}
4258
    (3) = n_{max_key_part}  / (   --------- * ---------  * ....  )
4259
                                  n_{i1-1}    n_{i2-1}
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4260 4261 4262

    where i1,i2, .. are key parts that were already marked as fixed.

4263 4264
    In order to minimize number of expensive records_in_range calls we group
    and reduce adjacent fractions.
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4265

4266
  RETURN
4267
    Selectivity of given ROR scan.
4268 4269
*/

4270 4271
static double ror_scan_selectivity(const ROR_INTERSECT_INFO *info, 
                                   const ROR_SCAN_INFO *scan)
4272 4273
{
  double selectivity_mult= 1.0;
4274
  KEY_PART_INFO *key_part= info->param->table->key_info[scan->keynr].key_part;
4275 4276
  uchar key_val[MAX_KEY_LENGTH+MAX_FIELD_WIDTH]; /* key values tuple */
  uchar *key_ptr= key_val;
4277
  SEL_ARG *sel_arg, *tuple_arg= NULL;
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  key_part_map keypart_map= 0;
4279
  bool cur_covered;
4280
  bool prev_covered= test(bitmap_is_set(&info->covered_fields,
4281
                                        key_part->fieldnr-1));
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4282 4283
  key_range min_range;
  key_range max_range;
4284
  min_range.key= key_val;
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  min_range.flag= HA_READ_KEY_EXACT;
4286
  max_range.key= key_val;
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  max_range.flag= HA_READ_AFTER_KEY;
4288
  ha_rows prev_records= info->param->table->file->stats.records;
4289
  DBUG_ENTER("ror_scan_selectivity");
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4290 4291 4292

  for (sel_arg= scan->sel_arg; sel_arg;
       sel_arg= sel_arg->next_key_part)
4293
  {
4294
    DBUG_PRINT("info",("sel_arg step"));
4295
    cur_covered= test(bitmap_is_set(&info->covered_fields,
4296
                                    key_part[sel_arg->part].fieldnr-1));
4297
    if (cur_covered != prev_covered)
4298
    {
4299
      /* create (part1val, ..., part{n-1}val) tuple. */
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4300 4301
      ha_rows records;
      if (!tuple_arg)
4302
      {
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4303 4304
        tuple_arg= scan->sel_arg;
        /* Here we use the length of the first key part */
4305
        tuple_arg->store_min(key_part->store_length, &key_ptr, 0);
4306
        keypart_map= 1;
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4307 4308 4309 4310
      }
      while (tuple_arg->next_key_part != sel_arg)
      {
        tuple_arg= tuple_arg->next_key_part;
4311 4312 4313
        tuple_arg->store_min(key_part[tuple_arg->part].store_length,
                             &key_ptr, 0);
        keypart_map= (keypart_map << 1) | 1;
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4314
      }
4315
      min_range.length= max_range.length= (size_t) (key_ptr - key_val);
4316
      min_range.keypart_map= max_range.keypart_map= keypart_map;
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4317 4318
      records= (info->param->table->file->
                records_in_range(scan->keynr, &min_range, &max_range));
4319 4320 4321 4322 4323 4324 4325 4326 4327 4328 4329
      if (cur_covered)
      {
        /* uncovered -> covered */
        double tmp= rows2double(records)/rows2double(prev_records);
        DBUG_PRINT("info", ("Selectivity multiplier: %g", tmp));
        selectivity_mult *= tmp;
        prev_records= HA_POS_ERROR;
      }
      else
      {
        /* covered -> uncovered */
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        prev_records= records;
4331
      }
4332
    }
4333 4334 4335 4336
    prev_covered= cur_covered;
  }
  if (!prev_covered)
  {
4337
    double tmp= rows2double(info->param->table->quick_rows[scan->keynr]) /
4338 4339
                rows2double(prev_records);
    DBUG_PRINT("info", ("Selectivity multiplier: %g", tmp));
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4340
    selectivity_mult *= tmp;
4341
  }
4342 4343 4344
  DBUG_PRINT("info", ("Returning multiplier: %g", selectivity_mult));
  DBUG_RETURN(selectivity_mult);
}
4345

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4346

4347 4348 4349 4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383
/*
  Check if adding a ROR scan to a ROR-intersection reduces its cost of
  ROR-intersection and if yes, update parameters of ROR-intersection,
  including its cost.

  SYNOPSIS
    ror_intersect_add()
      param        Parameter from test_quick_select
      info         ROR-intersection structure to add the scan to.
      ror_scan     ROR scan info to add.
      is_cpk_scan  If TRUE, add the scan as CPK scan (this can be inferred
                   from other parameters and is passed separately only to
                   avoid duplicating the inference code)

  NOTES
    Adding a ROR scan to ROR-intersect "makes sense" iff the cost of ROR-
    intersection decreases. The cost of ROR-intersection is calculated as
    follows:

    cost= SUM_i(key_scan_cost_i) + cost_of_full_rows_retrieval

    When we add a scan the first increases and the second decreases.

    cost_of_full_rows_retrieval=
      (union of indexes used covers all needed fields) ?
        cost_of_sweep_read(E(rows_to_retrieve), rows_in_table) :
        0

    E(rows_to_retrieve) = #rows_in_table * ror_scan_selectivity(null, scan1) *
                           ror_scan_selectivity({scan1}, scan2) * ... *
                           ror_scan_selectivity({scan1,...}, scanN). 
  RETURN
    TRUE   ROR scan added to ROR-intersection, cost updated.
    FALSE  It doesn't make sense to add this ROR scan to this ROR-intersection.
*/

static bool ror_intersect_add(ROR_INTERSECT_INFO *info,
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4384
                              ROR_SCAN_INFO* ror_scan, bool is_cpk_scan)
4385 4386 4387 4388 4389 4390 4391
{
  double selectivity_mult= 1.0;

  DBUG_ENTER("ror_intersect_add");
  DBUG_PRINT("info", ("Current out_rows= %g", info->out_rows));
  DBUG_PRINT("info", ("Adding scan on %s",
                      info->param->table->key_info[ror_scan->keynr].name));
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4392
  DBUG_PRINT("info", ("is_cpk_scan: %d",is_cpk_scan));
4393 4394

  selectivity_mult = ror_scan_selectivity(info, ror_scan);
4395 4396 4397
  if (selectivity_mult == 1.0)
  {
    /* Don't add this scan if it doesn't improve selectivity. */
4398
    DBUG_PRINT("info", ("The scan doesn't improve selectivity."));
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4399
    DBUG_RETURN(FALSE);
4400
  }
4401 4402 4403
  
  info->out_rows *= selectivity_mult;
  
4404
  if (is_cpk_scan)
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4405
  {
4406 4407 4408 4409 4410 4411
    /*
      CPK scan is used to filter out rows. We apply filtering for 
      each record of every scan. Assuming 1/TIME_FOR_COMPARE_ROWID
      per check this gives us:
    */
    info->index_scan_costs += rows2double(info->index_records) / 
4412 4413 4414 4415
                              TIME_FOR_COMPARE_ROWID;
  }
  else
  {
4416
    info->index_records += info->param->table->quick_rows[ror_scan->keynr];
4417 4418
    info->index_scan_costs += ror_scan->index_read_cost;
    bitmap_union(&info->covered_fields, &ror_scan->covered_fields);
4419 4420 4421 4422 4423 4424
    if (!info->is_covering && bitmap_is_subset(&info->param->needed_fields,
                                               &info->covered_fields))
    {
      DBUG_PRINT("info", ("ROR-intersect is covering now"));
      info->is_covering= TRUE;
    }
4425
  }
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4426

4427
  info->total_cost= info->index_scan_costs;
4428
  DBUG_PRINT("info", ("info->total_cost: %g", info->total_cost));
4429 4430
  if (!info->is_covering)
  {
4431 4432 4433
    info->total_cost += 
      get_sweep_read_cost(info->param, double2rows(info->out_rows));
    DBUG_PRINT("info", ("info->total_cost= %g", info->total_cost));
4434
  }
4435 4436
  DBUG_PRINT("info", ("New out_rows: %g", info->out_rows));
  DBUG_PRINT("info", ("New cost: %g, %scovering", info->total_cost,
4437
                      info->is_covering?"" : "non-"));
4438
  DBUG_RETURN(TRUE);
4439 4440
}

4441

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4442 4443
/*
  Get best ROR-intersection plan using non-covering ROR-intersection search
4444 4445 4446 4447
  algorithm. The returned plan may be covering.

  SYNOPSIS
    get_best_ror_intersect()
4448 4449 4450
      param            Parameter from test_quick_select function.
      tree             Transformed restriction condition to be used to look
                       for ROR scans.
4451
      read_time        Do not return read plans with cost > read_time.
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4452
      are_all_covering [out] set to TRUE if union of all scans covers all
4453 4454
                       fields needed by the query (and it is possible to build
                       a covering ROR-intersection)
4455

4456
  NOTES
4457 4458 4459 4460 4461
    get_key_scans_params must be called before this function can be called.
    
    When this function is called by ROR-union construction algorithm it
    assumes it is building an uncovered ROR-intersection (and thus # of full
    records to be retrieved is wrong here). This is a hack.
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4462

4463
  IMPLEMENTATION
4464
    The approximate best non-covering plan search algorithm is as follows:
4465

4466 4467 4468 4469
    find_min_ror_intersection_scan()
    {
      R= select all ROR scans;
      order R by (E(#records_matched) * key_record_length).
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4470

4471 4472 4473 4474 4475 4476
      S= first(R); -- set of scans that will be used for ROR-intersection
      R= R-first(S);
      min_cost= cost(S);
      min_scan= make_scan(S);
      while (R is not empty)
      {
4477 4478
        firstR= R - first(R);
        if (!selectivity(S + firstR < selectivity(S)))
4479
          continue;
4480
          
4481 4482 4483 4484 4485 4486 4487 4488 4489
        S= S + first(R);
        if (cost(S) < min_cost)
        {
          min_cost= cost(S);
          min_scan= make_scan(S);
        }
      }
      return min_scan;
    }
4490

4491
    See ror_intersect_add function for ROR intersection costs.
4492

4493
    Special handling for Clustered PK scans
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4494 4495
    Clustered PK contains all table fields, so using it as a regular scan in
    index intersection doesn't make sense: a range scan on CPK will be less
4496 4497
    expensive in this case.
    Clustered PK scan has special handling in ROR-intersection: it is not used
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4498
    to retrieve rows, instead its condition is used to filter row references
4499
    we get from scans on other keys.
4500 4501

  RETURN
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4502
    ROR-intersection table read plan
4503
    NULL if out of memory or no suitable plan found.
4504 4505
*/

4506 4507 4508 4509 4510 4511
static
TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree,
                                          double read_time,
                                          bool *are_all_covering)
{
  uint idx;
4512
  double min_cost= DBL_MAX;
4513
  DBUG_ENTER("get_best_ror_intersect");
4514

4515
  if ((tree->n_ror_scans < 2) || !param->table->file->stats.records ||
4516
      !optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_INTERSECT))
4517
    DBUG_RETURN(NULL);
4518 4519

  /*
4520 4521
    Step1: Collect ROR-able SEL_ARGs and create ROR_SCAN_INFO for each of 
    them. Also find and save clustered PK scan if there is one.
4522
  */
4523
  ROR_SCAN_INFO **cur_ror_scan;
4524
  ROR_SCAN_INFO *cpk_scan= NULL;
4525
  uint cpk_no;
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4526
  bool cpk_scan_used= FALSE;
4527

4528 4529 4530 4531
  if (!(tree->ror_scans= (ROR_SCAN_INFO**)alloc_root(param->mem_root,
                                                     sizeof(ROR_SCAN_INFO*)*
                                                     param->keys)))
    return NULL;
4532 4533
  cpk_no= ((param->table->file->primary_key_is_clustered()) ?
           param->table->s->primary_key : MAX_KEY);
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4534

4535
  for (idx= 0, cur_ror_scan= tree->ror_scans; idx < param->keys; idx++)
4536
  {
4537
    ROR_SCAN_INFO *scan;
4538
    if (!tree->ror_scans_map.is_set(idx))
4539
      continue;
4540
    if (!(scan= make_ror_scan(param, idx, tree->keys[idx])))
4541
      return NULL;
4542
    if (param->real_keynr[idx] == cpk_no)
4543
    {
4544 4545
      cpk_scan= scan;
      tree->n_ror_scans--;
4546 4547
    }
    else
4548
      *(cur_ror_scan++)= scan;
4549
  }
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4550

4551
  tree->ror_scans_end= cur_ror_scan;
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4552 4553
  DBUG_EXECUTE("info",print_ror_scans_arr(param->table, "original",
                                          tree->ror_scans,
4554 4555
                                          tree->ror_scans_end););
  /*
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4556
    Ok, [ror_scans, ror_scans_end) is array of ptrs to initialized
4557 4558
    ROR_SCAN_INFO's.
    Step 2: Get best ROR-intersection using an approximate algorithm.
4559
  */
4560 4561
  my_qsort(tree->ror_scans, tree->n_ror_scans, sizeof(ROR_SCAN_INFO*),
           (qsort_cmp)cmp_ror_scan_info);
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4562 4563
  DBUG_EXECUTE("info",print_ror_scans_arr(param->table, "ordered",
                                          tree->ror_scans,
4564
                                          tree->ror_scans_end););
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4565

4566 4567 4568 4569 4570 4571 4572 4573 4574
  ROR_SCAN_INFO **intersect_scans; /* ROR scans used in index intersection */
  ROR_SCAN_INFO **intersect_scans_end;
  if (!(intersect_scans= (ROR_SCAN_INFO**)alloc_root(param->mem_root,
                                                     sizeof(ROR_SCAN_INFO*)*
                                                     tree->n_ror_scans)))
    return NULL;
  intersect_scans_end= intersect_scans;

  /* Create and incrementally update ROR intersection. */
4575 4576 4577
  ROR_INTERSECT_INFO *intersect, *intersect_best;
  if (!(intersect= ror_intersect_init(param)) || 
      !(intersect_best= ror_intersect_init(param)))
4578
    return NULL;
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4579

4580
  /* [intersect_scans,intersect_scans_best) will hold the best intersection */
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4581
  ROR_SCAN_INFO **intersect_scans_best;
4582
  cur_ror_scan= tree->ror_scans;
4583
  intersect_scans_best= intersect_scans;
4584
  while (cur_ror_scan != tree->ror_scans_end && !intersect->is_covering)
4585
  {
4586
    /* S= S + first(R);  R= R - first(R); */
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4587
    if (!ror_intersect_add(intersect, *cur_ror_scan, FALSE))
4588 4589 4590 4591 4592 4593
    {
      cur_ror_scan++;
      continue;
    }
    
    *(intersect_scans_end++)= *(cur_ror_scan++);
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4594

4595
    if (intersect->total_cost < min_cost)
4596
    {
4597
      /* Local minimum found, save it */
4598
      ror_intersect_cpy(intersect_best, intersect);
4599
      intersect_scans_best= intersect_scans_end;
4600
      min_cost = intersect->total_cost;
4601 4602
    }
  }
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4603

4604 4605 4606 4607 4608 4609
  if (intersect_scans_best == intersect_scans)
  {
    DBUG_PRINT("info", ("None of scans increase selectivity"));
    DBUG_RETURN(NULL);
  }
    
4610 4611 4612 4613
  DBUG_EXECUTE("info",print_ror_scans_arr(param->table,
                                          "best ROR-intersection",
                                          intersect_scans,
                                          intersect_scans_best););
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4614

4615
  *are_all_covering= intersect->is_covering;
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4616
  uint best_num= intersect_scans_best - intersect_scans;
4617 4618
  ror_intersect_cpy(intersect, intersect_best);

4619 4620
  /*
    Ok, found the best ROR-intersection of non-CPK key scans.
4621 4622
    Check if we should add a CPK scan. If the obtained ROR-intersection is 
    covering, it doesn't make sense to add CPK scan.
4623 4624
  */
  if (cpk_scan && !intersect->is_covering)
4625
  {
4626
    if (ror_intersect_add(intersect, cpk_scan, TRUE) && 
4627
        (intersect->total_cost < min_cost))
4628
    {
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4629
      cpk_scan_used= TRUE;
4630
      intersect_best= intersect; //just set pointer here
4631 4632
    }
  }
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4633

4634
  /* Ok, return ROR-intersect plan if we have found one */
4635
  TRP_ROR_INTERSECT *trp= NULL;
4636
  if (min_cost < read_time && (cpk_scan_used || best_num > 1))
4637
  {
4638 4639
    if (!(trp= new (param->mem_root) TRP_ROR_INTERSECT))
      DBUG_RETURN(trp);
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4640 4641
    if (!(trp->first_scan=
           (ROR_SCAN_INFO**)alloc_root(param->mem_root,
4642 4643 4644 4645
                                       sizeof(ROR_SCAN_INFO*)*best_num)))
      DBUG_RETURN(NULL);
    memcpy(trp->first_scan, intersect_scans, best_num*sizeof(ROR_SCAN_INFO*));
    trp->last_scan=  trp->first_scan + best_num;
4646 4647 4648 4649 4650 4651
    trp->is_covering= intersect_best->is_covering;
    trp->read_cost= intersect_best->total_cost;
    /* Prevent divisons by zero */
    ha_rows best_rows = double2rows(intersect_best->out_rows);
    if (!best_rows)
      best_rows= 1;
4652
    set_if_smaller(param->table->quick_condition_rows, best_rows);
4653
    trp->records= best_rows;
4654 4655 4656 4657 4658
    trp->index_scan_costs= intersect_best->index_scan_costs;
    trp->cpk_scan= cpk_scan_used? cpk_scan: NULL;
    DBUG_PRINT("info", ("Returning non-covering ROR-intersect plan:"
                        "cost %g, records %lu",
                        trp->read_cost, (ulong) trp->records));
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4659
  }
4660
  DBUG_RETURN(trp);
4661 4662 4663 4664
}


/*
4665
  Get best covering ROR-intersection.
4666
  SYNOPSIS
4667
    get_best_covering_ror_intersect()
4668 4669 4670
      param     Parameter from test_quick_select function.
      tree      SEL_TREE with sets of intervals for different keys.
      read_time Don't return table read plans with cost > read_time.
4671

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4672 4673
  RETURN
    Best covering ROR-intersection plan
4674
    NULL if no plan found.
4675 4676

  NOTES
4677
    get_best_ror_intersect must be called for a tree before calling this
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4678
    function for it.
4679
    This function invalidates tree->ror_scans member values.
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4680

4681 4682 4683 4684 4685
  The following approximate algorithm is used:
    I=set of all covering indexes
    F=set of all fields to cover
    S={}

4686 4687
    do
    {
4688 4689 4690 4691 4692 4693 4694
      Order I by (#covered fields in F desc,
                  #components asc,
                  number of first not covered component asc);
      F=F-covered by first(I);
      S=S+first(I);
      I=I-first(I);
    } while F is not empty.
4695 4696
*/

4697
static
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4698 4699
TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
                                                   SEL_TREE *tree,
4700
                                                   double read_time)
4701
{
4702
  ROR_SCAN_INFO **ror_scan_mark;
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4703
  ROR_SCAN_INFO **ror_scans_end= tree->ror_scans_end;
4704 4705
  DBUG_ENTER("get_best_covering_ror_intersect");

4706
  if (!optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_INTERSECT))
4707 4708
    DBUG_RETURN(NULL);

4709
  for (ROR_SCAN_INFO **scan= tree->ror_scans; scan != ror_scans_end; ++scan)
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4710
    (*scan)->key_components=
4711
      param->table->key_info[(*scan)->keynr].key_parts;
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4712

4713 4714
  /*
    Run covering-ROR-search algorithm.
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4715
    Assume set I is [ror_scan .. ror_scans_end)
4716
  */
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4717

4718 4719
  /*I=set of all covering indexes */
  ror_scan_mark= tree->ror_scans;
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4720

4721 4722
  MY_BITMAP *covered_fields= &param->tmp_covered_fields;
  if (!covered_fields->bitmap) 
4723
    covered_fields->bitmap= (my_bitmap_map*)alloc_root(param->mem_root,
4724 4725
                                               param->fields_bitmap_size);
  if (!covered_fields->bitmap ||
4726 4727
      bitmap_init(covered_fields, covered_fields->bitmap,
                  param->table->s->fields, FALSE))
4728
    DBUG_RETURN(0);
4729
  bitmap_clear_all(covered_fields);
4730 4731 4732

  double total_cost= 0.0f;
  ha_rows records=0;
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4733 4734
  bool all_covered;

4735 4736 4737 4738
  DBUG_PRINT("info", ("Building covering ROR-intersection"));
  DBUG_EXECUTE("info", print_ror_scans_arr(param->table,
                                           "building covering ROR-I",
                                           ror_scan_mark, ror_scans_end););
4739 4740
  do
  {
4741
    /*
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4742
      Update changed sorting info:
4743
        #covered fields,
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4744
	number of first not covered component
4745 4746 4747 4748
      Calculate and save these values for each of remaining scans.
    */
    for (ROR_SCAN_INFO **scan= ror_scan_mark; scan != ror_scans_end; ++scan)
    {
4749
      bitmap_subtract(&(*scan)->covered_fields, covered_fields);
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      (*scan)->used_fields_covered=
4751
        bitmap_bits_set(&(*scan)->covered_fields);
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      (*scan)->first_uncovered_field=
4753 4754 4755
        bitmap_get_first(&(*scan)->covered_fields);
    }

4756 4757
    my_qsort(ror_scan_mark, ror_scans_end-ror_scan_mark, sizeof(ROR_SCAN_INFO*),
             (qsort_cmp)cmp_ror_scan_info_covering);
4758 4759 4760 4761

    DBUG_EXECUTE("info", print_ror_scans_arr(param->table,
                                             "remaining scans",
                                             ror_scan_mark, ror_scans_end););
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4763 4764 4765
    /* I=I-first(I) */
    total_cost += (*ror_scan_mark)->index_read_cost;
    records += (*ror_scan_mark)->records;
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    DBUG_PRINT("info", ("Adding scan on %s",
4767 4768 4769 4770
                        param->table->key_info[(*ror_scan_mark)->keynr].name));
    if (total_cost > read_time)
      DBUG_RETURN(NULL);
    /* F=F-covered by first(I) */
4771 4772
    bitmap_union(covered_fields, &(*ror_scan_mark)->covered_fields);
    all_covered= bitmap_is_subset(&param->needed_fields, covered_fields);
4773 4774 4775 4776
  } while ((++ror_scan_mark < ror_scans_end) && !all_covered);
  
  if (!all_covered || (ror_scan_mark - tree->ror_scans) == 1)
    DBUG_RETURN(NULL);
4777 4778 4779 4780 4781 4782 4783 4784 4785

  /*
    Ok, [tree->ror_scans .. ror_scan) holds covering index_intersection with
    cost total_cost.
  */
  DBUG_PRINT("info", ("Covering ROR-intersect scans cost: %g", total_cost));
  DBUG_EXECUTE("info", print_ror_scans_arr(param->table,
                                           "creating covering ROR-intersect",
                                           tree->ror_scans, ror_scan_mark););
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4787
  /* Add priority queue use cost. */
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  total_cost += rows2double(records)*
                log((double)(ror_scan_mark - tree->ror_scans)) /
4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 4800 4801 4802 4803
                (TIME_FOR_COMPARE_ROWID * M_LN2);
  DBUG_PRINT("info", ("Covering ROR-intersect full cost: %g", total_cost));

  if (total_cost > read_time)
    DBUG_RETURN(NULL);

  TRP_ROR_INTERSECT *trp;
  if (!(trp= new (param->mem_root) TRP_ROR_INTERSECT))
    DBUG_RETURN(trp);
  uint best_num= (ror_scan_mark - tree->ror_scans);
  if (!(trp->first_scan= (ROR_SCAN_INFO**)alloc_root(param->mem_root,
                                                     sizeof(ROR_SCAN_INFO*)*
                                                     best_num)))
    DBUG_RETURN(NULL);
4804
  memcpy(trp->first_scan, tree->ror_scans, best_num*sizeof(ROR_SCAN_INFO*));
4805
  trp->last_scan=  trp->first_scan + best_num;
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  trp->is_covering= TRUE;
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  trp->read_cost= total_cost;
  trp->records= records;
4809
  trp->cpk_scan= NULL;
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  set_if_smaller(param->table->quick_condition_rows, records); 
4811

4812 4813 4814
  DBUG_PRINT("info",
             ("Returning covering ROR-intersect plan: cost %g, records %lu",
              trp->read_cost, (ulong) trp->records));
4815
  DBUG_RETURN(trp);
4816 4817 4818
}


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/*
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  Get best "range" table read plan for given SEL_TREE.
4821
  Also update PARAM members and store ROR scans info in the SEL_TREE.
4822
  SYNOPSIS
4823
    get_key_scans_params
4824
      param        parameters from test_quick_select
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      tree         make range select for this SEL_TREE
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      index_read_must_be_used if TRUE, assume 'index only' option will be set
4827
                             (except for clustered PK indexes)
4828 4829
      read_time    don't create read plans with cost > read_time.
  RETURN
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    Best range read plan
4831
    NULL if no plan found or error occurred
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*/

4834
static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
4835 4836
                                       bool index_read_must_be_used, 
                                       bool update_tbl_stats,
4837
                                       double read_time)
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{
  int idx;
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  SEL_ARG **key,**end, **key_to_read= NULL;
  ha_rows best_records;
  TRP_RANGE* read_plan= NULL;
4843
  bool pk_is_clustered= param->table->file->primary_key_is_clustered();
4844 4845
  DBUG_ENTER("get_key_scans_params");
  LINT_INIT(best_records); /* protected by key_to_read */
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  /*
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    Note that there may be trees that have type SEL_TREE::KEY but contain no
    key reads at all, e.g. tree for expression "key1 is not null" where key1
4849
    is defined as "not null".
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  */
  DBUG_EXECUTE("info", print_sel_tree(param, tree, &tree->keys_map,
4852 4853 4854 4855
                                      "tree scans"););
  tree->ror_scans_map.clear_all();
  tree->n_ror_scans= 0;
  for (idx= 0,key=tree->keys, end=key+param->keys;
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       key != end ;
       key++,idx++)
  {
    ha_rows found_records;
    double found_read_time;
    if (*key)
    {
4863
      uint keynr= param->real_keynr[idx];
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      if ((*key)->type == SEL_ARG::MAYBE_KEY ||
          (*key)->maybe_flag)
4866
        param->needed_reg->set_bit(keynr);
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4867

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      bool read_index_only= index_read_must_be_used ? TRUE :
4869
                            (bool) param->table->covering_keys.is_set(keynr);
4870

4871
      found_records= check_quick_select(param, idx, *key, update_tbl_stats);
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      if (param->is_ror_scan)
      {
        tree->n_ror_scans++;
        tree->ror_scans_map.set_bit(idx);
      }
4877
      double cpu_cost= (double) found_records / TIME_FOR_COMPARE;
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      if (found_records != HA_POS_ERROR && found_records > 2 &&
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          read_index_only &&
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          (param->table->file->index_flags(keynr, param->max_key_part,1) &
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           HA_KEYREAD_ONLY) &&
4882
          !(pk_is_clustered && keynr == param->table->s->primary_key))
4883 4884 4885 4886 4887
      {
        /*
          We can resolve this by only reading through this key. 
          0.01 is added to avoid races between range and 'index' scan.
        */
4888
        found_read_time= get_index_only_read_time(param,found_records,keynr) +
4889 4890
                         cpu_cost + 0.01;
      }
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      else
4892
      {
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        /*
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          cost(read_through_index) = cost(disk_io) + cost(row_in_range_checks)
          The row_in_range check is in QUICK_RANGE_SELECT::cmp_next function.
        */
4897 4898 4899
	found_read_time= param->table->file->read_time(keynr,
                                                       param->range_count,
                                                       found_records) +
4900 4901
			 cpu_cost + 0.01;
      }
4902 4903 4904
      DBUG_PRINT("info",("key %s: found_read_time: %g (cur. read_time: %g)",
                         param->table->key_info[keynr].name, found_read_time,
                         read_time));
4905

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4906
      if (read_time > found_read_time && found_records != HA_POS_ERROR)
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      {
4908
        read_time=    found_read_time;
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        best_records= found_records;
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        key_to_read=  key;
      }

    }
  }

  DBUG_EXECUTE("info", print_sel_tree(param, tree, &tree->ror_scans_map,
                                      "ROR scans"););
  if (key_to_read)
  {
    idx= key_to_read - tree->keys;
    if ((read_plan= new (param->mem_root) TRP_RANGE(*key_to_read, idx)))
    {
      read_plan->records= best_records;
      read_plan->is_ror= tree->ror_scans_map.is_set(idx);
      read_plan->read_cost= read_time;
4926 4927 4928 4929
      DBUG_PRINT("info",
                 ("Returning range plan for key %s, cost %g, records %lu",
                  param->table->key_info[param->real_keynr[idx]].name,
                  read_plan->read_cost, (ulong) read_plan->records));
4930 4931 4932 4933 4934 4935 4936 4937 4938
    }
  }
  else
    DBUG_PRINT("info", ("No 'range' table read plan found"));

  DBUG_RETURN(read_plan);
}


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4939
QUICK_SELECT_I *TRP_INDEX_MERGE::make_quick(PARAM *param,
4940 4941 4942 4943 4944 4945 4946 4947 4948 4949 4950
                                            bool retrieve_full_rows,
                                            MEM_ROOT *parent_alloc)
{
  QUICK_INDEX_MERGE_SELECT *quick_imerge;
  QUICK_RANGE_SELECT *quick;
  /* index_merge always retrieves full rows, ignore retrieve_full_rows */
  if (!(quick_imerge= new QUICK_INDEX_MERGE_SELECT(param->thd, param->table)))
    return NULL;

  quick_imerge->records= records;
  quick_imerge->read_time= read_cost;
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  for (TRP_RANGE **range_scan= range_scans; range_scan != range_scans_end;
       range_scan++)
4953 4954
  {
    if (!(quick= (QUICK_RANGE_SELECT*)
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          ((*range_scan)->make_quick(param, FALSE, &quick_imerge->alloc)))||
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        quick_imerge->push_quick_back(quick))
    {
      delete quick;
      delete quick_imerge;
      return NULL;
    }
  }
  return quick_imerge;
}

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QUICK_SELECT_I *TRP_ROR_INTERSECT::make_quick(PARAM *param,
4967 4968 4969 4970 4971 4972 4973
                                              bool retrieve_full_rows,
                                              MEM_ROOT *parent_alloc)
{
  QUICK_ROR_INTERSECT_SELECT *quick_intrsect;
  QUICK_RANGE_SELECT *quick;
  DBUG_ENTER("TRP_ROR_INTERSECT::make_quick");
  MEM_ROOT *alloc;
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4974 4975

  if ((quick_intrsect=
4976
         new QUICK_ROR_INTERSECT_SELECT(param->thd, param->table,
4977 4978
                                        (retrieve_full_rows? (!is_covering) :
                                         FALSE),
4979 4980
                                        parent_alloc)))
  {
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    DBUG_EXECUTE("info", print_ror_scans_arr(param->table,
4982 4983 4984
                                             "creating ROR-intersect",
                                             first_scan, last_scan););
    alloc= parent_alloc? parent_alloc: &quick_intrsect->alloc;
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    for (; first_scan != last_scan;++first_scan)
4986 4987 4988 4989
    {
      if (!(quick= get_quick_select(param, (*first_scan)->idx,
                                    (*first_scan)->sel_arg, alloc)) ||
          quick_intrsect->push_quick_back(quick))
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      {
4991 4992
        delete quick_intrsect;
        DBUG_RETURN(NULL);
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      }
    }
4995 4996 4997 4998
    if (cpk_scan)
    {
      if (!(quick= get_quick_select(param, cpk_scan->idx,
                                    cpk_scan->sel_arg, alloc)))
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      {
5000 5001
        delete quick_intrsect;
        DBUG_RETURN(NULL);
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      }
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      quick->file= NULL; 
5004
      quick_intrsect->cpk_quick= quick;
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    }
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    quick_intrsect->records= records;
5007
    quick_intrsect->read_time= read_cost;
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  }
5009 5010 5011
  DBUG_RETURN(quick_intrsect);
}

5012

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5013
QUICK_SELECT_I *TRP_ROR_UNION::make_quick(PARAM *param,
5014 5015 5016 5017 5018 5019 5020
                                          bool retrieve_full_rows,
                                          MEM_ROOT *parent_alloc)
{
  QUICK_ROR_UNION_SELECT *quick_roru;
  TABLE_READ_PLAN **scan;
  QUICK_SELECT_I *quick;
  DBUG_ENTER("TRP_ROR_UNION::make_quick");
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5021 5022
  /*
    It is impossible to construct a ROR-union that will not retrieve full
5023
    rows, ignore retrieve_full_rows parameter.
5024 5025 5026
  */
  if ((quick_roru= new QUICK_ROR_UNION_SELECT(param->thd, param->table)))
  {
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    for (scan= first_ror; scan != last_ror; scan++)
5028
    {
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5029
      if (!(quick= (*scan)->make_quick(param, FALSE, &quick_roru->alloc)) ||
5030 5031 5032 5033 5034
          quick_roru->push_quick_back(quick))
        DBUG_RETURN(NULL);
    }
    quick_roru->records= records;
    quick_roru->read_time= read_cost;
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5035
  }
5036
  DBUG_RETURN(quick_roru);
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5037 5038
}

5039

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5040
/*
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5041
  Build a SEL_TREE for <> or NOT BETWEEN predicate
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5042 5043 5044 5045 5046 5047
 
  SYNOPSIS
    get_ne_mm_tree()
      param       PARAM from SQL_SELECT::test_quick_select
      cond_func   item for the predicate
      field       field in the predicate
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5048 5049
      lt_value    constant that field should be smaller
      gt_value    constant that field should be greaterr
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      cmp_type    compare type for the field

  RETURN 
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5053 5054
    #  Pointer to tree built tree
    0  on error
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5055 5056
*/

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5057
static SEL_TREE *get_ne_mm_tree(RANGE_OPT_PARAM *param, Item_func *cond_func, 
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5058 5059
                                Field *field,
                                Item *lt_value, Item *gt_value,
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5060 5061
                                Item_result cmp_type)
{
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  SEL_TREE *tree;
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  tree= get_mm_parts(param, cond_func, field, Item_func::LT_FUNC,
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5064
                     lt_value, cmp_type);
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5065 5066 5067 5068
  if (tree)
  {
    tree= tree_or(param, tree, get_mm_parts(param, cond_func, field,
					    Item_func::GT_FUNC,
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5069
					    gt_value, cmp_type));
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  }
  return tree;
}
   

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5075 5076 5077 5078 5079 5080 5081 5082 5083 5084
/*
  Build a SEL_TREE for a simple predicate
 
  SYNOPSIS
    get_func_mm_tree()
      param       PARAM from SQL_SELECT::test_quick_select
      cond_func   item for the predicate
      field       field in the predicate
      value       constant in the predicate
      cmp_type    compare type for the field
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      inv         TRUE <> NOT cond_func is considered
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                  (makes sense only when cond_func is BETWEEN or IN) 
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5087 5088

  RETURN 
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    Pointer to the tree built tree
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5090 5091
*/

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static SEL_TREE *get_func_mm_tree(RANGE_OPT_PARAM *param, Item_func *cond_func, 
5093
                                  Field *field, Item *value,
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5094
                                  Item_result cmp_type, bool inv)
5095 5096 5097 5098
{
  SEL_TREE *tree= 0;
  DBUG_ENTER("get_func_mm_tree");

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  switch (cond_func->functype()) {
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5100

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  case Item_func::NE_FUNC:
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    tree= get_ne_mm_tree(param, cond_func, field, value, value, cmp_type);
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    break;
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5104

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  case Item_func::BETWEEN:
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  {
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    if (!value)
5108
    {
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5109
      if (inv)
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      {
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5111 5112 5113 5114
        tree= get_ne_mm_tree(param, cond_func, field, cond_func->arguments()[1],
                             cond_func->arguments()[2], cmp_type);
      }
      else
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      {
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        tree= get_mm_parts(param, cond_func, field, Item_func::GE_FUNC,
		           cond_func->arguments()[1],cmp_type);
        if (tree)
        {
          tree= tree_and(param, tree, get_mm_parts(param, cond_func, field,
					           Item_func::LE_FUNC,
					           cond_func->arguments()[2],
                                                   cmp_type));
        }
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      }
5126
    }
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    else
      tree= get_mm_parts(param, cond_func, field,
                         (inv ?
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5130 5131 5132 5133
                          (value == (Item*)1 ? Item_func::GT_FUNC :
                                               Item_func::LT_FUNC):
                          (value == (Item*)1 ? Item_func::LE_FUNC :
                                               Item_func::GE_FUNC)),
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                         cond_func->arguments()[0], cmp_type);
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    break;
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  }
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  case Item_func::IN_FUNC:
5138 5139
  {
    Item_func_in *func=(Item_func_in*) cond_func;
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5140

5141 5142 5143 5144 5145
    /*
      Array for IN() is constructed when all values have the same result
      type. Tree won't be built for values with different result types,
      so we check it here to avoid unnecessary work.
    */
5146 5147
    if (!func->arg_types_compatible)
      break;     
5148

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5149
    if (inv)
5150
    {
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5151
      if (func->array && func->array->result_type() != ROW_RESULT)
5152
      {
5153
        /*
5154 5155 5156
          We get here for conditions in form "t.key NOT IN (c1, c2, ...)",
          where c{i} are constants. Our goal is to produce a SEL_TREE that 
          represents intervals:
5157 5158 5159 5160 5161
          
          ($MIN<t.key<c1) OR (c1<t.key<c2) OR (c2<t.key<c3) OR ...    (*)
          
          where $MIN is either "-inf" or NULL.
          
5162 5163 5164 5165 5166 5167 5168 5169 5170 5171 5172 5173 5174 5175 5176 5177 5178
          The most straightforward way to produce it is to convert NOT IN
          into "(t.key != c1) AND (t.key != c2) AND ... " and let the range
          analyzer to build SEL_TREE from that. The problem is that the
          range analyzer will use O(N^2) memory (which is probably a bug),
          and people do use big NOT IN lists (e.g. see BUG#15872, BUG#21282),
          will run out of memory.

          Another problem with big lists like (*) is that a big list is
          unlikely to produce a good "range" access, while considering that
          range access will require expensive CPU calculations (and for 
          MyISAM even index accesses). In short, big NOT IN lists are rarely
          worth analyzing.

          Considering the above, we'll handle NOT IN as follows:
          * if the number of entries in the NOT IN list is less than
            NOT_IN_IGNORE_THRESHOLD, construct the SEL_TREE (*) manually.
          * Otherwise, don't produce a SEL_TREE.
5179
        */
5180
#define NOT_IN_IGNORE_THRESHOLD 1000
5181 5182
        MEM_ROOT *tmp_root= param->mem_root;
        param->thd->mem_root= param->old_root;
5183 5184 5185 5186 5187 5188 5189 5190 5191 5192 5193
        /* 
          Create one Item_type constant object. We'll need it as
          get_mm_parts only accepts constant values wrapped in Item_Type
          objects.
          We create the Item on param->mem_root which points to
          per-statement mem_root (while thd->mem_root is currently pointing
          to mem_root local to range optimizer).
        */
        Item *value_item= func->array->create_item();
        param->thd->mem_root= tmp_root;

5194
        if (func->array->count > NOT_IN_IGNORE_THRESHOLD || !value_item)
5195
          break;
5196

5197
        /* Get a SEL_TREE for "(-inf|NULL) < X < c_0" interval.  */
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        uint i=0;
        do 
        {
          func->array->value_to_item(i, value_item);
          tree= get_mm_parts(param, cond_func, field, Item_func::LT_FUNC,
                             value_item, cmp_type);
          if (!tree)
            break;
          i++;
        } while (i < func->array->count && tree->type == SEL_TREE::IMPOSSIBLE);

        if (!tree || tree->type == SEL_TREE::IMPOSSIBLE)
        {
          /* We get here in cases like "t.unsigned NOT IN (-1,-2,-3) */
          tree= NULL;
5213
          break;
5214
        }
5215
        SEL_TREE *tree2;
5216
        for (; i < func->array->count; i++)
5217
        {
5218
          if (func->array->compare_elems(i, i-1))
5219
          {
5220 5221 5222 5223 5224
            /* Get a SEL_TREE for "-inf < X < c_i" interval */
            func->array->value_to_item(i, value_item);
            tree2= get_mm_parts(param, cond_func, field, Item_func::LT_FUNC,
                                value_item, cmp_type);
            if (!tree2)
5225
            {
5226 5227 5228
              tree= NULL;
              break;
            }
5229

5230 5231 5232 5233
            /* Change all intervals to be "c_{i-1} < X < c_i" */
            for (uint idx= 0; idx < param->keys; idx++)
            {
              SEL_ARG *new_interval, *last_val;
5234 5235
              if (((new_interval= tree2->keys[idx])) &&
                  (tree->keys[idx]) &&
5236
                  ((last_val= tree->keys[idx]->last())))
5237
              {
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                new_interval->min_value= last_val->max_value;
                new_interval->min_flag= NEAR_MIN;
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              }
            }
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            /* 
              The following doesn't try to allocate memory so no need to
              check for NULL.
            */
            tree= tree_or(param, tree, tree2);
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          }
        }
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        if (tree && tree->type != SEL_TREE::IMPOSSIBLE)
        {
          /* 
            Get the SEL_TREE for the last "c_last < X < +inf" interval 
            (value_item cotains c_last already)
          */
          tree2= get_mm_parts(param, cond_func, field, Item_func::GT_FUNC,
                              value_item, cmp_type);
          tree= tree_or(param, tree, tree2);
        }
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      }
      else
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      {
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        tree= get_ne_mm_tree(param, cond_func, field,
                             func->arguments()[1], func->arguments()[1],
                             cmp_type);
        if (tree)
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        {
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          Item **arg, **end;
          for (arg= func->arguments()+2, end= arg+func->argument_count()-2;
               arg < end ; arg++)
          {
            tree=  tree_and(param, tree, get_ne_mm_tree(param, cond_func, field, 
                                                        *arg, *arg, cmp_type));
          }
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        }
      }
    }
    else
    {    
      tree= get_mm_parts(param, cond_func, field, Item_func::EQ_FUNC,
                         func->arguments()[1], cmp_type);
      if (tree)
      {
        Item **arg, **end;
        for (arg= func->arguments()+2, end= arg+func->argument_count()-2;
             arg < end ; arg++)
        {
          tree= tree_or(param, tree, get_mm_parts(param, cond_func, field, 
                                                  Item_func::EQ_FUNC,
                                                  *arg, cmp_type));
        }
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      }
    }
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    break;
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  }
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  default: 
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  {
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    /* 
       Here the function for the following predicates are processed:
       <, <=, =, >=, >, LIKE, IS NULL, IS NOT NULL.
       If the predicate is of the form (value op field) it is handled
       as the equivalent predicate (field rev_op value), e.g.
       2 <= a is handled as a >= 2.
    */
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    Item_func::Functype func_type=
      (value != cond_func->arguments()[0]) ? cond_func->functype() :
        ((Item_bool_func2*) cond_func)->rev_functype();
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    tree= get_mm_parts(param, cond_func, field, func_type, value, cmp_type);
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  }
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  }

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  DBUG_RETURN(tree);
}
5314

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/*
  Build conjunction of all SEL_TREEs for a simple predicate applying equalities
 
  SYNOPSIS
    get_full_func_mm_tree()
      param       PARAM from SQL_SELECT::test_quick_select
      cond_func   item for the predicate
      field_item  field in the predicate
      value       constant in the predicate
                  (for BETWEEN it contains the number of the field argument,
                   for IN it's always 0) 
      inv         TRUE <> NOT cond_func is considered
                  (makes sense only when cond_func is BETWEEN or IN)

  DESCRIPTION
    For a simple SARGable predicate of the form (f op c), where f is a field and
    c is a constant, the function builds a conjunction of all SEL_TREES that can
    be obtained by the substitution of f for all different fields equal to f.

  NOTES  
    If the WHERE condition contains a predicate (fi op c),
    then not only SELL_TREE for this predicate is built, but
    the trees for the results of substitution of fi for
    each fj belonging to the same multiple equality as fi
    are built as well.
    E.g. for WHERE t1.a=t2.a AND t2.a > 10 
    a SEL_TREE for t2.a > 10 will be built for quick select from t2
    and   
    a SEL_TREE for t1.a > 10 will be built for quick select from t1.

    A BETWEEN predicate of the form (fi [NOT] BETWEEN c1 AND c2) is treated
    in a similar way: we build a conjuction of trees for the results
    of all substitutions of fi for equal fj.
    Yet a predicate of the form (c BETWEEN f1i AND f2i) is processed
    differently. It is considered as a conjuction of two SARGable
    predicates (f1i <= c) and (f2i <=c) and the function get_full_func_mm_tree
    is called for each of them separately producing trees for 
       AND j (f1j <=c ) and AND j (f2j <= c) 
    After this these two trees are united in one conjunctive tree.
    It's easy to see that the same tree is obtained for
       AND j,k (f1j <=c AND f2k<=c)
    which is equivalent to 
       AND j,k (c BETWEEN f1j AND f2k).
    The validity of the processing of the predicate (c NOT BETWEEN f1i AND f2i)
    which equivalent to (f1i > c OR f2i < c) is not so obvious. Here the
    function get_full_func_mm_tree is called for (f1i > c) and (f2i < c)
    producing trees for AND j (f1j > c) and AND j (f2j < c). Then this two
    trees are united in one OR-tree. The expression 
      (AND j (f1j > c) OR AND j (f2j < c)
    is equivalent to the expression
      AND j,k (f1j > c OR f2k < c) 
    which is just a translation of 
      AND j,k (c NOT BETWEEN f1j AND f2k)

    In the cases when one of the items f1, f2 is a constant c1 we do not create
    a tree for it at all. It works for BETWEEN predicates but does not
    work for NOT BETWEEN predicates as we have to evaluate the expression
    with it. If it is TRUE then the other tree can be completely ignored.
    We do not do it now and no trees are built in these cases for
    NOT BETWEEN predicates.

    As to IN predicates only ones of the form (f IN (c1,...,cn)),
    where f1 is a field and c1,...,cn are constant, are considered as
    SARGable. We never try to narrow the index scan using predicates of
    the form (c IN (c1,...,f,...,cn)). 
      
  RETURN 
    Pointer to the tree representing the built conjunction of SEL_TREEs
*/

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static SEL_TREE *get_full_func_mm_tree(RANGE_OPT_PARAM *param,
                                       Item_func *cond_func,
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                                       Item_field *field_item, Item *value, 
                                       bool inv)
{
  SEL_TREE *tree= 0;
  SEL_TREE *ftree= 0;
  table_map ref_tables= 0;
  table_map param_comp= ~(param->prev_tables | param->read_tables |
		          param->current_table);
  DBUG_ENTER("get_full_func_mm_tree");

  for (uint i= 0; i < cond_func->arg_count; i++)
  {
    Item *arg= cond_func->arguments()[i]->real_item();
    if (arg != field_item)
      ref_tables|= arg->used_tables();
  }
  Field *field= field_item->field;
  Item_result cmp_type= field->cmp_type();
  if (!((ref_tables | field->table->map) & param_comp))
    ftree= get_func_mm_tree(param, cond_func, field, value, cmp_type, inv);
  Item_equal *item_equal= field_item->item_equal;
  if (item_equal)
  {
    Item_equal_iterator it(*item_equal);
    Item_field *item;
    while ((item= it++))
    {
      Field *f= item->field;
      if (field->eq(f))
        continue;
      if (!((ref_tables | f->table->map) & param_comp))
      {
        tree= get_func_mm_tree(param, cond_func, f, value, cmp_type, inv);
        ftree= !ftree ? tree : tree_and(param, ftree, tree);
      }
    }
  }
  DBUG_RETURN(ftree);
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}

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	/* make a select tree of all keys in condition */

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static SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param,COND *cond)
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{
  SEL_TREE *tree=0;
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  SEL_TREE *ftree= 0;
  Item_field *field_item= 0;
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  bool inv= FALSE;
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  Item *value= 0;
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  DBUG_ENTER("get_mm_tree");

  if (cond->type() == Item::COND_ITEM)
  {
    List_iterator<Item> li(*((Item_cond*) cond)->argument_list());

    if (((Item_cond*) cond)->functype() == Item_func::COND_AND_FUNC)
    {
      tree=0;
      Item *item;
      while ((item=li++))
      {
	SEL_TREE *new_tree=get_mm_tree(param,item);
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	if (param->thd->is_fatal_error || 
            param->alloced_sel_args > SEL_ARG::MAX_SEL_ARGS)
5452
	  DBUG_RETURN(0);	// out of memory
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	tree=tree_and(param,tree,new_tree);
	if (tree && tree->type == SEL_TREE::IMPOSSIBLE)
	  break;
      }
    }
    else
    {						// COND OR
      tree=get_mm_tree(param,li++);
      if (tree)
      {
	Item *item;
	while ((item=li++))
	{
	  SEL_TREE *new_tree=get_mm_tree(param,item);
	  if (!new_tree)
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	    DBUG_RETURN(0);	// out of memory
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	  tree=tree_or(param,tree,new_tree);
	  if (!tree || tree->type == SEL_TREE::ALWAYS)
	    break;
	}
      }
    }
    DBUG_RETURN(tree);
  }
  /* Here when simple cond */
  if (cond->const_item())
  {
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    /*
      During the cond->val_int() evaluation we can come across a subselect 
      item which may allocate memory on the thd->mem_root and assumes 
      all the memory allocated has the same life span as the subselect 
      item itself. So we have to restore the thread's mem_root here.
    */
    MEM_ROOT *tmp_root= param->mem_root;
    param->thd->mem_root= param->old_root;
    tree= cond->val_int() ? new(tmp_root) SEL_TREE(SEL_TREE::ALWAYS) :
                            new(tmp_root) SEL_TREE(SEL_TREE::IMPOSSIBLE);
    param->thd->mem_root= tmp_root;
    DBUG_RETURN(tree);
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  }
5493

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  table_map ref_tables= 0;
  table_map param_comp= ~(param->prev_tables | param->read_tables |
		          param->current_table);
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  if (cond->type() != Item::FUNC_ITEM)
  {						// Should be a field
5499
    ref_tables= cond->used_tables();
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    if ((ref_tables & param->current_table) ||
	(ref_tables & ~(param->prev_tables | param->read_tables)))
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      DBUG_RETURN(0);
    DBUG_RETURN(new SEL_TREE(SEL_TREE::MAYBE));
  }
5505

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  Item_func *cond_func= (Item_func*) cond;
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  if (cond_func->functype() == Item_func::BETWEEN ||
      cond_func->functype() == Item_func::IN_FUNC)
    inv= ((Item_func_opt_neg *) cond_func)->negated;
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  else if (cond_func->select_optimize() == Item_func::OPTIMIZE_NONE)
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    DBUG_RETURN(0);			       
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  param->cond= cond;

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  switch (cond_func->functype()) {
  case Item_func::BETWEEN:
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    if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM)
    {
      field_item= (Item_field*) (cond_func->arguments()[0]->real_item());
      ftree= get_full_func_mm_tree(param, cond_func, field_item, NULL, inv);
    }

    /*
      Concerning the code below see the NOTES section in
      the comments for the function get_full_func_mm_tree()
    */
    for (uint i= 1 ; i < cond_func->arg_count ; i++)
    {
      if (cond_func->arguments()[i]->real_item()->type() == Item::FIELD_ITEM)
      {
        field_item= (Item_field*) (cond_func->arguments()[i]->real_item());
        SEL_TREE *tmp= get_full_func_mm_tree(param, cond_func, 
5533
                                    field_item, (Item*)(intptr)i, inv);
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        if (inv)
          tree= !tree ? tmp : tree_or(param, tree, tmp);
        else 
          tree= tree_and(param, tree, tmp);
      }
      else if (inv)
      { 
        tree= 0;
        break;
      }
    }

    ftree = tree_and(param, ftree, tree);
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    break;
  case Item_func::IN_FUNC:
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  {
    Item_func_in *func=(Item_func_in*) cond_func;
5551
    if (func->key_item()->real_item()->type() != Item::FIELD_ITEM)
5552
      DBUG_RETURN(0);
5553
    field_item= (Item_field*) (func->key_item()->real_item());
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    ftree= get_full_func_mm_tree(param, cond_func, field_item, NULL, inv);
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    break;
5556
  }
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  case Item_func::MULT_EQUAL_FUNC:
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  {
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    Item_equal *item_equal= (Item_equal *) cond;    
    if (!(value= item_equal->get_const()))
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      DBUG_RETURN(0);
    Item_equal_iterator it(*item_equal);
    ref_tables= value->used_tables();
    while ((field_item= it++))
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    {
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      Field *field= field_item->field;
      Item_result cmp_type= field->cmp_type();
      if (!((ref_tables | field->table->map) & param_comp))
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      {
5570
        tree= get_mm_parts(param, cond, field, Item_func::EQ_FUNC,
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		           value,cmp_type);
        ftree= !ftree ? tree : tree_and(param, ftree, tree);
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      }
    }
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5576
    DBUG_RETURN(ftree);
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  }
  default:
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    if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM)
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    {
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      field_item= (Item_field*) (cond_func->arguments()[0]->real_item());
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      value= cond_func->arg_count > 1 ? cond_func->arguments()[1] : 0;
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    }
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    else if (cond_func->have_rev_func() &&
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             cond_func->arguments()[1]->real_item()->type() ==
                                                            Item::FIELD_ITEM)
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    {
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      field_item= (Item_field*) (cond_func->arguments()[1]->real_item());
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      value= cond_func->arguments()[0];
    }
    else
      DBUG_RETURN(0);
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    ftree= get_full_func_mm_tree(param, cond_func, field_item, value, inv);
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  }
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  DBUG_RETURN(ftree);
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}


static SEL_TREE *
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get_mm_parts(RANGE_OPT_PARAM *param, COND *cond_func, Field *field,
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	     Item_func::Functype type,
5603
	     Item *value, Item_result cmp_type)
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{
  DBUG_ENTER("get_mm_parts");
  if (field->table != param->table)
    DBUG_RETURN(0);

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  KEY_PART *key_part = param->key_parts;
  KEY_PART *end = param->key_parts_end;
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  SEL_TREE *tree=0;
  if (value &&
      value->used_tables() & ~(param->prev_tables | param->read_tables))
    DBUG_RETURN(0);
5615
  for (; key_part != end ; key_part++)
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  {
    if (field->eq(key_part->field))
    {
      SEL_ARG *sel_arg=0;
5620
      if (!tree && !(tree=new SEL_TREE()))
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	DBUG_RETURN(0);				// OOM
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      if (!value || !(value->used_tables() & ~param->read_tables))
      {
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	sel_arg=get_mm_leaf(param,cond_func,
			    key_part->field,key_part,type,value);
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	if (!sel_arg)
	  continue;
	if (sel_arg->type == SEL_ARG::IMPOSSIBLE)
	{
	  tree->type=SEL_TREE::IMPOSSIBLE;
	  DBUG_RETURN(tree);
	}
      }
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      else
      {
5636
	// This key may be used later
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	if (!(sel_arg= new SEL_ARG(SEL_ARG::MAYBE_KEY)))
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	  DBUG_RETURN(0);			// OOM
5639
      }
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      sel_arg->part=(uchar) key_part->part;
      tree->keys[key_part->key]=sel_add(tree->keys[key_part->key],sel_arg);
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      tree->keys_map.set_bit(key_part->key);
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    }
  }
5645

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  if (tree && tree->merges.is_empty() && tree->keys_map.is_clear_all())
    tree= NULL;
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  DBUG_RETURN(tree);
}


static SEL_ARG *
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get_mm_leaf(RANGE_OPT_PARAM *param, COND *conf_func, Field *field,
            KEY_PART *key_part, Item_func::Functype type,Item *value)
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{
5656
  uint maybe_null=(uint) field->real_maybe_null();
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  bool optimize_range;
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  SEL_ARG *tree= 0;
  MEM_ROOT *alloc= param->mem_root;
5660
  uchar *str;
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  ulong orig_sql_mode;
5662
  int err;
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  DBUG_ENTER("get_mm_leaf");

5665 5666
  /*
    We need to restore the runtime mem_root of the thread in this
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    function because it evaluates the value of its argument, while
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    the argument can be any, e.g. a subselect. The subselect
    items, in turn, assume that all the memory allocated during
    the evaluation has the same life span as the item itself.
    TODO: opt_range.cc should not reset thd->mem_root at all.
  */
  param->thd->mem_root= param->old_root;
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  if (!value)					// IS NULL or IS NOT NULL
  {
5676
    if (field->table->maybe_null)		// Can't use a key on this
5677
      goto end;
5678
    if (!maybe_null)				// Not null field
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    {
      if (type == Item_func::ISNULL_FUNC)
        tree= &null_element;
      goto end;
    }
    if (!(tree= new (alloc) SEL_ARG(field,is_null_string,is_null_string)))
      goto end;                                 // out of memory
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    if (type == Item_func::ISNOTNULL_FUNC)
    {
      tree->min_flag=NEAR_MIN;		    /* IS NOT NULL ->  X > NULL */
      tree->max_flag=NO_MAX_RANGE;
    }
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    goto end;
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  }

  /*
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    1. Usually we can't use an index if the column collation
       differ from the operation collation.

    2. However, we can reuse a case insensitive index for
       the binary searches:

       WHERE latin1_swedish_ci_column = 'a' COLLATE lati1_bin;

       WHERE latin1_swedish_ci_colimn = BINARY 'a '

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  */
  if (field->result_type() == STRING_RESULT &&
      value->result_type() == STRING_RESULT &&
      key_part->image_type == Field::itRAW &&
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      ((Field_str*)field)->charset() != conf_func->compare_collation() &&
      !(conf_func->compare_collation()->state & MY_CS_BINSORT))
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    goto end;
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  if (param->using_real_indexes)
    optimize_range= field->optimize_range(param->real_keynr[key_part->key],
                                          key_part->part);
  else
    optimize_range= TRUE;
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  if (type == Item_func::LIKE_FUNC)
  {
    bool like_error;
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    char buff1[MAX_FIELD_WIDTH];
    uchar *min_str,*max_str;
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    String tmp(buff1,sizeof(buff1),value->collation.collation),*res;
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    size_t length, offset, min_length, max_length;
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    uint field_length= field->pack_length()+maybe_null;
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    if (!optimize_range)
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      goto end;
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    if (!(res= value->val_str(&tmp)))
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    {
      tree= &null_element;
      goto end;
    }
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    /*
      TODO:
      Check if this was a function. This should have be optimized away
      in the sql_select.cc
    */
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    if (res != &tmp)
    {
      tmp.copy(*res);				// Get own copy
      res= &tmp;
    }
    if (field->cmp_type() != STRING_RESULT)
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      goto end;                                 // Can only optimize strings
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    offset=maybe_null;
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    length=key_part->store_length;

    if (length != key_part->length  + maybe_null)
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    {
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      /* key packed with length prefix */
      offset+= HA_KEY_BLOB_LENGTH;
      field_length= length - HA_KEY_BLOB_LENGTH;
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    }
    else
    {
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      if (unlikely(length < field_length))
      {
	/*
	  This can only happen in a table created with UNIREG where one key
	  overlaps many fields
	*/
	length= field_length;
      }
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      else
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	field_length= length;
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    }
    length+=offset;
5772
    if (!(min_str= (uchar*) alloc_root(alloc, length*2)))
5773
      goto end;
5774

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    max_str=min_str+length;
    if (maybe_null)
      max_str[0]= min_str[0]=0;
5778

5779
    field_length-= maybe_null;
5780
    like_error= my_like_range(field->charset(),
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			      res->ptr(), res->length(),
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			      ((Item_func_like*)(param->cond))->escape,
			      wild_one, wild_many,
5784
			      field_length,
5785
			      (char*) min_str+offset, (char*) max_str+offset,
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			      &min_length, &max_length);
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    if (like_error)				// Can't optimize with LIKE
5788
      goto end;
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5790
    if (offset != maybe_null)			// BLOB or VARCHAR
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    {
      int2store(min_str+maybe_null,min_length);
      int2store(max_str+maybe_null,max_length);
    }
5795 5796
    tree= new (alloc) SEL_ARG(field, min_str, max_str);
    goto end;
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  }

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  if (!optimize_range &&
5800
      type != Item_func::EQ_FUNC &&
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      type != Item_func::EQUAL_FUNC)
5802
    goto end;                                   // Can't optimize this
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5804 5805 5806 5807
  /*
    We can't always use indexes when comparing a string index to a number
    cmp_type() is checked to allow compare of dates to numbers
  */
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  if (field->result_type() == STRING_RESULT &&
      value->result_type() != STRING_RESULT &&
      field->cmp_type() != value->result_type())
5811
    goto end;
5812
  /* For comparison purposes allow invalid dates like 2000-01-32 */
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  orig_sql_mode= field->table->in_use->variables.sql_mode;
5814
  if (value->real_item()->type() == Item::STRING_ITEM &&
5815 5816
      (field->type() == MYSQL_TYPE_DATE ||
       field->type() == MYSQL_TYPE_DATETIME))
5817
    field->table->in_use->variables.sql_mode|= MODE_INVALID_DATES;
5818
  err= value->save_in_field_no_warnings(field, 1);
5819
  if (err > 0)
5820
  {
5821
    if (field->cmp_type() != value->result_type())
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    {
5823 5824 5825 5826 5827 5828 5829 5830 5831
      if ((type == Item_func::EQ_FUNC || type == Item_func::EQUAL_FUNC) &&
          value->result_type() == item_cmp_type(field->result_type(),
                                                value->result_type()))
      {
        tree= new (alloc) SEL_ARG(field, 0, 0);
        tree->type= SEL_ARG::IMPOSSIBLE;
        goto end;
      }
      else
5832 5833
      {
        /*
5834 5835 5836 5837 5838 5839 5840 5841 5842 5843 5844
          TODO: We should return trees of the type SEL_ARG::IMPOSSIBLE
          for the cases like int_field > 999999999999999999999999 as well.
        */
        tree= 0;
        if (err == 3 && field->type() == FIELD_TYPE_DATE &&
            (type == Item_func::GT_FUNC || type == Item_func::GE_FUNC ||
             type == Item_func::LT_FUNC || type == Item_func::LE_FUNC) )
        {
          /*
            We were saving DATETIME into a DATE column, the conversion went ok
            but a non-zero time part was cut off.
5845

5846 5847 5848
            In MySQL's SQL dialect, DATE and DATETIME are compared as datetime
            values. Index over a DATE column uses DATE comparison. Changing 
            from one comparison to the other is possible:
5849

5850 5851
            datetime(date_col)< '2007-12-10 12:34:55' -> date_col<='2007-12-10'
            datetime(date_col)<='2007-12-10 12:34:55' -> date_col<='2007-12-10'
5852

5853 5854
            datetime(date_col)> '2007-12-10 12:34:55' -> date_col>='2007-12-10'
            datetime(date_col)>='2007-12-10 12:34:55' -> date_col>='2007-12-10'
5855

5856 5857 5858 5859 5860 5861 5862
            but we'll need to convert '>' to '>=' and '<' to '<='. This will
            be done together with other types at the end of this function
            (grep for field_is_equal_to_item)
          */
        }
        else
          goto end;
5863
      }
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    }
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    /*
      guaranteed at this point:  err > 0; field and const of same type
      If an integer got bounded (e.g. to within 0..255 / -128..127)
      for < or >, set flags as for <= or >= (no NEAR_MAX / NEAR_MIN)
    */
    else if (err == 1 && field->result_type() == INT_RESULT)
    {
      if (type == Item_func::LT_FUNC && (value->val_int() > 0))
        type = Item_func::LE_FUNC;
      else if (type == Item_func::GT_FUNC &&
               !((Field_num*)field)->unsigned_flag &&
               !((Item_int*)value)->unsigned_flag &&
               (value->val_int() < 0))
        type = Item_func::GE_FUNC;
    }
  }
  else if (err < 0)
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  {
5884
    field->table->in_use->variables.sql_mode= orig_sql_mode;
5885
    /* This happens when we try to insert a NULL field in a not null column */
5886 5887
    tree= &null_element;                        // cmp with NULL is never TRUE
    goto end;
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  }
5889
  field->table->in_use->variables.sql_mode= orig_sql_mode;
5890
  str= (uchar*) alloc_root(alloc, key_part->store_length+1);
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  if (!str)
5892
    goto end;
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  if (maybe_null)
5894 5895 5896
    *str= (uchar) field->is_real_null();        // Set to 1 if null
  field->get_key_image(str+maybe_null, key_part->length,
                       key_part->image_type);
5897 5898
  if (!(tree= new (alloc) SEL_ARG(field, str, str)))
    goto end;                                   // out of memory
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  /*
    Check if we are comparing an UNSIGNED integer with a negative constant.
    In this case we know that:
    (a) (unsigned_int [< | <=] negative_constant) == FALSE
    (b) (unsigned_int [> | >=] negative_constant) == TRUE
    In case (a) the condition is false for all values, and in case (b) it
    is true for all values, so we can avoid unnecessary retrieval and condition
    testing, and we also get correct comparison of unsinged integers with
    negative integers (which otherwise fails because at query execution time
    negative integers are cast to unsigned if compared with unsigned).
   */
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  if (field->result_type() == INT_RESULT &&
      value->result_type() == INT_RESULT &&
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      ((Field_num*)field)->unsigned_flag && !((Item_int*)value)->unsigned_flag)
  {
    longlong item_val= value->val_int();
    if (item_val < 0)
    {
      if (type == Item_func::LT_FUNC || type == Item_func::LE_FUNC)
      {
        tree->type= SEL_ARG::IMPOSSIBLE;
5921
        goto end;
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      }
      if (type == Item_func::GT_FUNC || type == Item_func::GE_FUNC)
5924 5925 5926 5927
      {
        tree= 0;
        goto end;
      }
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    }
  }
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  switch (type) {
  case Item_func::LT_FUNC:
    if (field_is_equal_to_item(field,value))
      tree->max_flag=NEAR_MAX;
    /* fall through */
  case Item_func::LE_FUNC:
    if (!maybe_null)
      tree->min_flag=NO_MIN_RANGE;		/* From start */
    else
    {						// > NULL
      tree->min_value=is_null_string;
      tree->min_flag=NEAR_MIN;
    }
    break;
  case Item_func::GT_FUNC:
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    /* Don't use open ranges for partial key_segments */
    if (field_is_equal_to_item(field,value) &&
        !(key_part->flag & HA_PART_KEY_SEG))
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      tree->min_flag=NEAR_MIN;
    /* fall through */
  case Item_func::GE_FUNC:
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_EQUALS_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_EQUAL;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_DISJOINT_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_DISJOINT;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_INTERSECTS_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_INTERSECT;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_TOUCHES_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_INTERSECT;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_CROSSES_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_INTERSECT;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_WITHIN_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_WITHIN;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_CONTAINS_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_CONTAIN;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  case Item_func::SP_OVERLAPS_FUNC:
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    tree->min_flag=GEOM_FLAG | HA_READ_MBR_INTERSECT;// NEAR_MIN;//512;
    tree->max_flag=NO_MAX_RANGE;
    break;
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  default:
    break;
  }
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end:
  param->thd->mem_root= alloc;
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  DBUG_RETURN(tree);
}


/******************************************************************************
** Tree manipulation functions
** If tree is 0 it means that the condition can't be tested. It refers
** to a non existent table or to a field in current table with isn't a key.
** The different tree flags:
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** IMPOSSIBLE:	 Condition is never TRUE
** ALWAYS:	 Condition is always TRUE
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** MAYBE:	 Condition may exists when tables are read
** MAYBE_KEY:	 Condition refers to a key that may be used in join loop
** KEY_RANGE:	 Condition uses a key
******************************************************************************/

/*
6012 6013
  Add a new key test to a key when scanning through all keys
  This will never be called for same key parts.
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*/

static SEL_ARG *
sel_add(SEL_ARG *key1,SEL_ARG *key2)
{
  SEL_ARG *root,**key_link;

  if (!key1)
    return key2;
  if (!key2)
    return key1;

  key_link= &root;
  while (key1 && key2)
  {
    if (key1->part < key2->part)
    {
      *key_link= key1;
      key_link= &key1->next_key_part;
      key1=key1->next_key_part;
    }
    else
    {
      *key_link= key2;
      key_link= &key2->next_key_part;
      key2=key2->next_key_part;
    }
  }
  *key_link=key1 ? key1 : key2;
  return root;
}

#define CLONE_KEY1_MAYBE 1
#define CLONE_KEY2_MAYBE 2
#define swap_clone_flag(A) ((A & 1) << 1) | ((A & 2) >> 1)


static SEL_TREE *
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tree_and(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
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{
  DBUG_ENTER("tree_and");
  if (!tree1)
    DBUG_RETURN(tree2);
  if (!tree2)
    DBUG_RETURN(tree1);
  if (tree1->type == SEL_TREE::IMPOSSIBLE || tree2->type == SEL_TREE::ALWAYS)
    DBUG_RETURN(tree1);
  if (tree2->type == SEL_TREE::IMPOSSIBLE || tree1->type == SEL_TREE::ALWAYS)
    DBUG_RETURN(tree2);
  if (tree1->type == SEL_TREE::MAYBE)
  {
    if (tree2->type == SEL_TREE::KEY)
      tree2->type=SEL_TREE::KEY_SMALLER;
    DBUG_RETURN(tree2);
  }
  if (tree2->type == SEL_TREE::MAYBE)
  {
    tree1->type=SEL_TREE::KEY_SMALLER;
    DBUG_RETURN(tree1);
  }
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  key_map  result_keys;
  result_keys.clear_all();
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  /* Join the trees key per key */
  SEL_ARG **key1,**key2,**end;
  for (key1= tree1->keys,key2= tree2->keys,end=key1+param->keys ;
       key1 != end ; key1++,key2++)
  {
    uint flag=0;
    if (*key1 || *key2)
    {
      if (*key1 && !(*key1)->simple_key())
	flag|=CLONE_KEY1_MAYBE;
      if (*key2 && !(*key2)->simple_key())
	flag|=CLONE_KEY2_MAYBE;
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      *key1=key_and(param, *key1, *key2, flag);
6090
      if (*key1 && (*key1)->type == SEL_ARG::IMPOSSIBLE)
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      {
	tree1->type= SEL_TREE::IMPOSSIBLE;
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        DBUG_RETURN(tree1);
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      }
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      result_keys.set_bit(key1 - tree1->keys);
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#ifdef EXTRA_DEBUG
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        if (*key1 && param->alloced_sel_args < SEL_ARG::MAX_SEL_ARGS) 
          (*key1)->test_use_count(*key1);
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#endif
    }
  }
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  tree1->keys_map= result_keys;
  /* dispose index_merge if there is a "range" option */
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  if (!result_keys.is_clear_all())
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  {
    tree1->merges.empty();
    DBUG_RETURN(tree1);
  }

  /* ok, both trees are index_merge trees */
  imerge_list_and_list(&tree1->merges, &tree2->merges);
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  DBUG_RETURN(tree1);
}


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/*
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  Check if two SEL_TREES can be combined into one (i.e. a single key range
  read can be constructed for "cond_of_tree1 OR cond_of_tree2" ) without
6119
  using index_merge.
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*/

6122 6123
bool sel_trees_can_be_ored(SEL_TREE *tree1, SEL_TREE *tree2, 
                           RANGE_OPT_PARAM* param)
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{
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  key_map common_keys= tree1->keys_map;
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  DBUG_ENTER("sel_trees_can_be_ored");
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  common_keys.intersect(tree2->keys_map);
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  if (common_keys.is_clear_all())
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    DBUG_RETURN(FALSE);
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  /* trees have a common key, check if they refer to same key part */
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  SEL_ARG **key1,**key2;
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  for (uint key_no=0; key_no < param->keys; key_no++)
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  {
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    if (common_keys.is_set(key_no))
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    {
      key1= tree1->keys + key_no;
      key2= tree2->keys + key_no;
      if ((*key1)->part == (*key2)->part)
      {
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        DBUG_RETURN(TRUE);
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      }
    }
  }
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  DBUG_RETURN(FALSE);
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}
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/*
  Remove the trees that are not suitable for record retrieval.
  SYNOPSIS
    param  Range analysis parameter
    tree   Tree to be processed, tree->type is KEY or KEY_SMALLER
 
  DESCRIPTION
    This function walks through tree->keys[] and removes the SEL_ARG* trees
    that are not "maybe" trees (*) and cannot be used to construct quick range
    selects.
    (*) - have type MAYBE or MAYBE_KEY. Perhaps we should remove trees of
          these types here as well.

    A SEL_ARG* tree cannot be used to construct quick select if it has
    tree->part != 0. (e.g. it could represent "keypart2 < const").

    WHY THIS FUNCTION IS NEEDED
    
    Normally we allow construction of SEL_TREE objects that have SEL_ARG
    trees that do not allow quick range select construction. For example for
    " keypart1=1 AND keypart2=2 " the execution will proceed as follows:
    tree1= SEL_TREE { SEL_ARG{keypart1=1} }
    tree2= SEL_TREE { SEL_ARG{keypart2=2} } -- can't make quick range select
                                               from this
    call tree_and(tree1, tree2) -- this joins SEL_ARGs into a usable SEL_ARG
                                   tree.
    
    There is an exception though: when we construct index_merge SEL_TREE,
    any SEL_ARG* tree that cannot be used to construct quick range select can
    be removed, because current range analysis code doesn't provide any way
    that tree could be later combined with another tree.
    Consider an example: we should not construct
    st1 = SEL_TREE { 
      merges = SEL_IMERGE { 
                            SEL_TREE(t.key1part1 = 1), 
                            SEL_TREE(t.key2part2 = 2)   -- (*)
                          } 
                   };
    because 
     - (*) cannot be used to construct quick range select, 
     - There is no execution path that would cause (*) to be converted to 
       a tree that could be used.

    The latter is easy to verify: first, notice that the only way to convert
    (*) into a usable tree is to call tree_and(something, (*)).

    Second look at what tree_and/tree_or function would do when passed a
    SEL_TREE that has the structure like st1 tree has, and conlcude that 
    tree_and(something, (*)) will not be called.

  RETURN
    0  Ok, some suitable trees left
    1  No tree->keys[] left.
*/

static bool remove_nonrange_trees(RANGE_OPT_PARAM *param, SEL_TREE *tree)
{
  bool res= FALSE;
  for (uint i=0; i < param->keys; i++)
  {
    if (tree->keys[i])
    {
      if (tree->keys[i]->part)
6213
      {
6214
        tree->keys[i]= NULL;
6215 6216
        tree->keys_map.clear_bit(i);
      }
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      else
        res= TRUE;
    }
  }
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  return !res;
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}


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static SEL_TREE *
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tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
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{
  DBUG_ENTER("tree_or");
  if (!tree1 || !tree2)
    DBUG_RETURN(0);
  if (tree1->type == SEL_TREE::IMPOSSIBLE || tree2->type == SEL_TREE::ALWAYS)
    DBUG_RETURN(tree2);
  if (tree2->type == SEL_TREE::IMPOSSIBLE || tree1->type == SEL_TREE::ALWAYS)
    DBUG_RETURN(tree1);
  if (tree1->type == SEL_TREE::MAYBE)
    DBUG_RETURN(tree1);				// Can't use this
  if (tree2->type == SEL_TREE::MAYBE)
    DBUG_RETURN(tree2);

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  SEL_TREE *result= 0;
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  key_map  result_keys;
  result_keys.clear_all();
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  if (sel_trees_can_be_ored(tree1, tree2, param))
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  {
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    /* Join the trees key per key */
    SEL_ARG **key1,**key2,**end;
    for (key1= tree1->keys,key2= tree2->keys,end= key1+param->keys ;
         key1 != end ; key1++,key2++)
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    {
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      *key1=key_or(param, *key1, *key2);
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      if (*key1)
      {
        result=tree1;				// Added to tree1
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        result_keys.set_bit(key1 - tree1->keys);
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#ifdef EXTRA_DEBUG
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        if (param->alloced_sel_args < SEL_ARG::MAX_SEL_ARGS) 
          (*key1)->test_use_count(*key1);
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#endif
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      }
    }
    if (result)
      result->keys_map= result_keys;
  }
  else
  {
    /* ok, two trees have KEY type but cannot be used without index merge */
    if (tree1->merges.is_empty() && tree2->merges.is_empty())
    {
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      if (param->remove_jump_scans)
      {
        bool no_trees= remove_nonrange_trees(param, tree1);
        no_trees= no_trees || remove_nonrange_trees(param, tree2);
        if (no_trees)
          DBUG_RETURN(new SEL_TREE(SEL_TREE::ALWAYS));
      }
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      SEL_IMERGE *merge;
      /* both trees are "range" trees, produce new index merge structure */
      if (!(result= new SEL_TREE()) || !(merge= new SEL_IMERGE()) ||
          (result->merges.push_back(merge)) ||
          (merge->or_sel_tree(param, tree1)) ||
          (merge->or_sel_tree(param, tree2)))
        result= NULL;
      else
        result->type= tree1->type;
    }
    else if (!tree1->merges.is_empty() && !tree2->merges.is_empty())
    {
      if (imerge_list_or_list(param, &tree1->merges, &tree2->merges))
        result= new SEL_TREE(SEL_TREE::ALWAYS);
      else
        result= tree1;
    }
    else
    {
      /* one tree is index merge tree and another is range tree */
      if (tree1->merges.is_empty())
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        swap_variables(SEL_TREE*, tree1, tree2);
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      if (param->remove_jump_scans && remove_nonrange_trees(param, tree2))
         DBUG_RETURN(new SEL_TREE(SEL_TREE::ALWAYS));
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      /* add tree2 to tree1->merges, checking if it collapses to ALWAYS */
      if (imerge_list_or_tree(param, &tree1->merges, tree2))
        result= new SEL_TREE(SEL_TREE::ALWAYS);
      else
        result= tree1;
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    }
  }
  DBUG_RETURN(result);
}


/* And key trees where key1->part < key2 -> part */

static SEL_ARG *
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and_all_keys(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2, 
             uint clone_flag)
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{
  SEL_ARG *next;
  ulong use_count=key1->use_count;

  if (key1->elements != 1)
  {
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    key2->use_count+=key1->elements-1; //psergey: why we don't count that key1 has n-k-p?
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    key2->increment_use_count((int) key1->elements-1);
  }
  if (key1->type == SEL_ARG::MAYBE_KEY)
  {
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    key1->right= key1->left= &null_element;
    key1->next= key1->prev= 0;
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  }
  for (next=key1->first(); next ; next=next->next)
  {
    if (next->next_key_part)
    {
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      SEL_ARG *tmp= key_and(param, next->next_key_part, key2, clone_flag);
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      if (tmp && tmp->type == SEL_ARG::IMPOSSIBLE)
      {
	key1=key1->tree_delete(next);
	continue;
      }
      next->next_key_part=tmp;
      if (use_count)
	next->increment_use_count(use_count);
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      if (param->alloced_sel_args > SEL_ARG::MAX_SEL_ARGS)
        break;
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    }
    else
      next->next_key_part=key2;
  }
  if (!key1)
    return &null_element;			// Impossible ranges
  key1->use_count++;
  return key1;
}


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/*
  Produce a SEL_ARG graph that represents "key1 AND key2"

  SYNOPSIS
    key_and()
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      param   Range analysis context (needed to track if we have allocated
              too many SEL_ARGs)
      key1    First argument, root of its RB-tree
      key2    Second argument, root of its RB-tree
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  RETURN
    RB-tree root of the resulting SEL_ARG graph.
    NULL if the result of AND operation is an empty interval {0}.
*/

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static SEL_ARG *
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key_and(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2, uint clone_flag)
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{
  if (!key1)
    return key2;
  if (!key2)
    return key1;
  if (key1->part != key2->part)
  {
    if (key1->part > key2->part)
    {
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      swap_variables(SEL_ARG *, key1, key2);
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      clone_flag=swap_clone_flag(clone_flag);
    }
    // key1->part < key2->part
    key1->use_count--;
    if (key1->use_count > 0)
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      if (!(key1= key1->clone_tree(param)))
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	return 0;				// OOM
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    return and_all_keys(param, key1, key2, clone_flag);
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  }

  if (((clone_flag & CLONE_KEY2_MAYBE) &&
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       !(clone_flag & CLONE_KEY1_MAYBE) &&
       key2->type != SEL_ARG::MAYBE_KEY) ||
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      key1->type == SEL_ARG::MAYBE_KEY)
  {						// Put simple key in key2
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    swap_variables(SEL_ARG *, key1, key2);
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    clone_flag=swap_clone_flag(clone_flag);
  }

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  /* If one of the key is MAYBE_KEY then the found region may be smaller */
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  if (key2->type == SEL_ARG::MAYBE_KEY)
  {
    if (key1->use_count > 1)
    {
      key1->use_count--;
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      if (!(key1=key1->clone_tree(param)))
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	return 0;				// OOM
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      key1->use_count++;
    }
    if (key1->type == SEL_ARG::MAYBE_KEY)
    {						// Both are maybe key
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      key1->next_key_part=key_and(param, key1->next_key_part, 
                                  key2->next_key_part, clone_flag);
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      if (key1->next_key_part &&
	  key1->next_key_part->type == SEL_ARG::IMPOSSIBLE)
	return key1;
    }
    else
    {
      key1->maybe_smaller();
      if (key2->next_key_part)
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      {
	key1->use_count--;			// Incremented in and_all_keys
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	return and_all_keys(param, key1, key2, clone_flag);
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      }
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      key2->use_count--;			// Key2 doesn't have a tree
    }
    return key1;
  }

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  if ((key1->min_flag | key2->min_flag) & GEOM_FLAG)
  {
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    /* TODO: why not leave one of the trees? */
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    key1->free_tree();
    key2->free_tree();
    return 0;					// Can't optimize this
  }

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  if ((key1->min_flag | key2->min_flag) & GEOM_FLAG)
  {
    key1->free_tree();
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    key2->free_tree();
    return 0;					// Can't optimize this
  }

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  key1->use_count--;
  key2->use_count--;
  SEL_ARG *e1=key1->first(), *e2=key2->first(), *new_tree=0;

  while (e1 && e2)
  {
    int cmp=e1->cmp_min_to_min(e2);
    if (cmp < 0)
    {
      if (get_range(&e1,&e2,key1))
	continue;
    }
    else if (get_range(&e2,&e1,key2))
      continue;
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    SEL_ARG *next=key_and(param, e1->next_key_part, e2->next_key_part,
                          clone_flag);
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    e1->increment_use_count(1);
    e2->increment_use_count(1);
    if (!next || next->type != SEL_ARG::IMPOSSIBLE)
    {
      SEL_ARG *new_arg= e1->clone_and(e2);
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      if (!new_arg)
	return &null_element;			// End of memory
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      new_arg->next_key_part=next;
      if (!new_tree)
      {
	new_tree=new_arg;
      }
      else
	new_tree=new_tree->insert(new_arg);
    }
    if (e1->cmp_max_to_max(e2) < 0)
      e1=e1->next;				// e1 can't overlapp next e2
    else
      e2=e2->next;
  }
  key1->free_tree();
  key2->free_tree();
  if (!new_tree)
    return &null_element;			// Impossible range
  return new_tree;
}


static bool
get_range(SEL_ARG **e1,SEL_ARG **e2,SEL_ARG *root1)
{
  (*e1)=root1->find_range(*e2);			// first e1->min < e2->min
  if ((*e1)->cmp_max_to_min(*e2) < 0)
  {
    if (!((*e1)=(*e1)->next))
      return 1;
    if ((*e1)->cmp_min_to_max(*e2) > 0)
    {
      (*e2)=(*e2)->next;
      return 1;
    }
  }
  return 0;
}


static SEL_ARG *
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key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
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{
  if (!key1)
  {
    if (key2)
    {
      key2->use_count--;
      key2->free_tree();
    }
    return 0;
  }
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  if (!key2)
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  {
    key1->use_count--;
    key1->free_tree();
    return 0;
  }
  key1->use_count--;
  key2->use_count--;

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  if (key1->part != key2->part || 
      (key1->min_flag | key2->min_flag) & GEOM_FLAG)
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  {
    key1->free_tree();
    key2->free_tree();
    return 0;					// Can't optimize this
  }

  // If one of the key is MAYBE_KEY then the found region may be bigger
  if (key1->type == SEL_ARG::MAYBE_KEY)
  {
    key2->free_tree();
    key1->use_count++;
    return key1;
  }
  if (key2->type == SEL_ARG::MAYBE_KEY)
  {
    key1->free_tree();
    key2->use_count++;
    return key2;
  }

  if (key1->use_count > 0)
  {
    if (key2->use_count == 0 || key1->elements > key2->elements)
    {
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      swap_variables(SEL_ARG *,key1,key2);
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    }
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    if (key1->use_count > 0 || !(key1=key1->clone_tree(param)))
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      return 0;					// OOM
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  }

  // Add tree at key2 to tree at key1
  bool key2_shared=key2->use_count != 0;
  key1->maybe_flag|=key2->maybe_flag;

  for (key2=key2->first(); key2; )
  {
    SEL_ARG *tmp=key1->find_range(key2);	// Find key1.min <= key2.min
    int cmp;

    if (!tmp)
    {
      tmp=key1->first();			// tmp.min > key2.min
      cmp= -1;
    }
    else if ((cmp=tmp->cmp_max_to_min(key2)) < 0)
    {						// Found tmp.max < key2.min
      SEL_ARG *next=tmp->next;
      if (cmp == -2 && eq_tree(tmp->next_key_part,key2->next_key_part))
      {
	// Join near ranges like tmp.max < 0 and key2.min >= 0
	SEL_ARG *key2_next=key2->next;
	if (key2_shared)
	{
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	  if (!(key2=new SEL_ARG(*key2)))
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	    return 0;		// out of memory
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	  key2->increment_use_count(key1->use_count+1);
	  key2->next=key2_next;			// New copy of key2
	}
	key2->copy_min(tmp);
	if (!(key1=key1->tree_delete(tmp)))
	{					// Only one key in tree
	  key1=key2;
	  key1->make_root();
	  key2=key2_next;
	  break;
	}
      }
      if (!(tmp=next))				// tmp.min > key2.min
	break;					// Copy rest of key2
    }
    if (cmp < 0)
    {						// tmp.min > key2.min
      int tmp_cmp;
      if ((tmp_cmp=tmp->cmp_min_to_max(key2)) > 0) // if tmp.min > key2.max
      {
	if (tmp_cmp == 2 && eq_tree(tmp->next_key_part,key2->next_key_part))
	{					// ranges are connected
	  tmp->copy_min_to_min(key2);
	  key1->merge_flags(key2);
	  if (tmp->min_flag & NO_MIN_RANGE &&
	      tmp->max_flag & NO_MAX_RANGE)
	  {
	    if (key1->maybe_flag)
	      return new SEL_ARG(SEL_ARG::MAYBE_KEY);
	    return 0;
	  }
	  key2->increment_use_count(-1);	// Free not used tree
	  key2=key2->next;
	  continue;
	}
	else
	{
	  SEL_ARG *next=key2->next;		// Keys are not overlapping
	  if (key2_shared)
	  {
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	    SEL_ARG *cpy= new SEL_ARG(*key2);	// Must make copy
	    if (!cpy)
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	      return 0;				// OOM
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	    key1=key1->insert(cpy);
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	    key2->increment_use_count(key1->use_count+1);
	  }
	  else
	    key1=key1->insert(key2);		// Will destroy key2_root
	  key2=next;
	  continue;
	}
      }
    }

    // tmp.max >= key2.min && tmp.min <= key.max  (overlapping ranges)
    if (eq_tree(tmp->next_key_part,key2->next_key_part))
    {
      if (tmp->is_same(key2))
      {
	tmp->merge_flags(key2);			// Copy maybe flags
	key2->increment_use_count(-1);		// Free not used tree
      }
      else
      {
	SEL_ARG *last=tmp;
	while (last->next && last->next->cmp_min_to_max(key2) <= 0 &&
	       eq_tree(last->next->next_key_part,key2->next_key_part))
	{
	  SEL_ARG *save=last;
	  last=last->next;
	  key1=key1->tree_delete(save);
	}
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        last->copy_min(tmp);
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	if (last->copy_min(key2) || last->copy_max(key2))
	{					// Full range
	  key1->free_tree();
	  for (; key2 ; key2=key2->next)
	    key2->increment_use_count(-1);	// Free not used tree
	  if (key1->maybe_flag)
	    return new SEL_ARG(SEL_ARG::MAYBE_KEY);
	  return 0;
	}
      }
      key2=key2->next;
      continue;
    }

    if (cmp >= 0 && tmp->cmp_min_to_min(key2) < 0)
    {						// tmp.min <= x < key2.min
      SEL_ARG *new_arg=tmp->clone_first(key2);
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      if (!new_arg)
	return 0;				// OOM
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      if ((new_arg->next_key_part= key1->next_key_part))
	new_arg->increment_use_count(key1->use_count+1);
      tmp->copy_min_to_min(key2);
      key1=key1->insert(new_arg);
    }

    // tmp.min >= key2.min && tmp.min <= key2.max
    SEL_ARG key(*key2);				// Get copy we can modify
    for (;;)
    {
      if (tmp->cmp_min_to_min(&key) > 0)
      {						// key.min <= x < tmp.min
	SEL_ARG *new_arg=key.clone_first(tmp);
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	if (!new_arg)
	  return 0;				// OOM
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	if ((new_arg->next_key_part=key.next_key_part))
	  new_arg->increment_use_count(key1->use_count+1);
	key1=key1->insert(new_arg);
      }
      if ((cmp=tmp->cmp_max_to_max(&key)) <= 0)
      {						// tmp.min. <= x <= tmp.max
	tmp->maybe_flag|= key.maybe_flag;
	key.increment_use_count(key1->use_count+1);
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	tmp->next_key_part= key_or(param, tmp->next_key_part, key.next_key_part);
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	if (!cmp)				// Key2 is ready
	  break;
	key.copy_max_to_min(tmp);
	if (!(tmp=tmp->next))
	{
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	  SEL_ARG *tmp2= new SEL_ARG(key);
	  if (!tmp2)
	    return 0;				// OOM
	  key1=key1->insert(tmp2);
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	  key2=key2->next;
	  goto end;
	}
	if (tmp->cmp_min_to_max(&key) > 0)
	{
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	  SEL_ARG *tmp2= new SEL_ARG(key);
	  if (!tmp2)
	    return 0;				// OOM
	  key1=key1->insert(tmp2);
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	  break;
	}
      }
      else
      {
	SEL_ARG *new_arg=tmp->clone_last(&key); // tmp.min <= x <= key.max
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	if (!new_arg)
	  return 0;				// OOM
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	tmp->copy_max_to_min(&key);
	tmp->increment_use_count(key1->use_count+1);
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	/* Increment key count as it may be used for next loop */
	key.increment_use_count(1);
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	new_arg->next_key_part= key_or(param, tmp->next_key_part, key.next_key_part);
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	key1=key1->insert(new_arg);
	break;
      }
    }
    key2=key2->next;
  }

end:
  while (key2)
  {
    SEL_ARG *next=key2->next;
    if (key2_shared)
    {
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      SEL_ARG *tmp=new SEL_ARG(*key2);		// Must make copy
      if (!tmp)
	return 0;
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      key2->increment_use_count(key1->use_count+1);
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      key1=key1->insert(tmp);
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    }
    else
      key1=key1->insert(key2);			// Will destroy key2_root
    key2=next;
  }
  key1->use_count++;
  return key1;
}


/* Compare if two trees are equal */

static bool eq_tree(SEL_ARG* a,SEL_ARG *b)
{
  if (a == b)
    return 1;
  if (!a || !b || !a->is_same(b))
    return 0;
  if (a->left != &null_element && b->left != &null_element)
  {
    if (!eq_tree(a->left,b->left))
      return 0;
  }
  else if (a->left != &null_element || b->left != &null_element)
    return 0;
  if (a->right != &null_element && b->right != &null_element)
  {
    if (!eq_tree(a->right,b->right))
      return 0;
  }
  else if (a->right != &null_element || b->right != &null_element)
    return 0;
  if (a->next_key_part != b->next_key_part)
  {						// Sub range
    if (!a->next_key_part != !b->next_key_part ||
	!eq_tree(a->next_key_part, b->next_key_part))
      return 0;
  }
  return 1;
}


SEL_ARG *
SEL_ARG::insert(SEL_ARG *key)
{
  SEL_ARG *element,**par,*last_element;
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  LINT_INIT(par);
  LINT_INIT(last_element);
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  for (element= this; element != &null_element ; )
  {
    last_element=element;
    if (key->cmp_min_to_min(element) > 0)
    {
      par= &element->right; element= element->right;
    }
    else
    {
      par = &element->left; element= element->left;
    }
  }
  *par=key;
  key->parent=last_element;
	/* Link in list */
  if (par == &last_element->left)
  {
    key->next=last_element;
    if ((key->prev=last_element->prev))
      key->prev->next=key;
    last_element->prev=key;
  }
  else
  {
    if ((key->next=last_element->next))
      key->next->prev=key;
    key->prev=last_element;
    last_element->next=key;
  }
  key->left=key->right= &null_element;
  SEL_ARG *root=rb_insert(key);			// rebalance tree
  root->use_count=this->use_count;		// copy root info
  root->elements= this->elements+1;
  root->maybe_flag=this->maybe_flag;
  return root;
}


/*
** Find best key with min <= given key
** Because the call context this should never return 0 to get_range
*/

SEL_ARG *
SEL_ARG::find_range(SEL_ARG *key)
{
  SEL_ARG *element=this,*found=0;

  for (;;)
  {
    if (element == &null_element)
      return found;
    int cmp=element->cmp_min_to_min(key);
    if (cmp == 0)
      return element;
    if (cmp < 0)
    {
      found=element;
      element=element->right;
    }
    else
      element=element->left;
  }
}


/*
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  Remove a element from the tree

  SYNOPSIS
    tree_delete()
    key		Key that is to be deleted from tree (this)
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  NOTE
    This also frees all sub trees that is used by the element

  RETURN
    root of new tree (with key deleted)
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*/

SEL_ARG *
SEL_ARG::tree_delete(SEL_ARG *key)
{
  enum leaf_color remove_color;
  SEL_ARG *root,*nod,**par,*fix_par;
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  DBUG_ENTER("tree_delete");

  root=this;
  this->parent= 0;
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  /* Unlink from list */
  if (key->prev)
    key->prev->next=key->next;
  if (key->next)
    key->next->prev=key->prev;
  key->increment_use_count(-1);
  if (!key->parent)
    par= &root;
  else
    par=key->parent_ptr();

  if (key->left == &null_element)
  {
    *par=nod=key->right;
    fix_par=key->parent;
    if (nod != &null_element)
      nod->parent=fix_par;
    remove_color= key->color;
  }
  else if (key->right == &null_element)
  {
    *par= nod=key->left;
    nod->parent=fix_par=key->parent;
    remove_color= key->color;
  }
  else
  {
    SEL_ARG *tmp=key->next;			// next bigger key (exist!)
    nod= *tmp->parent_ptr()= tmp->right;	// unlink tmp from tree
    fix_par=tmp->parent;
    if (nod != &null_element)
      nod->parent=fix_par;
    remove_color= tmp->color;

    tmp->parent=key->parent;			// Move node in place of key
    (tmp->left=key->left)->parent=tmp;
    if ((tmp->right=key->right) != &null_element)
      tmp->right->parent=tmp;
    tmp->color=key->color;
    *par=tmp;
    if (fix_par == key)				// key->right == key->next
      fix_par=tmp;				// new parent of nod
  }

  if (root == &null_element)
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    DBUG_RETURN(0);				// Maybe root later
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  if (remove_color == BLACK)
    root=rb_delete_fixup(root,nod,fix_par);
  test_rb_tree(root,root->parent);

  root->use_count=this->use_count;		// Fix root counters
  root->elements=this->elements-1;
  root->maybe_flag=this->maybe_flag;
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  DBUG_RETURN(root);
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}


	/* Functions to fix up the tree after insert and delete */

static void left_rotate(SEL_ARG **root,SEL_ARG *leaf)
{
  SEL_ARG *y=leaf->right;
  leaf->right=y->left;
  if (y->left != &null_element)
    y->left->parent=leaf;
  if (!(y->parent=leaf->parent))
    *root=y;
  else
    *leaf->parent_ptr()=y;
  y->left=leaf;
  leaf->parent=y;
}

static void right_rotate(SEL_ARG **root,SEL_ARG *leaf)
{
  SEL_ARG *y=leaf->left;
  leaf->left=y->right;
  if (y->right != &null_element)
    y->right->parent=leaf;
  if (!(y->parent=leaf->parent))
    *root=y;
  else
    *leaf->parent_ptr()=y;
  y->right=leaf;
  leaf->parent=y;
}


SEL_ARG *
SEL_ARG::rb_insert(SEL_ARG *leaf)
{
  SEL_ARG *y,*par,*par2,*root;
  root= this; root->parent= 0;

  leaf->color=RED;
  while (leaf != root && (par= leaf->parent)->color == RED)
  {					// This can't be root or 1 level under
    if (par == (par2= leaf->parent->parent)->left)
    {
      y= par2->right;
      if (y->color == RED)
      {
	par->color=BLACK;
	y->color=BLACK;
	leaf=par2;
	leaf->color=RED;		/* And the loop continues */
      }
      else
      {
	if (leaf == par->right)
	{
	  left_rotate(&root,leaf->parent);
	  par=leaf;			/* leaf is now parent to old leaf */
	}
	par->color=BLACK;
	par2->color=RED;
	right_rotate(&root,par2);
	break;
      }
    }
    else
    {
      y= par2->left;
      if (y->color == RED)
      {
	par->color=BLACK;
	y->color=BLACK;
	leaf=par2;
	leaf->color=RED;		/* And the loop continues */
      }
      else
      {
	if (leaf == par->left)
	{
	  right_rotate(&root,par);
	  par=leaf;
	}
	par->color=BLACK;
	par2->color=RED;
	left_rotate(&root,par2);
	break;
      }
    }
  }
  root->color=BLACK;
  test_rb_tree(root,root->parent);
  return root;
}


SEL_ARG *rb_delete_fixup(SEL_ARG *root,SEL_ARG *key,SEL_ARG *par)
{
  SEL_ARG *x,*w;
  root->parent=0;

  x= key;
  while (x != root && x->color == SEL_ARG::BLACK)
  {
    if (x == par->left)
    {
      w=par->right;
      if (w->color == SEL_ARG::RED)
      {
	w->color=SEL_ARG::BLACK;
	par->color=SEL_ARG::RED;
	left_rotate(&root,par);
	w=par->right;
      }
      if (w->left->color == SEL_ARG::BLACK && w->right->color == SEL_ARG::BLACK)
      {
	w->color=SEL_ARG::RED;
	x=par;
      }
      else
      {
	if (w->right->color == SEL_ARG::BLACK)
	{
	  w->left->color=SEL_ARG::BLACK;
	  w->color=SEL_ARG::RED;
	  right_rotate(&root,w);
	  w=par->right;
	}
	w->color=par->color;
	par->color=SEL_ARG::BLACK;
	w->right->color=SEL_ARG::BLACK;
	left_rotate(&root,par);
	x=root;
	break;
      }
    }
    else
    {
      w=par->left;
      if (w->color == SEL_ARG::RED)
      {
	w->color=SEL_ARG::BLACK;
	par->color=SEL_ARG::RED;
	right_rotate(&root,par);
	w=par->left;
      }
      if (w->right->color == SEL_ARG::BLACK && w->left->color == SEL_ARG::BLACK)
      {
	w->color=SEL_ARG::RED;
	x=par;
      }
      else
      {
	if (w->left->color == SEL_ARG::BLACK)
	{
	  w->right->color=SEL_ARG::BLACK;
	  w->color=SEL_ARG::RED;
	  left_rotate(&root,w);
	  w=par->left;
	}
	w->color=par->color;
	par->color=SEL_ARG::BLACK;
	w->left->color=SEL_ARG::BLACK;
	right_rotate(&root,par);
	x=root;
	break;
      }
    }
    par=x->parent;
  }
  x->color=SEL_ARG::BLACK;
  return root;
}


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	/* Test that the properties for a red-black tree hold */
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#ifdef EXTRA_DEBUG
int test_rb_tree(SEL_ARG *element,SEL_ARG *parent)
{
  int count_l,count_r;

  if (element == &null_element)
    return 0;					// Found end of tree
  if (element->parent != parent)
  {
    sql_print_error("Wrong tree: Parent doesn't point at parent");
    return -1;
  }
  if (element->color == SEL_ARG::RED &&
      (element->left->color == SEL_ARG::RED ||
       element->right->color == SEL_ARG::RED))
  {
    sql_print_error("Wrong tree: Found two red in a row");
    return -1;
  }
  if (element->left == element->right && element->left != &null_element)
  {						// Dummy test
    sql_print_error("Wrong tree: Found right == left");
    return -1;
  }
  count_l=test_rb_tree(element->left,element);
  count_r=test_rb_tree(element->right,element);
  if (count_l >= 0 && count_r >= 0)
  {
    if (count_l == count_r)
      return count_l+(element->color == SEL_ARG::BLACK);
    sql_print_error("Wrong tree: Incorrect black-count: %d - %d",
	    count_l,count_r);
  }
  return -1;					// Error, no more warnings
}

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/*
  Count how many times SEL_ARG graph "root" refers to its part "key"
  
  SYNOPSIS
    count_key_part_usage()
      root  An RB-Root node in a SEL_ARG graph.
      key   Another RB-Root node in that SEL_ARG graph.

  DESCRIPTION
    The passed "root" node may refer to "key" node via root->next_key_part,
    root->next->n

    This function counts how many times the node "key" is referred (via
    SEL_ARG::next_key_part) by 
     - intervals of RB-tree pointed by "root", 
     - intervals of RB-trees that are pointed by SEL_ARG::next_key_part from 
       intervals of RB-tree pointed by "root",
     - and so on.
    
    Here is an example (horizontal links represent next_key_part pointers, 
    vertical links - next/prev prev pointers):  
    
         +----+               $
         |root|-----------------+
         +----+               $ |
           |                  $ |
           |                  $ |
         +----+       +---+   $ |     +---+    Here the return value
         |    |- ... -|   |---$-+--+->|key|    will be 4.
         +----+       +---+   $ |  |  +---+
           |                  $ |  |
          ...                 $ |  |
           |                  $ |  |
         +----+   +---+       $ |  |
         |    |---|   |---------+  |
         +----+   +---+       $    |
           |        |         $    |
          ...     +---+       $    |
                  |   |------------+
                  +---+       $
  RETURN 
    Number of links to "key" from nodes reachable from "root".
*/

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static ulong count_key_part_usage(SEL_ARG *root, SEL_ARG *key)
{
  ulong count= 0;
  for (root=root->first(); root ; root=root->next)
  {
    if (root->next_key_part)
    {
      if (root->next_key_part == key)
	count++;
      if (root->next_key_part->part < key->part)
	count+=count_key_part_usage(root->next_key_part,key);
    }
  }
  return count;
}


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/*
  Check if SEL_ARG::use_count value is correct

  SYNOPSIS
    SEL_ARG::test_use_count()
      root  The root node of the SEL_ARG graph (an RB-tree root node that
            has the least value of sel_arg->part in the entire graph, and
            thus is the "origin" of the graph)

  DESCRIPTION
    Check if SEL_ARG::use_count value is correct. See the definition of
    use_count for what is "correct".
*/

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void SEL_ARG::test_use_count(SEL_ARG *root)
{
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  uint e_count=0;
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  if (this == root && use_count != 1)
  {
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    sql_print_information("Use_count: Wrong count %lu for root",use_count);
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    return;
  }
  if (this->type != SEL_ARG::KEY_RANGE)
    return;
  for (SEL_ARG *pos=first(); pos ; pos=pos->next)
  {
    e_count++;
    if (pos->next_key_part)
    {
      ulong count=count_key_part_usage(root,pos->next_key_part);
      if (count > pos->next_key_part->use_count)
      {
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        sql_print_information("Use_count: Wrong count for key at 0x%lx, %lu "
                              "should be %lu", (long unsigned int)pos,
                              pos->next_key_part->use_count, count);
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	return;
      }
      pos->next_key_part->test_use_count(root);
    }
  }
  if (e_count != elements)
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    sql_print_warning("Wrong use count: %u (should be %u) for tree at 0x%lx",
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                      e_count, elements, (long unsigned int) this);
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}

#endif


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/*
  Calculate estimate of number records that will be retrieved by a range
  scan on given index using given SEL_ARG intervals tree.
  SYNOPSIS
    check_quick_select
      param  Parameter from test_quick_select
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      idx               Number of index to use in tree->keys
      tree              Transformed selection condition, tree->keys[idx]
                        holds the range tree to be used for scanning.
      update_tbl_stats  If true, update table->quick_keys with information
                        about range scan we've evaluated.

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  NOTES
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    param->is_ror_scan is set to reflect if the key scan is a ROR (see
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    is_key_scan_ror function for more info)
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    param->table->quick_*, param->range_count (and maybe others) are
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    updated with data of given key scan, see check_quick_keys for details.
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  RETURN
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    Estimate # of records to be retrieved.
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    HA_POS_ERROR if estimate calculation failed due to table handler problems.
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*/
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static ha_rows
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check_quick_select(PARAM *param,uint idx,SEL_ARG *tree, bool update_tbl_stats)
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{
  ha_rows records;
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  bool    cpk_scan;
  uint key;
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  DBUG_ENTER("check_quick_select");
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  param->is_ror_scan= FALSE;
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  param->first_null_comp= 0;
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  if (!tree)
    DBUG_RETURN(HA_POS_ERROR);			// Can't use it
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  param->max_key_part=0;
  param->range_count=0;
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  key= param->real_keynr[idx];

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  if (tree->type == SEL_ARG::IMPOSSIBLE)
    DBUG_RETURN(0L);				// Impossible select. return
  if (tree->type != SEL_ARG::KEY_RANGE || tree->part != 0)
    DBUG_RETURN(HA_POS_ERROR);				// Don't use tree
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  enum ha_key_alg key_alg= param->table->key_info[key].algorithm;
  if ((key_alg != HA_KEY_ALG_BTREE) && (key_alg!= HA_KEY_ALG_UNDEF))
  {
    /* Records are not ordered by rowid for other types of indexes. */
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    cpk_scan= FALSE;
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  }
  else
  {
    /*
      Clustered PK scan is a special case, check_quick_keys doesn't recognize
      CPK scans as ROR scans (while actually any CPK scan is a ROR scan).
    */
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    cpk_scan= ((param->table->s->primary_key == param->real_keynr[idx]) &&
               param->table->file->primary_key_is_clustered());
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    param->is_ror_scan= !cpk_scan;
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  }
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  param->n_ranges= 0;
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  records= check_quick_keys(param, idx, tree,
                            param->min_key, 0, -1,
                            param->max_key, 0, -1);
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  if (records != HA_POS_ERROR)
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  {
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    if (update_tbl_stats)
    {
      param->table->quick_keys.set_bit(key);
      param->table->quick_key_parts[key]=param->max_key_part+1;
      param->table->quick_n_ranges[key]= param->n_ranges;
      param->table->quick_condition_rows=
        min(param->table->quick_condition_rows, records);
    }
    /*
      Need to save quick_rows in any case as it is used when calculating
      cost of ROR intersection:
    */
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    param->table->quick_rows[key]=records;
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    if (cpk_scan)
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      param->is_ror_scan= TRUE;
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  }
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  if (param->table->file->index_flags(key, 0, TRUE) & HA_KEY_SCAN_NOT_ROR)
    param->is_ror_scan= FALSE;
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  DBUG_PRINT("exit", ("Records: %lu", (ulong) records));
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  DBUG_RETURN(records);
}


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/*
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  Recursively calculate estimate of # rows that will be retrieved by
  key scan on key idx.
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  SYNOPSIS
    check_quick_keys()
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      param         Parameter from test_quick select function.
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      idx           Number of key to use in PARAM::keys in list of used keys
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                    (param->real_keynr[idx] holds the key number in table)
      key_tree      SEL_ARG tree being examined.
      min_key       Buffer with partial min key value tuple
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      min_key_flag
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      max_key       Buffer with partial max key value tuple
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      max_key_flag

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  NOTES
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    The function does the recursive descent on the tree via SEL_ARG::left,
    SEL_ARG::right, and SEL_ARG::next_key_part edges. The #rows estimates
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    are calculated using records_in_range calls at the leaf nodes and then
    summed.
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    param->min_key and param->max_key are used to hold prefixes of key value
    tuples.
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    The side effects are:
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    param->max_key_part is updated to hold the maximum number of key parts used
      in scan minus 1.
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    param->range_count is incremented if the function finds a range that
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      wasn't counted by the caller.
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    param->is_ror_scan is cleared if the function detects that the key scan is
      not a Rowid-Ordered Retrieval scan ( see comments for is_key_scan_ror
      function for description of which key scans are ROR scans)
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  RETURN
    #records      E(#records) for given subtree
    HA_POS_ERROR  if subtree cannot be used for record retrieval

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*/

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static ha_rows
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check_quick_keys(PARAM *param, uint idx, SEL_ARG *key_tree,
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		 uchar *min_key, uint min_key_flag, int min_keypart,
                 uchar *max_key, uint max_key_flag, int max_keypart)
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{
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  ha_rows records=0, tmp;
  uint tmp_min_flag, tmp_max_flag, keynr, min_key_length, max_key_length;
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  uint tmp_min_keypart= min_keypart, tmp_max_keypart= max_keypart;
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  uchar *tmp_min_key, *tmp_max_key;
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  uint8 save_first_null_comp= param->first_null_comp;
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  param->max_key_part=max(param->max_key_part,key_tree->part);
  if (key_tree->left != &null_element)
  {
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    /*
      There are at least two intervals for current key part, i.e. condition
      was converted to something like
        (keyXpartY less/equals c1) OR (keyXpartY more/equals c2).
      This is not a ROR scan if the key is not Clustered Primary Key.
    */
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    param->is_ror_scan= FALSE;
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    records=check_quick_keys(param, idx, key_tree->left,
                             min_key, min_key_flag, min_keypart,
			     max_key, max_key_flag, max_keypart);
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7427 7428 7429 7430
    if (records == HA_POS_ERROR)			// Impossible
      return records;
  }

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  tmp_min_key= min_key;
  tmp_max_key= max_key;
7433 7434 7435 7436 7437 7438
  tmp_min_keypart+= key_tree->store_min(param->key[idx][key_tree->part].store_length,
                                        &tmp_min_key, min_key_flag);
  tmp_max_keypart+= key_tree->store_max(param->key[idx][key_tree->part].store_length,
                                        &tmp_max_key, max_key_flag);
  min_key_length= (uint) (tmp_min_key - param->min_key);
  max_key_length= (uint) (tmp_max_key - param->max_key);
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7439

7440 7441
  if (param->is_ror_scan)
  {
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7442
    /*
7443
      If the index doesn't cover entire key, mark the scan as non-ROR scan.
7444
      Actually we're cutting off some ROR scans here.
7445 7446 7447
    */
    uint16 fieldnr= param->table->key_info[param->real_keynr[idx]].
                    key_part[key_tree->part].fieldnr - 1;
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7448
    if (param->table->field[fieldnr]->key_length() !=
7449
        param->key[idx][key_tree->part].length)
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7450
      param->is_ror_scan= FALSE;
7451 7452
  }

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7453 7454 7455
  if (!param->first_null_comp && key_tree->is_null_interval())
    param->first_null_comp= key_tree->part+1;

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7456 7457 7458 7459 7460
  if (key_tree->next_key_part &&
      key_tree->next_key_part->part == key_tree->part+1 &&
      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
  {						// const key as prefix
    if (min_key_length == max_key_length &&
7461
	!memcmp(min_key, max_key, (uint) (tmp_max_key - max_key)) &&
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7462 7463
	!key_tree->min_flag && !key_tree->max_flag)
    {
7464 7465 7466 7467
      tmp=check_quick_keys(param,idx,key_tree->next_key_part, tmp_min_key,
                           min_key_flag | key_tree->min_flag, tmp_min_keypart,
                           tmp_max_key, max_key_flag | key_tree->max_flag,
                           tmp_max_keypart);
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7468 7469
      goto end;					// Ugly, but efficient
    }
7470
    else
7471 7472
    {
      /* The interval for current key part is not c1 <= keyXpartY <= c1 */
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7473
      param->is_ror_scan= FALSE;
7474
    }
7475

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7476 7477 7478
    tmp_min_flag=key_tree->min_flag;
    tmp_max_flag=key_tree->max_flag;
    if (!tmp_min_flag)
7479
      tmp_min_keypart+=
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7480 7481 7482
      key_tree->next_key_part->store_min_key(param->key[idx], &tmp_min_key,
					     &tmp_min_flag);
    if (!tmp_max_flag)
7483
      tmp_max_keypart+=
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7484 7485
      key_tree->next_key_part->store_max_key(param->key[idx], &tmp_max_key,
					     &tmp_max_flag);
7486 7487
    min_key_length= (uint) (tmp_min_key - param->min_key);
    max_key_length= (uint) (tmp_max_key - param->max_key);
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7488 7489 7490
  }
  else
  {
7491 7492
    tmp_min_flag= min_key_flag | key_tree->min_flag;
    tmp_max_flag= max_key_flag | key_tree->max_flag;
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7493 7494
  }

7495 7496 7497
  if (unlikely(param->thd->killed != 0))
    return HA_POS_ERROR;
  
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7498
  keynr=param->real_keynr[idx];
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7499
  param->range_count++;
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  if (!tmp_min_flag && ! tmp_max_flag &&
      (uint) key_tree->part+1 == param->table->key_info[keynr].key_parts &&
7502
      (param->table->key_info[keynr].flags & (HA_NOSAME | HA_END_SPACE_KEY)) ==
7503
      HA_NOSAME && min_key_length == max_key_length &&
7504
      !memcmp(param->min_key, param->max_key, min_key_length) &&
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7505
      !param->first_null_comp)
7506
  {
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    tmp=1;					// Max one record
7508 7509
    param->n_ranges++;
  }
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7510
  else
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  {
7512 7513
    if (param->is_ror_scan)
    {
7514 7515 7516 7517 7518 7519 7520 7521 7522
      /*
        If we get here, the condition on the key was converted to form
        "(keyXpart1 = c1) AND ... AND (keyXpart{key_tree->part - 1} = cN) AND
          somecond(keyXpart{key_tree->part})"
        Check if
          somecond is "keyXpart{key_tree->part} = const" and
          uncovered "tail" of KeyX parts is either empty or is identical to
          first members of clustered primary key.
      */
7523
      if (!(min_key_length == max_key_length &&
7524
            !memcmp(min_key, max_key, (uint) (tmp_max_key - max_key)) &&
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7525
            !key_tree->min_flag && !key_tree->max_flag &&
7526
            is_key_scan_ror(param, keynr, key_tree->part + 1)))
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        param->is_ror_scan= FALSE;
7528
    }
7529
    param->n_ranges++;
7530

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    if (tmp_min_flag & GEOM_FLAG)
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    {
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7533
      key_range min_range;
7534
      min_range.key=    param->min_key;
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      min_range.length= min_key_length;
7536
      min_range.keypart_map= make_keypart_map(tmp_min_keypart);
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7537 7538 7539
      /* In this case tmp_min_flag contains the handler-read-function */
      min_range.flag=   (ha_rkey_function) (tmp_min_flag ^ GEOM_FLAG);

7540 7541
      tmp= param->table->file->records_in_range(keynr,
                                                &min_range, (key_range*) 0);
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7542 7543 7544
    }
    else
    {
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7545 7546
      key_range min_range, max_range;

7547
      min_range.key=    param->min_key;
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7548 7549 7550
      min_range.length= min_key_length;
      min_range.flag=   (tmp_min_flag & NEAR_MIN ? HA_READ_AFTER_KEY :
                         HA_READ_KEY_EXACT);
7551
      min_range.keypart_map= make_keypart_map(tmp_min_keypart);
7552
      max_range.key=    param->max_key;
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7553 7554 7555
      max_range.length= max_key_length;
      max_range.flag=   (tmp_max_flag & NEAR_MAX ?
                         HA_READ_BEFORE_KEY : HA_READ_AFTER_KEY);
7556
      max_range.keypart_map= make_keypart_map(tmp_max_keypart);
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7557 7558 7559 7560 7561
      tmp=param->table->file->records_in_range(keynr,
                                               (min_key_length ? &min_range :
                                                (key_range*) 0),
                                               (max_key_length ? &max_range :
                                                (key_range*) 0));
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7562 7563
    }
  }
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 end:
  if (tmp == HA_POS_ERROR)			// Impossible range
    return tmp;
  records+=tmp;
  if (key_tree->right != &null_element)
  {
7570 7571 7572 7573 7574 7575
    /*
      There are at least two intervals for current key part, i.e. condition
      was converted to something like
        (keyXpartY less/equals c1) OR (keyXpartY more/equals c2).
      This is not a ROR scan if the key is not Clustered Primary Key.
    */
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7576
    param->is_ror_scan= FALSE;
7577 7578 7579
    tmp=check_quick_keys(param, idx, key_tree->right,
                         min_key, min_key_flag, min_keypart,
                         max_key, max_key_flag, max_keypart);
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7580 7581 7582 7583
    if (tmp == HA_POS_ERROR)
      return tmp;
    records+=tmp;
  }
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7584
  param->first_null_comp= save_first_null_comp;
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7585 7586 7587
  return records;
}

7588

7589
/*
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7590
  Check if key scan on given index with equality conditions on first n key
7591 7592 7593 7594
  parts is a ROR scan.

  SYNOPSIS
    is_key_scan_ror()
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7595
      param  Parameter from test_quick_select
7596 7597 7598 7599
      keynr  Number of key in the table. The key must not be a clustered
             primary key.
      nparts Number of first key parts for which equality conditions
             are present.
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7600

7601 7602 7603
  NOTES
    ROR (Rowid Ordered Retrieval) key scan is a key scan that produces
    ordered sequence of rowids (ha_xxx::cmp_ref is the comparison function)
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7604

7605 7606
    This function is needed to handle a practically-important special case:
    an index scan is a ROR scan if it is done using a condition in form
7607

7608
        "key1_1=c_1 AND ... AND key1_n=c_n"
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7609

7610 7611
    where the index is defined on (key1_1, ..., key1_N [,a_1, ..., a_n])

7612
    and the table has a clustered Primary Key defined as 
7613

7614 7615 7616 7617 7618
      PRIMARY KEY(a_1, ..., a_n, b1, ..., b_k) 
    
    i.e. the first key parts of it are identical to uncovered parts ot the 
    key being scanned. This function assumes that the index flags do not
    include HA_KEY_SCAN_NOT_ROR flag (that is checked elsewhere).
7619

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7620
  RETURN
7621 7622
    TRUE   The scan is ROR-scan
    FALSE  Otherwise
7623
*/
7624

7625 7626 7627 7628
static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts)
{
  KEY *table_key= param->table->key_info + keynr;
  KEY_PART_INFO *key_part= table_key->key_part + nparts;
7629 7630 7631
  KEY_PART_INFO *key_part_end= (table_key->key_part +
                                table_key->key_parts);
  uint pk_number;
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7632

7633
  if (key_part == key_part_end)
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7634
    return TRUE;
7635
  pk_number= param->table->s->primary_key;
7636
  if (!param->table->file->primary_key_is_clustered() || pk_number == MAX_KEY)
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7637
    return FALSE;
7638 7639

  KEY_PART_INFO *pk_part= param->table->key_info[pk_number].key_part;
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  KEY_PART_INFO *pk_part_end= pk_part +
7641
                              param->table->key_info[pk_number].key_parts;
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7642 7643
  for (;(key_part!=key_part_end) && (pk_part != pk_part_end);
       ++key_part, ++pk_part)
7644
  {
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7645
    if ((key_part->field != pk_part->field) ||
7646
        (key_part->length != pk_part->length))
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7647
      return FALSE;
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7648
  }
7649
  return (key_part == key_part_end);
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7650 7651 7652
}


7653 7654
/*
  Create a QUICK_RANGE_SELECT from given key and SEL_ARG tree for that key.
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7655

7656 7657
  SYNOPSIS
    get_quick_select()
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7658
      param
7659
      idx          Index of used key in param->key.
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7660 7661
      key_tree     SEL_ARG tree for the used key
      parent_alloc If not NULL, use it to allocate memory for
7662
                   quick select data. Otherwise use quick->alloc.
7663
  NOTES
7664
    The caller must call QUICK_SELECT::init for returned quick select
7665

7666
    CAUTION! This function may change thd->mem_root to a MEM_ROOT which will be
7667
    deallocated when the returned quick select is deleted.
7668 7669 7670 7671

  RETURN
    NULL on error
    otherwise created quick select
7672
*/
7673

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7674 7675 7676
QUICK_RANGE_SELECT *
get_quick_select(PARAM *param,uint idx,SEL_ARG *key_tree,
                 MEM_ROOT *parent_alloc)
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7677
{
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7678
  QUICK_RANGE_SELECT *quick;
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7679
  DBUG_ENTER("get_quick_select");
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7680 7681 7682 7683 7684 7685 7686 7687 7688

  if (param->table->key_info[param->real_keynr[idx]].flags & HA_SPATIAL)
    quick=new QUICK_RANGE_SELECT_GEOM(param->thd, param->table,
                                      param->real_keynr[idx],
                                      test(parent_alloc),
                                      parent_alloc);
  else
    quick=new QUICK_RANGE_SELECT(param->thd, param->table,
                                 param->real_keynr[idx],
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7689
                                 test(parent_alloc));
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7690

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7691
  if (quick)
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7692 7693 7694 7695 7696 7697 7698 7699 7700 7701 7702
  {
    if (quick->error ||
	get_quick_keys(param,quick,param->key[idx],key_tree,param->min_key,0,
		       param->max_key,0))
    {
      delete quick;
      quick=0;
    }
    else
    {
      quick->key_parts=(KEY_PART*)
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7703 7704 7705 7706
        memdup_root(parent_alloc? parent_alloc : &quick->alloc,
                    (char*) param->key[idx],
                    sizeof(KEY_PART)*
                    param->table->key_info[param->real_keynr[idx]].key_parts);
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7707
    }
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7708
  }
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  DBUG_RETURN(quick);
}


/*
** Fix this to get all possible sub_ranges
*/
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7716 7717
bool
get_quick_keys(PARAM *param,QUICK_RANGE_SELECT *quick,KEY_PART *key,
7718 7719
	       SEL_ARG *key_tree, uchar *min_key,uint min_key_flag,
	       uchar *max_key, uint max_key_flag)
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{
  QUICK_RANGE *range;
  uint flag;
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7723 7724
  int min_part= key_tree->part-1, // # of keypart values in min_key buffer
      max_part= key_tree->part-1; // # of keypart values in max_key buffer
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7725 7726 7727 7728 7729 7730 7731

  if (key_tree->left != &null_element)
  {
    if (get_quick_keys(param,quick,key,key_tree->left,
		       min_key,min_key_flag, max_key, max_key_flag))
      return 1;
  }
7732
  uchar *tmp_min_key=min_key,*tmp_max_key=max_key;
7733 7734 7735 7736
  min_part+= key_tree->store_min(key[key_tree->part].store_length,
                                 &tmp_min_key,min_key_flag);
  max_part+= key_tree->store_max(key[key_tree->part].store_length,
                                 &tmp_max_key,max_key_flag);
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7737 7738 7739 7740 7741

  if (key_tree->next_key_part &&
      key_tree->next_key_part->part == key_tree->part+1 &&
      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
  {						  // const key as prefix
7742 7743 7744
    if ((tmp_min_key - min_key) == (tmp_max_key - max_key) &&
         memcmp(min_key, max_key, (uint)(tmp_max_key - max_key))==0 &&
	 key_tree->min_flag==0 && key_tree->max_flag==0)
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7745 7746 7747 7748 7749 7750 7751 7752 7753 7754
    {
      if (get_quick_keys(param,quick,key,key_tree->next_key_part,
			 tmp_min_key, min_key_flag | key_tree->min_flag,
			 tmp_max_key, max_key_flag | key_tree->max_flag))
	return 1;
      goto end;					// Ugly, but efficient
    }
    {
      uint tmp_min_flag=key_tree->min_flag,tmp_max_flag=key_tree->max_flag;
      if (!tmp_min_flag)
7755
        min_part+= key_tree->next_key_part->store_min_key(key, &tmp_min_key,
7756
                                                          &tmp_min_flag);
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7757
      if (!tmp_max_flag)
7758
        max_part+= key_tree->next_key_part->store_max_key(key, &tmp_max_key,
7759
                                                          &tmp_max_flag);
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7760 7761 7762 7763
      flag=tmp_min_flag | tmp_max_flag;
    }
  }
  else
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  {
    flag = (key_tree->min_flag & GEOM_FLAG) ?
      key_tree->min_flag : key_tree->min_flag | key_tree->max_flag;
  }
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7769 7770 7771 7772 7773
  /*
    Ensure that some part of min_key and max_key are used.  If not,
    regard this as no lower/upper range
  */
  if ((flag & GEOM_FLAG) == 0)
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7774 7775 7776 7777 7778 7779 7780 7781 7782 7783
  {
    if (tmp_min_key != param->min_key)
      flag&= ~NO_MIN_RANGE;
    else
      flag|= NO_MIN_RANGE;
    if (tmp_max_key != param->max_key)
      flag&= ~NO_MAX_RANGE;
    else
      flag|= NO_MAX_RANGE;
  }
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7784 7785 7786 7787 7788 7789 7790 7791
  if (flag == 0)
  {
    uint length= (uint) (tmp_min_key - param->min_key);
    if (length == (uint) (tmp_max_key - param->max_key) &&
	!memcmp(param->min_key,param->max_key,length))
    {
      KEY *table_key=quick->head->key_info+quick->index;
      flag=EQ_RANGE;
7792 7793
      if ((table_key->flags & (HA_NOSAME | HA_END_SPACE_KEY)) == HA_NOSAME &&
	  key->part == table_key->key_parts-1)
7794 7795 7796 7797 7798 7799 7800 7801 7802
      {
	if (!(table_key->flags & HA_NULL_PART_KEY) ||
	    !null_part_in_key(key,
			      param->min_key,
			      (uint) (tmp_min_key - param->min_key)))
	  flag|= UNIQUE_RANGE;
	else
	  flag|= NULL_RANGE;
      }
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7803 7804 7805 7806
    }
  }

  /* Get range for retrieving rows in QUICK_SELECT::get_next */
7807
  if (!(range= new QUICK_RANGE(param->min_key,
7808
			       (uint) (tmp_min_key - param->min_key),
7809
                               min_part >=0 ? make_keypart_map(min_part) : 0,
7810
			       param->max_key,
7811
			       (uint) (tmp_max_key - param->max_key),
7812
                               max_part >=0 ? make_keypart_map(max_part) : 0,
7813
			       flag)))
7814 7815
    return 1;			// out of memory

7816 7817
  set_if_bigger(quick->max_used_key_length, range->min_length);
  set_if_bigger(quick->max_used_key_length, range->max_length);
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7818
  set_if_bigger(quick->used_key_parts, (uint) key_tree->part+1);
7819
  if (insert_dynamic(&quick->ranges, (uchar*) &range))
7820 7821
    return 1;

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 end:
  if (key_tree->right != &null_element)
    return get_quick_keys(param,quick,key,key_tree->right,
			  min_key,min_key_flag,
			  max_key,max_key_flag);
  return 0;
}

/*
  Return 1 if there is only one range and this uses the whole primary key
*/

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7834
bool QUICK_RANGE_SELECT::unique_key_range()
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{
  if (ranges.elements == 1)
  {
7838 7839
    QUICK_RANGE *tmp= *((QUICK_RANGE**)ranges.buffer);
    if ((tmp->flag & (EQ_RANGE | NULL_RANGE)) == EQ_RANGE)
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7840 7841
    {
      KEY *key=head->key_info+index;
7842
      return ((key->flags & (HA_NOSAME | HA_END_SPACE_KEY)) == HA_NOSAME &&
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7843 7844 7845 7846 7847 7848
	      key->key_length == tmp->min_length);
    }
  }
  return 0;
}

7849

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7850
/* Returns TRUE if any part of the key is NULL */
7851

7852
static bool null_part_in_key(KEY_PART *key_part, const uchar *key, uint length)
7853
{
7854
  for (const uchar *end=key+length ;
7855
       key < end;
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7856
       key+= key_part++->store_length)
7857
  {
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7858 7859
    if (key_part->null_bit && *key)
      return 1;
7860 7861 7862 7863
  }
  return 0;
}

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7864

7865
bool QUICK_SELECT_I::is_keys_used(const MY_BITMAP *fields)
7866
{
7867
  return is_key_used(head, index, fields);
7868 7869
}

7870
bool QUICK_INDEX_MERGE_SELECT::is_keys_used(const MY_BITMAP *fields)
7871 7872 7873 7874 7875
{
  QUICK_RANGE_SELECT *quick;
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  while ((quick= it++))
  {
7876
    if (is_key_used(head, quick->index, fields))
7877 7878 7879 7880 7881
      return 1;
  }
  return 0;
}

7882
bool QUICK_ROR_INTERSECT_SELECT::is_keys_used(const MY_BITMAP *fields)
7883 7884 7885 7886 7887
{
  QUICK_RANGE_SELECT *quick;
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  while ((quick= it++))
  {
7888
    if (is_key_used(head, quick->index, fields))
7889 7890 7891 7892 7893
      return 1;
  }
  return 0;
}

7894
bool QUICK_ROR_UNION_SELECT::is_keys_used(const MY_BITMAP *fields)
7895 7896 7897 7898 7899
{
  QUICK_SELECT_I *quick;
  List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
  while ((quick= it++))
  {
7900
    if (quick->is_keys_used(fields))
7901 7902 7903 7904 7905
      return 1;
  }
  return 0;
}

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7906

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7907 7908
/*
  Create quick select from ref/ref_or_null scan.
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7909

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7910 7911 7912 7913 7914
  SYNOPSIS
    get_quick_select_for_ref()
      thd      Thread handle
      table    Table to access
      ref      ref[_or_null] scan parameters
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7915
      records  Estimate of number of records (needed only to construct
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7916 7917 7918 7919
               quick select)
  NOTES
    This allocates things in a new memory root, as this may be called many
    times during a query.
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7920 7921

  RETURN
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7922 7923 7924
    Quick select that retrieves the same rows as passed ref scan
    NULL on error.
*/
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7925

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7926
QUICK_RANGE_SELECT *get_quick_select_for_ref(THD *thd, TABLE *table,
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7927
                                             TABLE_REF *ref, ha_rows records)
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7928
{
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7929 7930
  MEM_ROOT *old_root, *alloc;
  QUICK_RANGE_SELECT *quick;
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7931 7932
  KEY *key_info = &table->key_info[ref->key];
  KEY_PART *key_part;
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7933
  QUICK_RANGE *range;
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7934
  uint part;
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7935 7936 7937 7938 7939 7940

  old_root= thd->mem_root;
  /* The following call may change thd->mem_root */
  quick= new QUICK_RANGE_SELECT(thd, table, ref->key, 0);
  /* save mem_root set by QUICK_RANGE_SELECT constructor */
  alloc= thd->mem_root;
7941 7942 7943 7944 7945
  /*
    return back default mem_root (thd->mem_root) changed by
    QUICK_RANGE_SELECT constructor
  */
  thd->mem_root= old_root;
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7946 7947

  if (!quick)
7948
    return 0;			/* no ranges found */
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7949
  if (quick->init())
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7950
    goto err;
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7951
  quick->records= records;
7952

7953
  if (cp_buffer_from_ref(thd, table, ref) && thd->is_fatal_error ||
7954
      !(range= new(alloc) QUICK_RANGE()))
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7955
    goto err;                                   // out of memory
7956

7957
  range->min_key= range->max_key= ref->key_buff;
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7958 7959 7960
  range->min_length= range->max_length= ref->key_length;
  range->min_keypart_map= range->max_keypart_map=
    make_prev_keypart_map(ref->key_parts);
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7961
  range->flag= ((ref->key_length == key_info->key_length &&
7962
		 (key_info->flags & HA_END_SPACE_KEY) == 0) ? EQ_RANGE : 0);
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7963 7964

  if (!(quick->key_parts=key_part=(KEY_PART *)
7965
	alloc_root(&quick->alloc,sizeof(KEY_PART)*ref->key_parts)))
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7966 7967 7968 7969 7970 7971
    goto err;

  for (part=0 ; part < ref->key_parts ;part++,key_part++)
  {
    key_part->part=part;
    key_part->field=        key_info->key_part[part].field;
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7972
    key_part->length=       key_info->key_part[part].length;
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7973
    key_part->store_length= key_info->key_part[part].store_length;
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7974
    key_part->null_bit=     key_info->key_part[part].null_bit;
7975
    key_part->flag=         (uint8) key_info->key_part[part].key_part_flag;
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7976
  }
7977
  if (insert_dynamic(&quick->ranges,(uchar*)&range))
7978 7979
    goto err;

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7980
  /*
7981 7982 7983 7984 7985
     Add a NULL range if REF_OR_NULL optimization is used.
     For example:
       if we have "WHERE A=2 OR A IS NULL" we created the (A=2) range above
       and have ref->null_ref_key set. Will create a new NULL range here.
  */
7986 7987 7988 7989 7990
  if (ref->null_ref_key)
  {
    QUICK_RANGE *null_range;

    *ref->null_ref_key= 1;		// Set null byte then create a range
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7991
    if (!(null_range= new (alloc)
7992
          QUICK_RANGE(ref->key_buff, ref->key_length,
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7993
                      make_prev_keypart_map(ref->key_parts),
7994
                      ref->key_buff, ref->key_length,
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7995
                      make_prev_keypart_map(ref->key_parts), EQ_RANGE)))
7996 7997
      goto err;
    *ref->null_ref_key= 0;		// Clear null byte
7998
    if (insert_dynamic(&quick->ranges,(uchar*)&null_range))
7999 8000 8001 8002
      goto err;
  }

  return quick;
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8003 8004 8005 8006 8007 8008

err:
  delete quick;
  return 0;
}

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8009 8010

/*
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  Perform key scans for all used indexes (except CPK), get rowids and merge 
  them into an ordered non-recurrent sequence of rowids.
  
  The merge/duplicate removal is performed using Unique class. We put all
  rowids into Unique, get the sorted sequence and destroy the Unique.
  
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  If table has a clustered primary key that covers all rows (TRUE for bdb
8018 8019 8020
  and innodb currently) and one of the index_merge scans is a scan on PK,
  then rows that will be retrieved by PK scan are not put into Unique and 
  primary key scan is not performed here, it is performed later separately.
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8021

8022 8023 8024
  RETURN
    0     OK
    other error
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8025
*/
8026

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8027
int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
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{
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  List_iterator_fast<QUICK_RANGE_SELECT> cur_quick_it(quick_selects);
  QUICK_RANGE_SELECT* cur_quick;
8031
  int result;
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8032
  Unique *unique;
8033 8034
  handler *file= head->file;
  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::read_keys_and_merge");
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8035

8036
  /* We're going to just read rowids. */
8037 8038
  file->extra(HA_EXTRA_KEYREAD);
  head->prepare_for_position();
8039

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8040 8041
  cur_quick_it.rewind();
  cur_quick= cur_quick_it++;
8042
  DBUG_ASSERT(cur_quick != 0);
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8043 8044 8045 8046 8047
  
  /*
    We reuse the same instance of handler so we need to call both init and 
    reset here.
  */
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8048
  if (cur_quick->init() || cur_quick->reset())
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8049
    DBUG_RETURN(1);
8050

8051 8052
  unique= new Unique(refpos_order_cmp, (void *)file,
                     file->ref_length,
8053
                     thd->variables.sortbuff_size);
8054 8055
  if (!unique)
    DBUG_RETURN(1);
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8056
  for (;;)
8057
  {
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8058
    while ((result= cur_quick->get_next()) == HA_ERR_END_OF_FILE)
8059
    {
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8060 8061 8062
      cur_quick->range_end();
      cur_quick= cur_quick_it++;
      if (!cur_quick)
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8063
        break;
8064

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8065 8066
      if (cur_quick->file->inited != handler::NONE) 
        cur_quick->file->ha_index_end();
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8067
      if (cur_quick->init() || cur_quick->reset())
8068
        DBUG_RETURN(1);
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8069 8070 8071
    }

    if (result)
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8072
    {
8073
      if (result != HA_ERR_END_OF_FILE)
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8074 8075
      {
        cur_quick->range_end();
8076
        DBUG_RETURN(result);
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8077
      }
8078
      break;
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8079
    }
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8080

8081 8082
    if (thd->killed)
      DBUG_RETURN(1);
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8083

8084
    /* skip row if it will be retrieved by clustered PK scan */
8085 8086
    if (pk_quick_select && pk_quick_select->row_in_ranges())
      continue;
8087

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8088 8089
    cur_quick->file->position(cur_quick->record);
    result= unique->unique_add((char*)cur_quick->file->ref);
8090
    if (result)
8091 8092
      DBUG_RETURN(1);

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8093
  }
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8094

8095 8096 8097 8098 8099
  /*
    Ok all rowids are in the Unique now. The next call will initialize
    head->sort structure so it can be used to iterate through the rowids
    sequence.
  */
8100
  result= unique->get(head);
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8101
  delete unique;
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8102
  doing_pk_scan= FALSE;
8103 8104
  /* index_merge currently doesn't support "using index" at all */
  file->extra(HA_EXTRA_NO_KEYREAD);
8105
  init_read_record(&read_record, thd, head, (SQL_SELECT*) 0, 1 , 1, TRUE);
8106 8107 8108
  DBUG_RETURN(result);
}

8109

8110 8111 8112
/*
  Get next row for index_merge.
  NOTES
8113 8114 8115 8116
    The rows are read from
      1. rowids stored in Unique.
      2. QUICK_RANGE_SELECT with clustered primary key (if any).
    The sets of rows retrieved in 1) and 2) are guaranteed to be disjoint.
8117
*/
8118

8119 8120
int QUICK_INDEX_MERGE_SELECT::get_next()
{
8121
  int result;
8122
  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::get_next");
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8123

8124 8125 8126
  if (doing_pk_scan)
    DBUG_RETURN(pk_quick_select->get_next());

8127
  if ((result= read_record.read_record(&read_record)) == -1)
8128 8129 8130
  {
    result= HA_ERR_END_OF_FILE;
    end_read_record(&read_record);
8131
    free_io_cache(head);
8132
    /* All rows from Unique have been retrieved, do a clustered PK scan */
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8133
    if (pk_quick_select)
8134
    {
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8135
      doing_pk_scan= TRUE;
8136 8137
      if ((result= pk_quick_select->init()) ||
          (result= pk_quick_select->reset()))
8138 8139 8140 8141 8142 8143
        DBUG_RETURN(result);
      DBUG_RETURN(pk_quick_select->get_next());
    }
  }

  DBUG_RETURN(result);
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8144 8145
}

8146 8147

/*
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8148
  Retrieve next record.
8149
  SYNOPSIS
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8150 8151
     QUICK_ROR_INTERSECT_SELECT::get_next()

8152
  NOTES
8153 8154
    Invariant on enter/exit: all intersected selects have retrieved all index
    records with rowid <= some_rowid_val and no intersected select has
8155 8156 8157 8158
    retrieved any index records with rowid > some_rowid_val.
    We start fresh and loop until we have retrieved the same rowid in each of
    the key scans or we got an error.

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8159
    If a Clustered PK scan is present, it is used only to check if row
8160 8161 8162 8163 8164
    satisfies its condition (and never used for row retrieval).

  RETURN
   0     - Ok
   other - Error code if any error occurred.
8165 8166 8167 8168 8169 8170 8171 8172 8173
*/

int QUICK_ROR_INTERSECT_SELECT::get_next()
{
  List_iterator_fast<QUICK_RANGE_SELECT> quick_it(quick_selects);
  QUICK_RANGE_SELECT* quick;
  int error, cmp;
  uint last_rowid_count=0;
  DBUG_ENTER("QUICK_ROR_INTERSECT_SELECT::get_next");
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8174

8175
  do
8176
  {
8177 8178
    /* Get a rowid for first quick and save it as a 'candidate' */
    quick= quick_it++;
8179
    error= quick->get_next();
8180 8181
    if (cpk_quick)
    {
8182
      while (!error && !cpk_quick->row_in_ranges())
8183 8184 8185 8186
        error= quick->get_next();
    }
    if (error)
      DBUG_RETURN(error);
8187

8188 8189 8190
    quick->file->position(quick->record);
    memcpy(last_rowid, quick->file->ref, head->file->ref_length);
    last_rowid_count= 1;
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8191

8192
    while (last_rowid_count < quick_selects.elements)
8193
    {
8194 8195 8196 8197 8198
      if (!(quick= quick_it++))
      {
        quick_it.rewind();
        quick= quick_it++;
      }
8199

8200 8201 8202 8203 8204 8205 8206 8207 8208 8209
      do
      {
        if ((error= quick->get_next()))
          DBUG_RETURN(error);
        quick->file->position(quick->record);
        cmp= head->file->cmp_ref(quick->file->ref, last_rowid);
      } while (cmp < 0);

      /* Ok, current select 'caught up' and returned ref >= cur_ref */
      if (cmp > 0)
8210
      {
8211 8212
        /* Found a row with ref > cur_ref. Make it a new 'candidate' */
        if (cpk_quick)
8213
        {
8214 8215 8216 8217 8218
          while (!cpk_quick->row_in_ranges())
          {
            if ((error= quick->get_next()))
              DBUG_RETURN(error);
          }
8219
        }
8220 8221 8222 8223 8224 8225 8226
        memcpy(last_rowid, quick->file->ref, head->file->ref_length);
        last_rowid_count= 1;
      }
      else
      {
        /* current 'candidate' row confirmed by this select */
        last_rowid_count++;
8227 8228 8229
      }
    }

8230
    /* We get here if we got the same row ref in all scans. */
8231 8232 8233
    if (need_to_fetch_row)
      error= head->file->rnd_pos(head->record[0], last_rowid);
  } while (error == HA_ERR_RECORD_DELETED);
8234 8235 8236 8237
  DBUG_RETURN(error);
}


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8238 8239
/*
  Retrieve next record.
8240 8241
  SYNOPSIS
    QUICK_ROR_UNION_SELECT::get_next()
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8242

8243
  NOTES
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8244 8245
    Enter/exit invariant:
    For each quick select in the queue a {key,rowid} tuple has been
8246
    retrieved but the corresponding row hasn't been passed to output.
8247

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8248
  RETURN
8249 8250
   0     - Ok
   other - Error code if any error occurred.
8251 8252 8253 8254 8255 8256
*/

int QUICK_ROR_UNION_SELECT::get_next()
{
  int error, dup_row;
  QUICK_SELECT_I *quick;
8257
  uchar *tmp;
8258
  DBUG_ENTER("QUICK_ROR_UNION_SELECT::get_next");
unknown's avatar
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8259

8260 8261
  do
  {
8262 8263 8264 8265 8266
    do
    {
      if (!queue.elements)
        DBUG_RETURN(HA_ERR_END_OF_FILE);
      /* Ok, we have a queue with >= 1 scans */
8267

8268 8269
      quick= (QUICK_SELECT_I*)queue_top(&queue);
      memcpy(cur_rowid, quick->last_rowid, rowid_length);
8270

8271 8272 8273 8274 8275 8276 8277 8278 8279 8280 8281 8282
      /* put into queue rowid from the same stream as top element */
      if ((error= quick->get_next()))
      {
        if (error != HA_ERR_END_OF_FILE)
          DBUG_RETURN(error);
        queue_remove(&queue, 0);
      }
      else
      {
        quick->save_last_pos();
        queue_replaced(&queue);
      }
unknown's avatar
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8283

8284 8285 8286 8287 8288 8289 8290 8291 8292
      if (!have_prev_rowid)
      {
        /* No rows have been returned yet */
        dup_row= FALSE;
        have_prev_rowid= TRUE;
      }
      else
        dup_row= !head->file->cmp_ref(cur_rowid, prev_rowid);
    } while (dup_row);
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8293

8294 8295 8296
    tmp= cur_rowid;
    cur_rowid= prev_rowid;
    prev_rowid= tmp;
8297

8298 8299
    error= head->file->rnd_pos(quick->record, prev_rowid);
  } while (error == HA_ERR_RECORD_DELETED);
8300 8301 8302
  DBUG_RETURN(error);
}

8303

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8304
int QUICK_RANGE_SELECT::reset()
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8305 8306
{
  uint  mrange_bufsiz;
8307
  uchar *mrange_buff;
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8308 8309
  DBUG_ENTER("QUICK_RANGE_SELECT::reset");
  next=0;
8310
  last_range= NULL;
8311
  in_range= FALSE;
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8312
  cur_range= (QUICK_RANGE**) ranges.buffer;
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8313

8314
  if (file->inited == handler::NONE && (error= file->ha_index_init(index,1)))
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8315
    DBUG_RETURN(error);
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8316
 
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8317 8318 8319 8320 8321 8322 8323
  /* Do not allocate the buffers twice. */
  if (multi_range_length)
  {
    DBUG_ASSERT(multi_range_length == min(multi_range_count, ranges.elements));
    DBUG_RETURN(0);
  }

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8324 8325
  /* Allocate the ranges array. */
  DBUG_ASSERT(ranges.elements);
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8326 8327 8328 8329 8330 8331 8332 8333 8334 8335 8336 8337 8338 8339 8340 8341
  multi_range_length= min(multi_range_count, ranges.elements);
  DBUG_ASSERT(multi_range_length > 0);
  while (multi_range_length && ! (multi_range= (KEY_MULTI_RANGE*)
                                  my_malloc(multi_range_length *
                                            sizeof(KEY_MULTI_RANGE),
                                            MYF(MY_WME))))
  {
    /* Try to shrink the buffers until it is 0. */
    multi_range_length/= 2;
  }
  if (! multi_range)
  {
    multi_range_length= 0;
    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
  }

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8342
  /* Allocate the handler buffer if necessary.  */
8343
  if (file->ha_table_flags() & HA_NEED_READ_RANGE_BUFFER)
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8344 8345
  {
    mrange_bufsiz= min(multi_range_bufsiz,
8346
                       ((uint)QUICK_SELECT_I::records + 1)* head->s->reclength);
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8347 8348 8349

    while (mrange_bufsiz &&
           ! my_multi_malloc(MYF(MY_WME),
8350 8351 8352
                             &multi_range_buff,
                             (uint) sizeof(*multi_range_buff),
                             &mrange_buff, (uint) mrange_bufsiz,
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8353 8354 8355 8356 8357 8358 8359 8360 8361 8362 8363 8364 8365 8366 8367 8368 8369
                             NullS))
    {
      /* Try to shrink the buffers until both are 0. */
      mrange_bufsiz/= 2;
    }
    if (! multi_range_buff)
    {
      my_free((char*) multi_range, MYF(0));
      multi_range= NULL;
      multi_range_length= 0;
      DBUG_RETURN(HA_ERR_OUT_OF_MEM);
    }

    /* Initialize the handler buffer. */
    multi_range_buff->buffer= mrange_buff;
    multi_range_buff->buffer_end= mrange_buff + mrange_bufsiz;
    multi_range_buff->end_of_used_area= mrange_buff;
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8370 8371 8372 8373 8374 8375 8376 8377
#ifdef HAVE_purify
    /*
      We need this until ndb will use the buffer efficiently
      (Now ndb stores  complete row in here, instead of only the used fields
      which gives us valgrind warnings in compare_record[])
    */
    bzero((char*) mrange_buff, mrange_bufsiz);
#endif
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8378 8379 8380 8381 8382 8383 8384 8385 8386 8387 8388 8389 8390 8391 8392 8393 8394 8395 8396
  }
  DBUG_RETURN(0);
}


/*
  Get next possible record using quick-struct.

  SYNOPSIS
    QUICK_RANGE_SELECT::get_next()

  NOTES
    Record is read into table->record[0]

  RETURN
    0			Found row
    HA_ERR_END_OF_FILE	No (more) rows in range
    #			Error code
*/
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8397

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8398
int QUICK_RANGE_SELECT::get_next()
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8399
{
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8400 8401 8402 8403
  int             result;
  KEY_MULTI_RANGE *mrange;
  key_range       *start_key;
  key_range       *end_key;
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8404
  DBUG_ENTER("QUICK_RANGE_SELECT::get_next");
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8405 8406 8407
  DBUG_ASSERT(multi_range_length && multi_range &&
              (cur_range >= (QUICK_RANGE**) ranges.buffer) &&
              (cur_range <= (QUICK_RANGE**) ranges.buffer + ranges.elements));
unknown's avatar
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8408

8409 8410 8411 8412 8413 8414 8415 8416 8417
  if (in_ror_merged_scan)
  {
    /*
      We don't need to signal the bitmap change as the bitmap is always the
      same for this head->file
    */
    head->column_bitmaps_set_no_signal(&column_bitmap, &column_bitmap);
  }

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8418 8419
  for (;;)
  {
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8420
    if (in_range)
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8421
    {
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8422 8423
      /* We did already start to read this key. */
      result= file->read_multi_range_next(&mrange);
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8424
      if (result != HA_ERR_END_OF_FILE)
8425
        goto end;
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8426
    }
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8427

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8428 8429 8430 8431 8432 8433
    uint count= min(multi_range_length, ranges.elements -
                    (cur_range - (QUICK_RANGE**) ranges.buffer));
    if (count == 0)
    {
      /* Ranges have already been used up before. None is left for read. */
      in_range= FALSE;
8434 8435
      if (in_ror_merged_scan)
        head->column_bitmaps_set_no_signal(save_read_set, save_write_set);
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8436 8437 8438 8439 8440 8441 8442 8443 8444
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
    KEY_MULTI_RANGE *mrange_slot, *mrange_end;
    for (mrange_slot= multi_range, mrange_end= mrange_slot+count;
         mrange_slot < mrange_end;
         mrange_slot++)
    {
      start_key= &mrange_slot->start_key;
      end_key= &mrange_slot->end_key;
8445
      last_range= *(cur_range++);
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8446

8447
      start_key->key=    (const uchar*) last_range->min_key;
8448 8449 8450
      start_key->length= last_range->min_length;
      start_key->flag=   ((last_range->flag & NEAR_MIN) ? HA_READ_AFTER_KEY :
                          (last_range->flag & EQ_RANGE) ?
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8451
                          HA_READ_KEY_EXACT : HA_READ_KEY_OR_NEXT);
8452
      start_key->keypart_map= last_range->min_keypart_map;
8453
      end_key->key=      (const uchar*) last_range->max_key;
8454
      end_key->length=   last_range->max_length;
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8455 8456 8457 8458
      /*
        We use HA_READ_AFTER_KEY here because if we are reading on a key
        prefix. We want to find all keys with this prefix.
      */
8459
      end_key->flag=     (last_range->flag & NEAR_MAX ? HA_READ_BEFORE_KEY :
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                          HA_READ_AFTER_KEY);
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      end_key->keypart_map= last_range->max_keypart_map;
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8462

8463
      mrange_slot->range_flag= last_range->flag;
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8464
    }
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8465

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    result= file->read_multi_range_first(&mrange, multi_range, count,
                                         sorted, multi_range_buff);
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    if (result != HA_ERR_END_OF_FILE)
8469
      goto end;
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    in_range= FALSE; /* No matching rows; go to next set of ranges. */
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8471
  }
8472 8473 8474 8475 8476 8477 8478 8479 8480

end:
  in_range= ! result;
  if (in_ror_merged_scan)
  {
    /* Restore bitmaps set on entry */
    head->column_bitmaps_set_no_signal(save_read_set, save_write_set);
  }
  DBUG_RETURN(result);
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}

8483 8484 8485 8486 8487 8488
/*
  Get the next record with a different prefix.

  SYNOPSIS
    QUICK_RANGE_SELECT::get_next_prefix()
    prefix_length  length of cur_prefix
8489
    cur_prefix     prefix of a key to be searched for
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  DESCRIPTION
    Each subsequent call to the method retrieves the first record that has a
    prefix with length prefix_length different from cur_prefix, such that the
    record with the new prefix is within the ranges described by
    this->ranges. The record found is stored into the buffer pointed by
    this->record.
    The method is useful for GROUP-BY queries with range conditions to
    discover the prefix of the next group that satisfies the range conditions.

  TODO
    This method is a modified copy of QUICK_RANGE_SELECT::get_next(), so both
    methods should be unified into a more general one to reduce code
    duplication.

  RETURN
    0                  on success
    HA_ERR_END_OF_FILE if returned all keys
    other              if some error occurred
*/

8511
int QUICK_RANGE_SELECT::get_next_prefix(uint prefix_length,
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                                        key_part_map keypart_map,
8513
                                        uchar *cur_prefix)
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{
  DBUG_ENTER("QUICK_RANGE_SELECT::get_next_prefix");

  for (;;)
  {
    int result;
    key_range start_key, end_key;
8521
    if (last_range)
8522 8523
    {
      /* Read the next record in the same range with prefix after cur_prefix. */
8524
      DBUG_ASSERT(cur_prefix != 0);
8525 8526
      result= file->index_read_map(record, cur_prefix, keypart_map,
                                   HA_READ_AFTER_KEY);
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      if (result || (file->compare_key(file->end_range) <= 0))
        DBUG_RETURN(result);
    }

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    uint count= ranges.elements - (cur_range - (QUICK_RANGE**) ranges.buffer);
    if (count == 0)
    {
      /* Ranges have already been used up before. None is left for read. */
8535
      last_range= 0;
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      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
8538
    last_range= *(cur_range++);
8539

8540
    start_key.key=    (const uchar*) last_range->min_key;
8541
    start_key.length= min(last_range->min_length, prefix_length);
8542
    start_key.keypart_map= last_range->min_keypart_map & keypart_map;
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    start_key.flag=   ((last_range->flag & NEAR_MIN) ? HA_READ_AFTER_KEY :
		       (last_range->flag & EQ_RANGE) ?
8545
		       HA_READ_KEY_EXACT : HA_READ_KEY_OR_NEXT);
8546
    end_key.key=      (const uchar*) last_range->max_key;
8547
    end_key.length=   min(last_range->max_length, prefix_length);
8548
    end_key.keypart_map= last_range->max_keypart_map & keypart_map;
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    /*
      We use READ_AFTER_KEY here because if we are reading on a key
      prefix we want to find all keys with this prefix
    */
8553
    end_key.flag=     (last_range->flag & NEAR_MAX ? HA_READ_BEFORE_KEY :
8554 8555
		       HA_READ_AFTER_KEY);

8556 8557
    result= file->read_range_first(last_range->min_keypart_map ? &start_key : 0,
				   last_range->max_keypart_map ? &end_key : 0,
8558
                                   test(last_range->flag & EQ_RANGE),
8559
				   TRUE);
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    if (last_range->flag == (UNIQUE_RANGE | EQ_RANGE))
      last_range= 0;			// Stop searching
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    if (result != HA_ERR_END_OF_FILE)
      DBUG_RETURN(result);
8565
    last_range= 0;			// No matching rows; go to next range
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  }
}


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8570
/* Get next for geometrical indexes */
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8571

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int QUICK_RANGE_SELECT_GEOM::get_next()
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{
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  DBUG_ENTER("QUICK_RANGE_SELECT_GEOM::get_next");
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8575

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  for (;;)
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  {
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    int result;
8579
    if (last_range)
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    {
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      // Already read through key
8582
      result= file->index_next_same(record, last_range->min_key,
8583
				    last_range->min_length);
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      if (result != HA_ERR_END_OF_FILE)
	DBUG_RETURN(result);
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    }
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    uint count= ranges.elements - (cur_range - (QUICK_RANGE**) ranges.buffer);
    if (count == 0)
    {
      /* Ranges have already been used up before. None is left for read. */
8592
      last_range= 0;
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      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
8595
    last_range= *(cur_range++);
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8596

8597 8598 8599 8600
    result= file->index_read_map(record, last_range->min_key,
                                 last_range->min_keypart_map,
                                 (ha_rkey_function)(last_range->flag ^
                                                    GEOM_FLAG));
8601
    if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE)
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8602
      DBUG_RETURN(result);
8603
    last_range= 0;				// Not found, to next range
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  }
}

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8608 8609 8610 8611
/*
  Check if current row will be retrieved by this QUICK_RANGE_SELECT

  NOTES
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    It is assumed that currently a scan is being done on another index
    which reads all necessary parts of the index that is scanned by this
8614
    quick select.
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    The implementation does a binary search on sorted array of disjoint
8616 8617
    ranges, without taking size of range into account.

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    This function is used to filter out clustered PK scan rows in
8619 8620
    index_merge quick select.

8621
  RETURN
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    TRUE  if current row will be retrieved by this quick select
    FALSE if not
8624 8625 8626 8627
*/

bool QUICK_RANGE_SELECT::row_in_ranges()
{
8628
  QUICK_RANGE *res;
8629 8630 8631 8632 8633
  uint min= 0;
  uint max= ranges.elements - 1;
  uint mid= (max + min)/2;

  while (min != max)
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8634
  {
8635 8636 8637 8638 8639 8640 8641 8642 8643
    if (cmp_next(*(QUICK_RANGE**)dynamic_array_ptr(&ranges, mid)))
    {
      /* current row value > mid->max */
      min= mid + 1;
    }
    else
      max= mid;
    mid= (min + max) / 2;
  }
8644 8645
  res= *(QUICK_RANGE**)dynamic_array_ptr(&ranges, mid);
  return (!cmp_next(res) && !cmp_prev(res));
8646 8647
}

8648
/*
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  This is a hack: we inherit from QUICK_SELECT so that we can use the
  get_next() interface, but we have to hold a pointer to the original
  QUICK_SELECT because its data are used all over the place.  What
  should be done is to factor out the data that is needed into a base
  class (QUICK_SELECT), and then have two subclasses (_ASC and _DESC)
  which handle the ranges and implement the get_next() function.  But
  for now, this seems to work right at least.
8656
 */
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8657

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8658
QUICK_SELECT_DESC::QUICK_SELECT_DESC(QUICK_RANGE_SELECT *q,
8659
                                     uint used_key_parts_arg)
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8660
 :QUICK_RANGE_SELECT(*q), rev_it(rev_ranges),
8661
  used_key_parts (used_key_parts_arg)
8662
{
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  QUICK_RANGE *r;
8664 8665 8666 8667 8668 8669 8670
  /* 
    Use default MRR implementation for reverse scans. No table engine
    currently can do an MRR scan with output in reverse index order.
  */
  multi_range_length= 0;
  multi_range= NULL;
  multi_range_buff= NULL;
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8671

8672
  QUICK_RANGE **pr= (QUICK_RANGE**)ranges.buffer;
8673 8674
  QUICK_RANGE **end_range= pr + ranges.elements;
  for (; pr!=end_range; pr++)
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    rev_ranges.push_front(*pr);
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8676

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  /* Remove EQ_RANGE flag for keys that are not using the full key */
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  for (r = rev_it++; r; r = rev_it++)
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  {
    if ((r->flag & EQ_RANGE) &&
	head->key_info[index].key_length != r->max_length)
      r->flag&= ~EQ_RANGE;
  }
  rev_it.rewind();
  q->dont_free=1;				// Don't free shared mem
  delete q;
8687 8688
}

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8689

8690 8691 8692 8693 8694 8695
int QUICK_SELECT_DESC::get_next()
{
  DBUG_ENTER("QUICK_SELECT_DESC::get_next");

  /* The max key is handled as follows:
   *   - if there is NO_MAX_RANGE, start at the end and move backwards
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8696 8697
   *   - if it is an EQ_RANGE, which means that max key covers the entire
   *     key, go directly to the key and read through it (sorting backwards is
8698 8699 8700 8701 8702 8703 8704 8705 8706 8707
   *     same as sorting forwards)
   *   - if it is NEAR_MAX, go to the key or next, step back once, and
   *     move backwards
   *   - otherwise (not NEAR_MAX == include the key), go after the key,
   *     step back once, and move backwards
   */

  for (;;)
  {
    int result;
8708
    if (last_range)
8709
    {						// Already read through key
8710 8711
      result = ((last_range->flag & EQ_RANGE && 
                 used_key_parts <= head->key_info[index].key_parts) ? 
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8712
                file->index_next_same(record, last_range->min_key,
8713 8714
                                      last_range->min_length) :
                file->index_prev(record));
8715 8716 8717 8718 8719 8720 8721 8722 8723
      if (!result)
      {
	if (cmp_prev(*rev_it.ref()) == 0)
	  DBUG_RETURN(0);
      }
      else if (result != HA_ERR_END_OF_FILE)
	DBUG_RETURN(result);
    }

8724
    if (!(last_range= rev_it++))
8725 8726
      DBUG_RETURN(HA_ERR_END_OF_FILE);		// All ranges used

8727
    if (last_range->flag & NO_MAX_RANGE)        // Read last record
8728
    {
8729 8730 8731
      int local_error;
      if ((local_error=file->index_last(record)))
	DBUG_RETURN(local_error);		// Empty table
8732
      if (cmp_prev(last_range) == 0)
8733
	DBUG_RETURN(0);
8734
      last_range= 0;                            // No match; go to next range
8735 8736 8737
      continue;
    }

8738 8739 8740
    if (last_range->flag & EQ_RANGE &&
        used_key_parts <= head->key_info[index].key_parts)

8741
    {
8742 8743 8744
      result = file->index_read_map(record, last_range->max_key,
                                    last_range->max_keypart_map,
                                    HA_READ_KEY_EXACT);
8745 8746 8747
    }
    else
    {
8748
      DBUG_ASSERT(last_range->flag & NEAR_MAX ||
8749 8750
                  (last_range->flag & EQ_RANGE && 
                   used_key_parts > head->key_info[index].key_parts) ||
8751
                  range_reads_after_key(last_range));
8752 8753 8754 8755 8756
      result=file->index_read_map(record, last_range->max_key,
                                  last_range->max_keypart_map,
                                  ((last_range->flag & NEAR_MAX) ?
                                   HA_READ_BEFORE_KEY :
                                   HA_READ_PREFIX_LAST_OR_PREV));
8757 8758 8759
    }
    if (result)
    {
8760
      if (result != HA_ERR_KEY_NOT_FOUND && result != HA_ERR_END_OF_FILE)
8761
	DBUG_RETURN(result);
8762
      last_range= 0;                            // Not found, to next range
8763 8764
      continue;
    }
8765
    if (cmp_prev(last_range) == 0)
8766
    {
8767 8768
      if (last_range->flag == (UNIQUE_RANGE | EQ_RANGE))
	last_range= 0;				// Stop searching
8769 8770
      DBUG_RETURN(0);				// Found key is in range
    }
8771
    last_range= 0;                              // To next range
8772 8773 8774
  }
}

8775

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/*
  Compare if found key is over max-value
  Returns 0 if key <= range->max_key
*/

int QUICK_RANGE_SELECT::cmp_next(QUICK_RANGE *range_arg)
{
  if (range_arg->flag & NO_MAX_RANGE)
    return 0;                                   /* key can't be to large */

  KEY_PART *key_part=key_parts;
  uint store_length;

8789
  for (uchar *key=range_arg->max_key, *end=key+range_arg->max_length;
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       key < end;
       key+= store_length, key_part++)
  {
    int cmp;
    store_length= key_part->store_length;
    if (key_part->null_bit)
    {
      if (*key)
      {
        if (!key_part->field->is_null())
          return 1;
        continue;
      }
      else if (key_part->field->is_null())
        return 0;
      key++;					// Skip null byte
      store_length--;
    }
8808
    if ((cmp=key_part->field->key_cmp(key, key_part->length)) < 0)
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      return 0;
    if (cmp > 0)
      return 1;
  }
  return (range_arg->flag & NEAR_MAX) ? 1 : 0;          // Exact match
}


8817
/*
8818 8819 8820
  Returns 0 if found key is inside range (found key >= range->min_key).
*/

8821
int QUICK_RANGE_SELECT::cmp_prev(QUICK_RANGE *range_arg)
8822
{
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8823
  int cmp;
8824
  if (range_arg->flag & NO_MIN_RANGE)
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    return 0;					/* key can't be to small */
8826

8827
  cmp= key_cmp(key_part_info, range_arg->min_key,
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8828
               range_arg->min_length);
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  if (cmp > 0 || cmp == 0 && !(range_arg->flag & NEAR_MIN))
    return 0;
  return 1;                                     // outside of range
8832 8833
}

8834

8835
/*
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 * TRUE if this range will require using HA_READ_AFTER_KEY
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   See comment in get_next() about this
8838
 */
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8839

8840
bool QUICK_SELECT_DESC::range_reads_after_key(QUICK_RANGE *range_arg)
8841
{
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8842
  return ((range_arg->flag & (NO_MAX_RANGE | NEAR_MAX)) ||
8843
	  !(range_arg->flag & EQ_RANGE) ||
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	  head->key_info[index].key_length != range_arg->max_length) ? 1 : 0;
8845 8846
}

8847

8848 8849 8850 8851 8852 8853 8854 8855 8856
void QUICK_RANGE_SELECT::add_info_string(String *str)
{
  KEY *key_info= head->key_info + index;
  str->append(key_info->name);
}

void QUICK_INDEX_MERGE_SELECT::add_info_string(String *str)
{
  QUICK_RANGE_SELECT *quick;
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  bool first= TRUE;
8858
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
8859
  str->append(STRING_WITH_LEN("sort_union("));
8860 8861 8862 8863 8864
  while ((quick= it++))
  {
    if (!first)
      str->append(',');
    else
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      first= FALSE;
8866 8867 8868 8869 8870 8871 8872 8873 8874 8875 8876 8877
    quick->add_info_string(str);
  }
  if (pk_quick_select)
  {
    str->append(',');
    pk_quick_select->add_info_string(str);
  }
  str->append(')');
}

void QUICK_ROR_INTERSECT_SELECT::add_info_string(String *str)
{
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  bool first= TRUE;
8879 8880
  QUICK_RANGE_SELECT *quick;
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
8881
  str->append(STRING_WITH_LEN("intersect("));
8882 8883 8884 8885 8886
  while ((quick= it++))
  {
    KEY *key_info= head->key_info + quick->index;
    if (!first)
      str->append(',');
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    else
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      first= FALSE;
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    str->append(key_info->name);
  }
  if (cpk_quick)
  {
    KEY *key_info= head->key_info + cpk_quick->index;
    str->append(',');
    str->append(key_info->name);
  }
  str->append(')');
}

void QUICK_ROR_UNION_SELECT::add_info_string(String *str)
{
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8902
  bool first= TRUE;
8903 8904
  QUICK_SELECT_I *quick;
  List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
8905
  str->append(STRING_WITH_LEN("union("));
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  while ((quick= it++))
  {
    if (!first)
      str->append(',');
    else
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      first= FALSE;
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    quick->add_info_string(str);
  }
  str->append(')');
}


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void QUICK_RANGE_SELECT::add_keys_and_lengths(String *key_names,
8919
                                              String *used_lengths)
8920 8921 8922 8923 8924 8925 8926 8927 8928
{
  char buf[64];
  uint length;
  KEY *key_info= head->key_info + index;
  key_names->append(key_info->name);
  length= longlong2str(max_used_key_length, buf, 10) - buf;
  used_lengths->append(buf, length);
}

8929 8930
void QUICK_INDEX_MERGE_SELECT::add_keys_and_lengths(String *key_names,
                                                    String *used_lengths)
8931 8932 8933
{
  char buf[64];
  uint length;
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8934
  bool first= TRUE;
8935
  QUICK_RANGE_SELECT *quick;
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8937 8938 8939
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  while ((quick= it++))
  {
8940
    if (first)
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8941
      first= FALSE;
8942 8943
    else
    {
8944 8945
      key_names->append(',');
      used_lengths->append(',');
8946
    }
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8948 8949
    KEY *key_info= head->key_info + quick->index;
    key_names->append(key_info->name);
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    length= longlong2str(quick->max_used_key_length, buf, 10) - buf;
    used_lengths->append(buf, length);
  }
  if (pk_quick_select)
  {
    KEY *key_info= head->key_info + pk_quick_select->index;
    key_names->append(',');
    key_names->append(key_info->name);
    length= longlong2str(pk_quick_select->max_used_key_length, buf, 10) - buf;
    used_lengths->append(',');
    used_lengths->append(buf, length);
  }
}

8964 8965
void QUICK_ROR_INTERSECT_SELECT::add_keys_and_lengths(String *key_names,
                                                      String *used_lengths)
8966 8967 8968
{
  char buf[64];
  uint length;
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  bool first= TRUE;
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  QUICK_RANGE_SELECT *quick;
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  while ((quick= it++))
  {
    KEY *key_info= head->key_info + quick->index;
    if (first)
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      first= FALSE;
8977
    else
8978 8979
    {
      key_names->append(',');
8980
      used_lengths->append(',');
8981 8982
    }
    key_names->append(key_info->name);
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    length= longlong2str(quick->max_used_key_length, buf, 10) - buf;
    used_lengths->append(buf, length);
  }
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  if (cpk_quick)
  {
    KEY *key_info= head->key_info + cpk_quick->index;
    key_names->append(',');
    key_names->append(key_info->name);
    length= longlong2str(cpk_quick->max_used_key_length, buf, 10) - buf;
    used_lengths->append(',');
    used_lengths->append(buf, length);
  }
}

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void QUICK_ROR_UNION_SELECT::add_keys_and_lengths(String *key_names,
                                                  String *used_lengths)
9000
{
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  bool first= TRUE;
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  QUICK_SELECT_I *quick;
  List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
  while ((quick= it++))
  {
    if (first)
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      first= FALSE;
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    else
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    {
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      used_lengths->append(',');
      key_names->append(',');
    }
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    quick->add_keys_and_lengths(key_names, used_lengths);
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  }
}

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/*******************************************************************************
* Implementation of QUICK_GROUP_MIN_MAX_SELECT
*******************************************************************************/

static inline uint get_field_keypart(KEY *index, Field *field);
static inline SEL_ARG * get_index_range_tree(uint index, SEL_TREE* range_tree,
                                             PARAM *param, uint *param_idx);
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static bool get_constant_key_infix(KEY *index_info, SEL_ARG *index_range_tree,
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                       KEY_PART_INFO *first_non_group_part,
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                       KEY_PART_INFO *min_max_arg_part,
                       KEY_PART_INFO *last_part, THD *thd,
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                       uchar *key_infix, uint *key_infix_len,
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                       KEY_PART_INFO **first_non_infix_part);
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static bool
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check_group_min_max_predicates(COND *cond, Item_field *min_max_arg_item,
                               Field::imagetype image_type);
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static void
cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts,
                   uint group_key_parts, SEL_TREE *range_tree,
                   SEL_ARG *index_tree, ha_rows quick_prefix_records,
                   bool have_min, bool have_max,
                   double *read_cost, ha_rows *records);
9041

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/*
  Test if this access method is applicable to a GROUP query with MIN/MAX
  functions, and if so, construct a new TRP object.

  SYNOPSIS
    get_best_group_min_max()
    param    Parameter from test_quick_select
    sel_tree Range tree generated by get_mm_tree

  DESCRIPTION
    Test whether a query can be computed via a QUICK_GROUP_MIN_MAX_SELECT.
    Queries computable via a QUICK_GROUP_MIN_MAX_SELECT must satisfy the
    following conditions:
    A) Table T has at least one compound index I of the form:
       I = <A_1, ...,A_k, [B_1,..., B_m], C, [D_1,...,D_n]>
    B) Query conditions:
    B0. Q is over a single table T.
    B1. The attributes referenced by Q are a subset of the attributes of I.
    B2. All attributes QA in Q can be divided into 3 overlapping groups:
        - SA = {S_1, ..., S_l, [C]} - from the SELECT clause, where C is
          referenced by any number of MIN and/or MAX functions if present.
        - WA = {W_1, ..., W_p} - from the WHERE clause
        - GA = <G_1, ..., G_k> - from the GROUP BY clause (if any)
             = SA              - if Q is a DISTINCT query (based on the
                                 equivalence of DISTINCT and GROUP queries.
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        - NGA = QA - (GA union C) = {NG_1, ..., NG_m} - the ones not in
          GROUP BY and not referenced by MIN/MAX functions.
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        with the following properties specified below.
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    B3. If Q has a GROUP BY WITH ROLLUP clause the access method is not 
        applicable.
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    SA1. There is at most one attribute in SA referenced by any number of
         MIN and/or MAX functions which, which if present, is denoted as C.
    SA2. The position of the C attribute in the index is after the last A_k.
    SA3. The attribute C can be referenced in the WHERE clause only in
         predicates of the forms:
         - (C {< | <= | > | >= | =} const)
         - (const {< | <= | > | >= | =} C)
         - (C between const_i and const_j)
         - C IS NULL
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         - C IS NOT NULL
         - C != const
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    SA4. If Q has a GROUP BY clause, there are no other aggregate functions
         except MIN and MAX. For queries with DISTINCT, aggregate functions
         are allowed.
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    SA5. The select list in DISTINCT queries should not contain expressions.
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    GA1. If Q has a GROUP BY clause, then GA is a prefix of I. That is, if
         G_i = A_j => i = j.
    GA2. If Q has a DISTINCT clause, then there is a permutation of SA that
         forms a prefix of I. This permutation is used as the GROUP clause
         when the DISTINCT query is converted to a GROUP query.
    GA3. The attributes in GA may participate in arbitrary predicates, divided
         into two groups:
         - RNG(G_1,...,G_q ; where q <= k) is a range condition over the
           attributes of a prefix of GA
         - PA(G_i1,...G_iq) is an arbitrary predicate over an arbitrary subset
           of GA. Since P is applied to only GROUP attributes it filters some
           groups, and thus can be applied after the grouping.
    GA4. There are no expressions among G_i, just direct column references.
    NGA1.If in the index I there is a gap between the last GROUP attribute G_k,
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         and the MIN/MAX attribute C, then NGA must consist of exactly the
         index attributes that constitute the gap. As a result there is a
         permutation of NGA that coincides with the gap in the index
         <B_1, ..., B_m>.
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    NGA2.If BA <> {}, then the WHERE clause must contain a conjunction EQ of
         equality conditions for all NG_i of the form (NG_i = const) or
         (const = NG_i), such that each NG_i is referenced in exactly one
         conjunct. Informally, the predicates provide constants to fill the
         gap in the index.
    WA1. There are no other attributes in the WHERE clause except the ones
         referenced in predicates RNG, PA, PC, EQ defined above. Therefore
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         WA is subset of (GA union NGA union C) for GA,NGA,C that pass the
         above tests. By transitivity then it also follows that each WA_i
         participates in the index I (if this was already tested for GA, NGA
         and C).
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    C) Overall query form:
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       SELECT EXPR([A_1,...,A_k], [B_1,...,B_m], [MIN(C)], [MAX(C)])
         FROM T
        WHERE [RNG(A_1,...,A_p ; where p <= k)]
         [AND EQ(B_1,...,B_m)]
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         [AND PC(C)]
         [AND PA(A_i1,...,A_iq)]
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       GROUP BY A_1,...,A_k
       [HAVING PH(A_1, ..., B_1,..., C)]
    where EXPR(...) is an arbitrary expression over some or all SELECT fields,
    or:
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       SELECT DISTINCT A_i1,...,A_ik
         FROM T
        WHERE [RNG(A_1,...,A_p ; where p <= k)]
         [AND PA(A_i1,...,A_iq)];

  NOTES
    If the current query satisfies the conditions above, and if
    (mem_root! = NULL), then the function constructs and returns a new TRP
    object, that is later used to construct a new QUICK_GROUP_MIN_MAX_SELECT.
    If (mem_root == NULL), then the function only tests whether the current
    query satisfies the conditions above, and, if so, sets
    is_applicable = TRUE.

    Queries with DISTINCT for which index access can be used are transformed
    into equivalent group-by queries of the form:

    SELECT A_1,...,A_k FROM T
     WHERE [RNG(A_1,...,A_p ; where p <= k)]
      [AND PA(A_i1,...,A_iq)]
    GROUP BY A_1,...,A_k;

    The group-by list is a permutation of the select attributes, according
    to their order in the index.

  TODO
  - What happens if the query groups by the MIN/MAX field, and there is no
    other field as in: "select min(a) from t1 group by a" ?
  - We assume that the general correctness of the GROUP-BY query was checked
    before this point. Is this correct, or do we have to check it completely?
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  - Lift the limitation in condition (B3), that is, make this access method 
    applicable to ROLLUP queries.
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  RETURN
    If mem_root != NULL
    - valid TRP_GROUP_MIN_MAX object if this QUICK class can be used for
      the query
    -  NULL o/w.
    If mem_root == NULL
    - NULL
*/

static TRP_GROUP_MIN_MAX *
get_best_group_min_max(PARAM *param, SEL_TREE *tree)
{
  THD *thd= param->thd;
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  JOIN *join= thd->lex->current_select->join;
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  TABLE *table= param->table;
  bool have_min= FALSE;              /* TRUE if there is a MIN function. */
  bool have_max= FALSE;              /* TRUE if there is a MAX function. */
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  Item_field *min_max_arg_item= NULL; // The argument of all MIN/MAX functions
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  KEY_PART_INFO *min_max_arg_part= NULL; /* The corresponding keypart. */
  uint group_prefix_len= 0; /* Length (in bytes) of the key prefix. */
  KEY *index_info= NULL;    /* The index chosen for data access. */
  uint index= 0;            /* The id of the chosen index. */
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  uint group_key_parts= 0;  // Number of index key parts in the group prefix.
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  uint used_key_parts= 0;   /* Number of index key parts used for access. */
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  uchar key_infix[MAX_KEY_LENGTH]; /* Constants from equality predicates.*/
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  uint key_infix_len= 0;          /* Length of key_infix. */
  TRP_GROUP_MIN_MAX *read_plan= NULL; /* The eventually constructed TRP. */
  uint key_part_nr;
  ORDER *tmp_group;
  Item *item;
  Item_field *item_field;
  DBUG_ENTER("get_best_group_min_max");

  /* Perform few 'cheap' tests whether this access method is applicable. */
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  if (!join)
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    DBUG_RETURN(NULL);        /* This is not a select statement. */
  if ((join->tables != 1) ||  /* The query must reference one table. */
      ((!join->group_list) && /* Neither GROUP BY nor a DISTINCT query. */
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       (!join->select_distinct)) ||
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      (join->select_lex->olap == ROLLUP_TYPE)) /* Check (B3) for ROLLUP */
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    DBUG_RETURN(NULL);
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  if (table->s->keys == 0)        /* There are no indexes to use. */
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    DBUG_RETURN(NULL);

  /* Analyze the query in more detail. */
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  List_iterator<Item> select_items_it(join->fields_list);
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9209
  /* Check (SA1,SA4) and store the only MIN/MAX argument - the C attribute.*/
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  if (join->make_sum_func_list(join->all_fields, join->fields_list, 1))
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    DBUG_RETURN(NULL);
  if (join->sum_funcs[0])
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  {
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    Item_sum *min_max_item;
    Item_sum **func_ptr= join->sum_funcs;
    while ((min_max_item= *(func_ptr++)))
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    {
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      if (min_max_item->sum_func() == Item_sum::MIN_FUNC)
        have_min= TRUE;
      else if (min_max_item->sum_func() == Item_sum::MAX_FUNC)
        have_max= TRUE;
      else
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        DBUG_RETURN(NULL);

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      /* The argument of MIN/MAX. */
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      Item *expr= min_max_item->get_arg(0)->real_item();
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      if (expr->type() == Item::FIELD_ITEM) /* Is it an attribute? */
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      {
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        if (! min_max_arg_item)
          min_max_arg_item= (Item_field*) expr;
        else if (! min_max_arg_item->eq(expr, 1))
          DBUG_RETURN(NULL);
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      }
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      else
        DBUG_RETURN(NULL);
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    }
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  }
9238

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  /* Check (SA5). */
  if (join->select_distinct)
  {
    while ((item= select_items_it++))
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    {
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      if (item->type() != Item::FIELD_ITEM)
        DBUG_RETURN(NULL);
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    }
  }

  /* Check (GA4) - that there are no expressions among the group attributes. */
  for (tmp_group= join->group_list; tmp_group; tmp_group= tmp_group->next)
  {
    if ((*tmp_group->item)->type() != Item::FIELD_ITEM)
      DBUG_RETURN(NULL);
  }

  /*
    Check that table has at least one compound index such that the conditions
    (GA1,GA2) are all TRUE. If there is more than one such index, select the
    first one. Here we set the variables: group_prefix_len and index_info.
  */
  KEY *cur_index_info= table->key_info;
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  KEY *cur_index_info_end= cur_index_info + table->s->keys;
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  /* Cost-related variables for the best index so far. */
  double best_read_cost= DBL_MAX;
  ha_rows best_records= 0;
  SEL_ARG *best_index_tree= NULL;
  ha_rows best_quick_prefix_records= 0;
  uint best_param_idx= 0;
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  const uint pk= param->table->s->primary_key;
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  SEL_ARG *cur_index_tree= NULL;
  ha_rows cur_quick_prefix_records= 0;
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  uint cur_param_idx=MAX_KEY;
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  for (uint cur_index= 0 ; cur_index_info != cur_index_info_end ;
       cur_index_info++, cur_index++)
  {
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    KEY_PART_INFO *cur_part;
    KEY_PART_INFO *end_part; /* Last part for loops. */
    /* Last index part. */
    KEY_PART_INFO *last_part;
    KEY_PART_INFO *first_non_group_part;
    KEY_PART_INFO *first_non_infix_part;
    uint key_infix_parts;
    uint cur_group_key_parts= 0;
    uint cur_group_prefix_len= 0;
    double cur_read_cost;
    ha_rows cur_records;
    key_map used_key_parts_map;
    uint cur_key_infix_len= 0;
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    uchar cur_key_infix[MAX_KEY_LENGTH];
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    uint cur_used_key_parts;
    
9294
    /* Check (B1) - if current index is covering. */
9295
    if (!table->covering_keys.is_set(cur_index))
9296
      goto next_index;
9297

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    /*
      If the current storage manager is such that it appends the primary key to
      each index, then the above condition is insufficient to check if the
      index is covering. In such cases it may happen that some fields are
      covered by the PK index, but not by the current index. Since we can't
      use the concatenation of both indexes for index lookup, such an index
      does not qualify as covering in our case. If this is the case, below
      we check that all query fields are indeed covered by 'cur_index'.
    */
    if (pk < MAX_KEY && cur_index != pk &&
9308
        (table->file->ha_table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX))
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    {
      /* For each table field */
      for (uint i= 0; i < table->s->fields; i++)
      {
        Field *cur_field= table->field[i];
        /*
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          If the field is used in the current query ensure that it's
          part of 'cur_index'
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9317
        */
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        if (bitmap_is_set(table->read_set, cur_field->field_index) &&
            !cur_field->part_of_key_not_clustered.is_set(cur_index))
          goto next_index;                  // Field was not part of key
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      }
    }

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    /*
      Check (GA1) for GROUP BY queries.
    */
    if (join->group_list)
    {
      cur_part= cur_index_info->key_part;
      end_part= cur_part + cur_index_info->key_parts;
      /* Iterate in parallel over the GROUP list and the index parts. */
      for (tmp_group= join->group_list; tmp_group && (cur_part != end_part);
           tmp_group= tmp_group->next, cur_part++)
      {
        /*
          TODO:
          tmp_group::item is an array of Item, is it OK to consider only the
          first Item? If so, then why? What is the array for?
        */
        /* Above we already checked that all group items are fields. */
        DBUG_ASSERT((*tmp_group->item)->type() == Item::FIELD_ITEM);
        Item_field *group_field= (Item_field *) (*tmp_group->item);
        if (group_field->field->eq(cur_part->field))
        {
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          cur_group_prefix_len+= cur_part->store_length;
          ++cur_group_key_parts;
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        }
        else
          goto next_index;
      }
    }
    /*
      Check (GA2) if this is a DISTINCT query.
      If GA2, then Store a new ORDER object in group_fields_array at the
      position of the key part of item_field->field. Thus we get the ORDER
      objects for each field ordered as the corresponding key parts.
      Later group_fields_array of ORDER objects is used to convert the query
      to a GROUP query.
    */
    else if (join->select_distinct)
    {
9362
      select_items_it.rewind();
9363
      used_key_parts_map.clear_all();
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      uint max_key_part= 0;
9365
      while ((item= select_items_it++))
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      {
9367
        item_field= (Item_field*) item; /* (SA5) already checked above. */
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        /* Find the order of the key part in the index. */
        key_part_nr= get_field_keypart(cur_index_info, item_field->field);
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        /*
          Check if this attribute was already present in the select list.
          If it was present, then its corresponding key part was alredy used.
        */
9374
        if (used_key_parts_map.is_set(key_part_nr))
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9375
          continue;
9376
        if (key_part_nr < 1 || key_part_nr > join->fields_list.elements)
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          goto next_index;
        cur_part= cur_index_info->key_part + key_part_nr - 1;
9379
        cur_group_prefix_len+= cur_part->store_length;
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        used_key_parts_map.set_bit(key_part_nr);
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        ++cur_group_key_parts;
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        max_key_part= max(max_key_part,key_part_nr);
9383
      }
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      /*
        Check that used key parts forms a prefix of the index.
        To check this we compare bits in all_parts and cur_parts.
        all_parts have all bits set from 0 to (max_key_part-1).
        cur_parts have bits set for only used keyparts.
      */
      ulonglong all_parts, cur_parts;
      all_parts= (1<<max_key_part) - 1;
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      cur_parts= used_key_parts_map.to_ulonglong() >> 1;
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      if (all_parts != cur_parts)
        goto next_index;
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    }
    else
      DBUG_ASSERT(FALSE);

    /* Check (SA2). */
    if (min_max_arg_item)
    {
      key_part_nr= get_field_keypart(cur_index_info, min_max_arg_item->field);
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      if (key_part_nr <= cur_group_key_parts)
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        goto next_index;
      min_max_arg_part= cur_index_info->key_part + key_part_nr - 1;
    }

    /*
      Check (NGA1, NGA2) and extract a sequence of constants to be used as part
      of all search keys.
    */
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    /*
      If there is MIN/MAX, each keypart between the last group part and the
      MIN/MAX part must participate in one equality with constants, and all
      keyparts after the MIN/MAX part must not be referenced in the query.

      If there is no MIN/MAX, the keyparts after the last group part can be
      referenced only in equalities with constants, and the referenced keyparts
      must form a sequence without any gaps that starts immediately after the
      last group keypart.
    */
    last_part= cur_index_info->key_part + cur_index_info->key_parts;
    first_non_group_part= (cur_group_key_parts < cur_index_info->key_parts) ?
                          cur_index_info->key_part + cur_group_key_parts :
                          NULL;
    first_non_infix_part= min_max_arg_part ?
                          (min_max_arg_part < last_part) ?
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                             min_max_arg_part :
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                             NULL :
                           NULL;
    if (first_non_group_part &&
        (!min_max_arg_part || (min_max_arg_part - first_non_group_part > 0)))
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    {
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      if (tree)
      {
        uint dummy;
        SEL_ARG *index_range_tree= get_index_range_tree(cur_index, tree, param,
                                                        &dummy);
        if (!get_constant_key_infix(cur_index_info, index_range_tree,
                                    first_non_group_part, min_max_arg_part,
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                                    last_part, thd, cur_key_infix, 
                                    &cur_key_infix_len,
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                                    &first_non_infix_part))
          goto next_index;
      }
      else if (min_max_arg_part &&
               (min_max_arg_part - first_non_group_part > 0))
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      {
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        /*
          There is a gap but no range tree, thus no predicates at all for the
          non-group keyparts.
        */
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        goto next_index;
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      }
      else if (first_non_group_part && join->conds)
      {
        /*
          If there is no MIN/MAX function in the query, but some index
          key part is referenced in the WHERE clause, then this index
          cannot be used because the WHERE condition over the keypart's
          field cannot be 'pushed' to the index (because there is no
          range 'tree'), and the WHERE clause must be evaluated before
          GROUP BY/DISTINCT.
        */
        /*
          Store the first and last keyparts that need to be analyzed
          into one array that can be passed as parameter.
        */
        KEY_PART_INFO *key_part_range[2];
        key_part_range[0]= first_non_group_part;
        key_part_range[1]= last_part;

        /* Check if cur_part is referenced in the WHERE clause. */
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        if (join->conds->walk(&Item::find_item_in_field_list_processor, 0,
9476
                              (uchar*) key_part_range))
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          goto next_index;
      }
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    }

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    /*
      Test (WA1) partially - that no other keypart after the last infix part is
      referenced in the query.
    */
    if (first_non_infix_part)
    {
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      cur_part= first_non_infix_part +
                (min_max_arg_part && (min_max_arg_part < last_part));
      for (; cur_part != last_part; cur_part++)
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      {
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        if (bitmap_is_set(table->read_set, cur_part->field->field_index))
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          goto next_index;
      }
    }

9496
    /* If we got to this point, cur_index_info passes the test. */
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9497
    key_infix_parts= cur_key_infix_len ? (uint) 
9498
                     (first_non_infix_part - first_non_group_part) : 0;
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    cur_used_key_parts= cur_group_key_parts + key_infix_parts;
9500

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    /* Compute the cost of using this index. */
    if (tree)
    {
      /* Find the SEL_ARG sub-tree that corresponds to the chosen index. */
      cur_index_tree= get_index_range_tree(cur_index, tree, param,
                                           &cur_param_idx);
      /* Check if this range tree can be used for prefix retrieval. */
      cur_quick_prefix_records= check_quick_select(param, cur_param_idx,
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                                                    cur_index_tree, TRUE);
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    }
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    cost_group_min_max(table, cur_index_info, cur_used_key_parts,
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                       cur_group_key_parts, tree, cur_index_tree,
                       cur_quick_prefix_records, have_min, have_max,
                       &cur_read_cost, &cur_records);
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    /*
      If cur_read_cost is lower than best_read_cost use cur_index.
      Do not compare doubles directly because they may have different
      representations (64 vs. 80 bits).
    */
    if (cur_read_cost < best_read_cost - (DBL_EPSILON * cur_read_cost))
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    {
      index_info= cur_index_info;
      index= cur_index;
      best_read_cost= cur_read_cost;
      best_records= cur_records;
      best_index_tree= cur_index_tree;
      best_quick_prefix_records= cur_quick_prefix_records;
      best_param_idx= cur_param_idx;
      group_key_parts= cur_group_key_parts;
      group_prefix_len= cur_group_prefix_len;
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      key_infix_len= cur_key_infix_len;
      if (key_infix_len)
        memcpy (key_infix, cur_key_infix, sizeof (key_infix));
      used_key_parts= cur_used_key_parts;
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    }
9536

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  next_index:;
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  }
  if (!index_info) /* No usable index found. */
    DBUG_RETURN(NULL);

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  /* Check (SA3) for the where clause. */
  if (join->conds && min_max_arg_item &&
      !check_group_min_max_predicates(join->conds, min_max_arg_item,
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                                      (index_info->flags & HA_SPATIAL) ?
                                      Field::itMBR : Field::itRAW))
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    DBUG_RETURN(NULL);

  /* The query passes all tests, so construct a new TRP object. */
  read_plan= new (param->mem_root)
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                 TRP_GROUP_MIN_MAX(have_min, have_max, min_max_arg_part,
                                   group_prefix_len, used_key_parts,
                                   group_key_parts, index_info, index,
                                   key_infix_len,
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                                   (key_infix_len > 0) ? key_infix : NULL,
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                                   tree, best_index_tree, best_param_idx,
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                                   best_quick_prefix_records);
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  if (read_plan)
  {
    if (tree && read_plan->quick_prefix_records == 0)
      DBUG_RETURN(NULL);

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    read_plan->read_cost= best_read_cost;
    read_plan->records=   best_records;

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    DBUG_PRINT("info",
               ("Returning group min/max plan: cost: %g, records: %lu",
                read_plan->read_cost, (ulong) read_plan->records));
  }

  DBUG_RETURN(read_plan);
}


/*
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  Check that the MIN/MAX attribute participates only in range predicates
  with constants.
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  SYNOPSIS
    check_group_min_max_predicates()
    cond              tree (or subtree) describing all or part of the WHERE
                      clause being analyzed
    min_max_arg_item  the field referenced by the MIN/MAX function(s)
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    min_max_arg_part  the keypart of the MIN/MAX argument if any
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  DESCRIPTION
    The function walks recursively over the cond tree representing a WHERE
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    clause, and checks condition (SA3) - if a field is referenced by a MIN/MAX
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    aggregate function, it is referenced only by one of the following
    predicates: {=, !=, <, <=, >, >=, between, is null, is not null}.
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  RETURN
    TRUE  if cond passes the test
    FALSE o/w
*/

static bool
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check_group_min_max_predicates(COND *cond, Item_field *min_max_arg_item,
                               Field::imagetype image_type)
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{
  DBUG_ENTER("check_group_min_max_predicates");
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  DBUG_ASSERT(cond && min_max_arg_item);
9603

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  cond= cond->real_item();
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  Item::Type cond_type= cond->type();
  if (cond_type == Item::COND_ITEM) /* 'AND' or 'OR' */
  {
    DBUG_PRINT("info", ("Analyzing: %s", ((Item_func*) cond)->func_name()));
    List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list());
    Item *and_or_arg;
    while ((and_or_arg= li++))
    {
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      if (!check_group_min_max_predicates(and_or_arg, min_max_arg_item,
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                                         image_type))
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        DBUG_RETURN(FALSE);
    }
    DBUG_RETURN(TRUE);
  }

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  /*
    TODO:
    This is a very crude fix to handle sub-selects in the WHERE clause
    (Item_subselect objects). With the test below we rule out from the
    optimization all queries with subselects in the WHERE clause. What has to
    be done, is that here we should analyze whether the subselect references
    the MIN/MAX argument field, and disallow the optimization only if this is
    so.
  */
  if (cond_type == Item::SUBSELECT_ITEM)
    DBUG_RETURN(FALSE);
  
  /* We presume that at this point there are no other Items than functions. */
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  DBUG_ASSERT(cond_type == Item::FUNC_ITEM);

  /* Test if cond references only group-by or non-group fields. */
  Item_func *pred= (Item_func*) cond;
  Item **arguments= pred->arguments();
  Item *cur_arg;
  DBUG_PRINT("info", ("Analyzing: %s", pred->func_name()));
  for (uint arg_idx= 0; arg_idx < pred->argument_count (); arg_idx++)
  {
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    cur_arg= arguments[arg_idx]->real_item();
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    DBUG_PRINT("info", ("cur_arg: %s", cur_arg->full_name()));
    if (cur_arg->type() == Item::FIELD_ITEM)
    {
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      if (min_max_arg_item->eq(cur_arg, 1)) 
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      {
       /*
         If pred references the MIN/MAX argument, check whether pred is a range
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         condition that compares the MIN/MAX argument with a constant.
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       */
        Item_func::Functype pred_type= pred->functype();
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        if (pred_type != Item_func::EQUAL_FUNC     &&
            pred_type != Item_func::LT_FUNC        &&
            pred_type != Item_func::LE_FUNC        &&
            pred_type != Item_func::GT_FUNC        &&
            pred_type != Item_func::GE_FUNC        &&
            pred_type != Item_func::BETWEEN        &&
            pred_type != Item_func::ISNULL_FUNC    &&
            pred_type != Item_func::ISNOTNULL_FUNC &&
            pred_type != Item_func::EQ_FUNC        &&
            pred_type != Item_func::NE_FUNC)
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          DBUG_RETURN(FALSE);

        /* Check that pred compares min_max_arg_item with a constant. */
        Item *args[3];
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        bzero(args, 3 * sizeof(Item*));
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        bool inv;
        /* Test if this is a comparison of a field and a constant. */
        if (!simple_pred(pred, args, &inv))
          DBUG_RETURN(FALSE);
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        /* Check for compatible string comparisons - similar to get_mm_leaf. */
        if (args[0] && args[1] && !args[2] && // this is a binary function
            min_max_arg_item->result_type() == STRING_RESULT &&
            /*
              Don't use an index when comparing strings of different collations.
            */
            ((args[1]->result_type() == STRING_RESULT &&
              image_type == Field::itRAW &&
              ((Field_str*) min_max_arg_item->field)->charset() !=
              pred->compare_collation())
             ||
             /*
               We can't always use indexes when comparing a string index to a
               number.
             */
             (args[1]->result_type() != STRING_RESULT &&
              min_max_arg_item->field->cmp_type() != args[1]->result_type())))
          DBUG_RETURN(FALSE);
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      }
    }
    else if (cur_arg->type() == Item::FUNC_ITEM)
    {
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      if (!check_group_min_max_predicates(cur_arg, min_max_arg_item,
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                                         image_type))
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        DBUG_RETURN(FALSE);
    }
    else if (cur_arg->const_item())
    {
      DBUG_RETURN(TRUE);
    }
    else
      DBUG_RETURN(FALSE);
  }

  DBUG_RETURN(TRUE);
}


/*
  Extract a sequence of constants from a conjunction of equality predicates.

  SYNOPSIS
    get_constant_key_infix()
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    index_info             [in]  Descriptor of the chosen index.
    index_range_tree       [in]  Range tree for the chosen index
    first_non_group_part   [in]  First index part after group attribute parts
    min_max_arg_part       [in]  The keypart of the MIN/MAX argument if any
    last_part              [in]  Last keypart of the index
    thd                    [in]  Current thread
    key_infix              [out] Infix of constants to be used for index lookup
    key_infix_len          [out] Lenghth of the infix
    first_non_infix_part   [out] The first keypart after the infix (if any)
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  DESCRIPTION
    Test conditions (NGA1, NGA2) from get_best_group_min_max(). Namely,
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    for each keypart field NGF_i not in GROUP-BY, check that there is a
    constant equality predicate among conds with the form (NGF_i = const_ci) or
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    (const_ci = NGF_i).
    Thus all the NGF_i attributes must fill the 'gap' between the last group-by
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    attribute and the MIN/MAX attribute in the index (if present). If these
    conditions hold, copy each constant from its corresponding predicate into
    key_infix, in the order its NG_i attribute appears in the index, and update
    key_infix_len with the total length of the key parts in key_infix.

  RETURN
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    TRUE  if the index passes the test
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    FALSE o/w
*/

static bool
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get_constant_key_infix(KEY *index_info, SEL_ARG *index_range_tree,
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                       KEY_PART_INFO *first_non_group_part,
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                       KEY_PART_INFO *min_max_arg_part,
                       KEY_PART_INFO *last_part, THD *thd,
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                       uchar *key_infix, uint *key_infix_len,
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                       KEY_PART_INFO **first_non_infix_part)
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{
  SEL_ARG       *cur_range;
  KEY_PART_INFO *cur_part;
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  /* End part for the first loop below. */
  KEY_PART_INFO *end_part= min_max_arg_part ? min_max_arg_part : last_part;
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  *key_infix_len= 0;
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  uchar *key_ptr= key_infix;
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  for (cur_part= first_non_group_part; cur_part != end_part; cur_part++)
  {
    /*
      Find the range tree for the current keypart. We assume that
      index_range_tree points to the leftmost keypart in the index.
    */
    for (cur_range= index_range_tree; cur_range;
         cur_range= cur_range->next_key_part)
    {
      if (cur_range->field->eq(cur_part->field))
        break;
    }
    if (!cur_range)
    {
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      if (min_max_arg_part)
        return FALSE; /* The current keypart has no range predicates at all. */
      else
      {
        *first_non_infix_part= cur_part;
        return TRUE;
      }
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    }

    /* Check that the current range tree is a single point interval. */
    if (cur_range->prev || cur_range->next)
      return FALSE; /* This is not the only range predicate for the field. */
    if ((cur_range->min_flag & NO_MIN_RANGE) ||
        (cur_range->max_flag & NO_MAX_RANGE) ||
        (cur_range->min_flag & NEAR_MIN) || (cur_range->max_flag & NEAR_MAX))
      return FALSE;

    uint field_length= cur_part->store_length;
    if ((cur_range->maybe_null &&
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         cur_range->min_value[0] && cur_range->max_value[0]) ||
        !memcmp(cur_range->min_value, cur_range->max_value, field_length))
    {
      /* cur_range specifies 'IS NULL' or an equality condition. */
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      memcpy(key_ptr, cur_range->min_value, field_length);
      key_ptr+= field_length;
      *key_infix_len+= field_length;
    }
    else
      return FALSE;
  }

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  if (!min_max_arg_part && (cur_part == last_part))
    *first_non_infix_part= last_part;

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  return TRUE;
}


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/*
  Find the key part referenced by a field.

  SYNOPSIS
    get_field_keypart()
    index  descriptor of an index
    field  field that possibly references some key part in index

  NOTES
    The return value can be used to get a KEY_PART_INFO pointer by
    part= index->key_part + get_field_keypart(...) - 1;

  RETURN
    Positive number which is the consecutive number of the key part, or
    0 if field does not reference any index field.
*/

static inline uint
get_field_keypart(KEY *index, Field *field)
{
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  KEY_PART_INFO *part, *end;
9830

9831
  for (part= index->key_part, end= part + index->key_parts; part < end; part++)
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  {
    if (field->eq(part->field))
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      return part - index->key_part + 1;
9835
  }
9836
  return 0;
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}


/*
  Find the SEL_ARG sub-tree that corresponds to the chosen index.

  SYNOPSIS
    get_index_range_tree()
    index     [in]  The ID of the index being looked for
    range_tree[in]  Tree of ranges being searched
    param     [in]  PARAM from SQL_SELECT::test_quick_select
    param_idx [out] Index in the array PARAM::key that corresponds to 'index'

  DESCRIPTION

    A SEL_TREE contains range trees for all usable indexes. This procedure
    finds the SEL_ARG sub-tree for 'index'. The members of a SEL_TREE are
    ordered in the same way as the members of PARAM::key, thus we first find
    the corresponding index in the array PARAM::key. This index is returned
    through the variable param_idx, to be used later as argument of
    check_quick_select().

  RETURN
    Pointer to the SEL_ARG subtree that corresponds to index.
*/

SEL_ARG * get_index_range_tree(uint index, SEL_TREE* range_tree, PARAM *param,
                               uint *param_idx)
{
  uint idx= 0; /* Index nr in param->key_parts */
  while (idx < param->keys)
  {
    if (index == param->real_keynr[idx])
      break;
    idx++;
  }
  *param_idx= idx;
  return(range_tree->keys[idx]);
}


9878
/*
9879
  Compute the cost of a quick_group_min_max_select for a particular index.
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  SYNOPSIS
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    cost_group_min_max()
    table                [in] The table being accessed
    index_info           [in] The index used to access the table
    used_key_parts       [in] Number of key parts used to access the index
    group_key_parts      [in] Number of index key parts in the group prefix
    range_tree           [in] Tree of ranges for all indexes
    index_tree           [in] The range tree for the current index
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    quick_prefix_records [in] Number of records retrieved by the internally
			      used quick range select if any
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    have_min             [in] True if there is a MIN function
    have_max             [in] True if there is a MAX function
    read_cost           [out] The cost to retrieve rows via this quick select
    records             [out] The number of rows retrieved
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  DESCRIPTION
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    This method computes the access cost of a TRP_GROUP_MIN_MAX instance and
    the number of rows returned. It updates this->read_cost and this->records.
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  NOTES
    The cost computation distinguishes several cases:
    1) No equality predicates over non-group attributes (thus no key_infix).
       If groups are bigger than blocks on the average, then we assume that it
       is very unlikely that block ends are aligned with group ends, thus even
       if we look for both MIN and MAX keys, all pairs of neighbor MIN/MAX
       keys, except for the first MIN and the last MAX keys, will be in the
       same block.  If groups are smaller than blocks, then we are going to
       read all blocks.
    2) There are equality predicates over non-group attributes.
       In this case the group prefix is extended by additional constants, and
       as a result the min/max values are inside sub-groups of the original
       groups. The number of blocks that will be read depends on whether the
       ends of these sub-groups will be contained in the same or in different
       blocks. We compute the probability for the two ends of a subgroup to be
       in two different blocks as the ratio of:
       - the number of positions of the left-end of a subgroup inside a group,
         such that the right end of the subgroup is past the end of the buffer
         containing the left-end, and
       - the total number of possible positions for the left-end of the
         subgroup, which is the number of keys in the containing group.
       We assume it is very unlikely that two ends of subsequent subgroups are
       in the same block.
    3) The are range predicates over the group attributes.
       Then some groups may be filtered by the range predicates. We use the
       selectivity of the range predicates to decide how many groups will be
       filtered.

  TODO
     - Take into account the optional range predicates over the MIN/MAX
       argument.
     - Check if we have a PK index and we use all cols - then each key is a
       group, and it will be better to use an index scan.

  RETURN
    None
*/

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void cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts,
                        uint group_key_parts, SEL_TREE *range_tree,
                        SEL_ARG *index_tree, ha_rows quick_prefix_records,
                        bool have_min, bool have_max,
                        double *read_cost, ha_rows *records)
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{
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  ha_rows table_records;
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  uint num_groups;
  uint num_blocks;
  uint keys_per_block;
  uint keys_per_group;
  uint keys_per_subgroup; /* Average number of keys in sub-groups */
                          /* formed by a key infix. */
  double p_overlap; /* Probability that a sub-group overlaps two blocks. */
  double quick_prefix_selectivity;
  double io_cost;
  double cpu_cost= 0; /* TODO: CPU cost of index_read calls? */
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  DBUG_ENTER("cost_group_min_max");
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  table_records= table->file->stats.records;
  keys_per_block= (table->file->stats.block_size / 2 /
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                   (index_info->key_length + table->file->ref_length)
                        + 1);
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  num_blocks= (uint)(table_records / keys_per_block) + 1;
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  /* Compute the number of keys in a group. */
  keys_per_group= index_info->rec_per_key[group_key_parts - 1];
  if (keys_per_group == 0) /* If there is no statistics try to guess */
    /* each group contains 10% of all records */
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    keys_per_group= (uint)(table_records / 10) + 1;
  num_groups= (uint)(table_records / keys_per_group) + 1;
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  /* Apply the selectivity of the quick select for group prefixes. */
  if (range_tree && (quick_prefix_records != HA_POS_ERROR))
  {
    quick_prefix_selectivity= (double) quick_prefix_records /
                              (double) table_records;
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    num_groups= (uint) rint(num_groups * quick_prefix_selectivity);
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    set_if_bigger(num_groups, 1);
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  }

  if (used_key_parts > group_key_parts)
  { /*
      Compute the probability that two ends of a subgroup are inside
      different blocks.
    */
    keys_per_subgroup= index_info->rec_per_key[used_key_parts - 1];
    if (keys_per_subgroup >= keys_per_block) /* If a subgroup is bigger than */
      p_overlap= 1.0;       /* a block, it will overlap at least two blocks. */
    else
    {
      double blocks_per_group= (double) num_blocks / (double) num_groups;
      p_overlap= (blocks_per_group * (keys_per_subgroup - 1)) / keys_per_group;
      p_overlap= min(p_overlap, 1.0);
    }
    io_cost= (double) min(num_groups * (1 + p_overlap), num_blocks);
  }
  else
    io_cost= (keys_per_group > keys_per_block) ?
             (have_min && have_max) ? (double) (num_groups + 1) :
                                      (double) num_groups :
             (double) num_blocks;

  /*
    TODO: If there is no WHERE clause and no other expressions, there should be
    no CPU cost. We leave it here to make this cost comparable to that of index
    scan as computed in SQL_SELECT::test_quick_select().
  */
  cpu_cost= (double) num_groups / TIME_FOR_COMPARE;

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  *read_cost= io_cost + cpu_cost;
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  *records= num_groups;
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  DBUG_PRINT("info",
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             ("table rows: %lu  keys/block: %u  keys/group: %u  result rows: %lu  blocks: %u",
              (ulong)table_records, keys_per_block, keys_per_group, 
              (ulong) *records, num_blocks));
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  DBUG_VOID_RETURN;
}


/*
  Construct a new quick select object for queries with group by with min/max.

  SYNOPSIS
    TRP_GROUP_MIN_MAX::make_quick()
    param              Parameter from test_quick_select
    retrieve_full_rows ignored
    parent_alloc       Memory pool to use, if any.

  NOTES
    Make_quick ignores the retrieve_full_rows parameter because
    QUICK_GROUP_MIN_MAX_SELECT always performs 'index only' scans.
    The other parameter are ignored as well because all necessary
    data to create the QUICK object is computed at this TRP creation
    time.

  RETURN
    New QUICK_GROUP_MIN_MAX_SELECT object if successfully created,
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    NULL otherwise.
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*/

QUICK_SELECT_I *
TRP_GROUP_MIN_MAX::make_quick(PARAM *param, bool retrieve_full_rows,
                              MEM_ROOT *parent_alloc)
{
  QUICK_GROUP_MIN_MAX_SELECT *quick;
  DBUG_ENTER("TRP_GROUP_MIN_MAX::make_quick");

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  quick= new QUICK_GROUP_MIN_MAX_SELECT(param->table,
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                                        param->thd->lex->current_select->join,
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                                        have_min, have_max, min_max_arg_part,
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                                        group_prefix_len, group_key_parts,
                                        used_key_parts, index_info, index,
                                        read_cost, records, key_infix_len,
                                        key_infix, parent_alloc);
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  if (!quick)
    DBUG_RETURN(NULL);

  if (quick->init())
  {
    delete quick;
    DBUG_RETURN(NULL);
  }

  if (range_tree)
  {
    DBUG_ASSERT(quick_prefix_records > 0);
    if (quick_prefix_records == HA_POS_ERROR)
      quick->quick_prefix_select= NULL; /* Can't construct a quick select. */
    else
      /* Make a QUICK_RANGE_SELECT to be used for group prefix retrieval. */
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      quick->quick_prefix_select= get_quick_select(param, param_idx,
                                                   index_tree,
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                                                   &quick->alloc);

    /*
      Extract the SEL_ARG subtree that contains only ranges for the MIN/MAX
      attribute, and create an array of QUICK_RANGES to be used by the
      new quick select.
    */
    if (min_max_arg_part)
    {
      SEL_ARG *min_max_range= index_tree;
      while (min_max_range) /* Find the tree for the MIN/MAX key part. */
      {
        if (min_max_range->field->eq(min_max_arg_part->field))
          break;
        min_max_range= min_max_range->next_key_part;
      }
      /* Scroll to the leftmost interval for the MIN/MAX argument. */
      while (min_max_range && min_max_range->prev)
        min_max_range= min_max_range->prev;
      /* Create an array of QUICK_RANGEs for the MIN/MAX argument. */
      while (min_max_range)
      {
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        if (quick->add_range(min_max_range))
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        {
          delete quick;
          quick= NULL;
          DBUG_RETURN(NULL);
        }
        min_max_range= min_max_range->next;
      }
    }
  }
  else
    quick->quick_prefix_select= NULL;

  quick->update_key_stat();
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  quick->adjust_prefix_ranges();
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  DBUG_RETURN(quick);
}


/*
  Construct new quick select for group queries with min/max.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::QUICK_GROUP_MIN_MAX_SELECT()
    table             The table being accessed
    join              Descriptor of the current query
    have_min          TRUE if the query selects a MIN function
    have_max          TRUE if the query selects a MAX function
    min_max_arg_part  The only argument field of all MIN/MAX functions
    group_prefix_len  Length of all key parts in the group prefix
    prefix_key_parts  All key parts in the group prefix
    index_info        The index chosen for data access
    use_index         The id of index_info
    read_cost         Cost of this access method
    records           Number of records returned
    key_infix_len     Length of the key infix appended to the group prefix
    key_infix         Infix of constants from equality predicates
    parent_alloc      Memory pool for this and quick_prefix_select data

  RETURN
    None
*/

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QUICK_GROUP_MIN_MAX_SELECT::
QUICK_GROUP_MIN_MAX_SELECT(TABLE *table, JOIN *join_arg, bool have_min_arg,
                           bool have_max_arg,
                           KEY_PART_INFO *min_max_arg_part_arg,
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                           uint group_prefix_len_arg, uint group_key_parts_arg,
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                           uint used_key_parts_arg, KEY *index_info_arg,
                           uint use_index, double read_cost_arg,
                           ha_rows records_arg, uint key_infix_len_arg,
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                           uchar *key_infix_arg, MEM_ROOT *parent_alloc)
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  :join(join_arg), index_info(index_info_arg),
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   group_prefix_len(group_prefix_len_arg),
   group_key_parts(group_key_parts_arg), have_min(have_min_arg),
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   have_max(have_max_arg), seen_first_key(FALSE),
   min_max_arg_part(min_max_arg_part_arg), key_infix(key_infix_arg),
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   key_infix_len(key_infix_len_arg), min_functions_it(NULL),
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   max_functions_it(NULL)
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{
  head=       table;
  file=       head->file;
  index=      use_index;
  record=     head->record[0];
  tmp_record= head->record[1];
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  read_time= read_cost_arg;
  records= records_arg;
  used_key_parts= used_key_parts_arg;
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  real_key_parts= used_key_parts_arg;
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  real_prefix_len= group_prefix_len + key_infix_len;
  group_prefix= NULL;
  min_max_arg_len= min_max_arg_part ? min_max_arg_part->store_length : 0;
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  /*
    We can't have parent_alloc set as the init function can't handle this case
    yet.
  */
  DBUG_ASSERT(!parent_alloc);
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  if (!parent_alloc)
  {
    init_sql_alloc(&alloc, join->thd->variables.range_alloc_block_size, 0);
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    join->thd->mem_root= &alloc;
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  }
  else
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    bzero(&alloc, sizeof(MEM_ROOT));            // ensure that it's not used
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}


/*
  Do post-constructor initialization.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::init()
  
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  DESCRIPTION
    The method performs initialization that cannot be done in the constructor
    such as memory allocations that may fail. It allocates memory for the
    group prefix and inifix buffers, and for the lists of MIN/MAX item to be
    updated during execution.

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  RETURN
    0      OK
    other  Error code
*/

int QUICK_GROUP_MIN_MAX_SELECT::init()
{
  if (group_prefix) /* Already initialized. */
    return 0;

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  if (!(last_prefix= (uchar*) alloc_root(&alloc, group_prefix_len)))
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      return 1;
  /*
    We may use group_prefix to store keys with all select fields, so allocate
    enough space for it.
  */
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  if (!(group_prefix= (uchar*) alloc_root(&alloc,
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                                         real_prefix_len + min_max_arg_len)))
    return 1;

  if (key_infix_len > 0)
  {
    /*
      The memory location pointed to by key_infix will be deleted soon, so
      allocate a new buffer and copy the key_infix into it.
    */
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    uchar *tmp_key_infix= (uchar*) alloc_root(&alloc, key_infix_len);
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    if (!tmp_key_infix)
      return 1;
    memcpy(tmp_key_infix, this->key_infix, key_infix_len);
    this->key_infix= tmp_key_infix;
  }

  if (min_max_arg_part)
  {
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    if (my_init_dynamic_array(&min_max_ranges, sizeof(QUICK_RANGE*), 16, 16))
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      return 1;

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    if (have_min)
    {
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      if (!(min_functions= new List<Item_sum>))
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        return 1;
    }
    else
      min_functions= NULL;
    if (have_max)
    {
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      if (!(max_functions= new List<Item_sum>))
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        return 1;
    }
    else
      max_functions= NULL;
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    Item_sum *min_max_item;
    Item_sum **func_ptr= join->sum_funcs;
    while ((min_max_item= *(func_ptr++)))
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    {
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      if (have_min && (min_max_item->sum_func() == Item_sum::MIN_FUNC))
        min_functions->push_back(min_max_item);
      else if (have_max && (min_max_item->sum_func() == Item_sum::MAX_FUNC))
        max_functions->push_back(min_max_item);
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    }

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    if (have_min)
    {
      if (!(min_functions_it= new List_iterator<Item_sum>(*min_functions)))
        return 1;
    }

    if (have_max)
    {
      if (!(max_functions_it= new List_iterator<Item_sum>(*max_functions)))
        return 1;
    }
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  }
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  else
    min_max_ranges.elements= 0;
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  return 0;
}


QUICK_GROUP_MIN_MAX_SELECT::~QUICK_GROUP_MIN_MAX_SELECT()
{
  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::~QUICK_GROUP_MIN_MAX_SELECT");
  if (file->inited != handler::NONE) 
    file->ha_index_end();
  if (min_max_arg_part)
    delete_dynamic(&min_max_ranges);
  free_root(&alloc,MYF(0));
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  delete min_functions_it;
  delete max_functions_it;
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  delete quick_prefix_select;
  DBUG_VOID_RETURN; 
}


/*
  Eventually create and add a new quick range object.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::add_range()
    sel_range  Range object from which a 

  NOTES
    Construct a new QUICK_RANGE object from a SEL_ARG object, and
    add it to the array min_max_ranges. If sel_arg is an infinite
    range, e.g. (x < 5 or x > 4), then skip it and do not construct
    a quick range.

  RETURN
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    FALSE on success
    TRUE  otherwise
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*/

bool QUICK_GROUP_MIN_MAX_SELECT::add_range(SEL_ARG *sel_range)
{
  QUICK_RANGE *range;
  uint range_flag= sel_range->min_flag | sel_range->max_flag;

  /* Skip (-inf,+inf) ranges, e.g. (x < 5 or x > 4). */
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  if ((range_flag & NO_MIN_RANGE) && (range_flag & NO_MAX_RANGE))
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    return FALSE;
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  if (!(sel_range->min_flag & NO_MIN_RANGE) &&
      !(sel_range->max_flag & NO_MAX_RANGE))
  {
    if (sel_range->maybe_null &&
        sel_range->min_value[0] && sel_range->max_value[0])
      range_flag|= NULL_RANGE; /* IS NULL condition */
    else if (memcmp(sel_range->min_value, sel_range->max_value,
                    min_max_arg_len) == 0)
      range_flag|= EQ_RANGE;  /* equality condition */
  }
  range= new QUICK_RANGE(sel_range->min_value, min_max_arg_len,
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                         make_keypart_map(sel_range->part),
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                         sel_range->max_value, min_max_arg_len,
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                         make_keypart_map(sel_range->part),
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                         range_flag);
  if (!range)
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    return TRUE;
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  if (insert_dynamic(&min_max_ranges, (uchar*)&range))
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    return TRUE;
  return FALSE;
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}


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/*
  Opens the ranges if there are more conditions in quick_prefix_select than
  the ones used for jumping through the prefixes.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges()

  NOTES
    quick_prefix_select is made over the conditions on the whole key.
    It defines a number of ranges of length x. 
    However when jumping through the prefixes we use only the the first 
    few most significant keyparts in the range key. However if there
    are more keyparts to follow the ones we are using we must make the 
    condition on the key inclusive (because x < "ab" means 
    x[0] < 'a' OR (x[0] == 'a' AND x[1] < 'b').
    To achive the above we must turn off the NEAR_MIN/NEAR_MAX
*/
void QUICK_GROUP_MIN_MAX_SELECT::adjust_prefix_ranges ()
{
  if (quick_prefix_select &&
      group_prefix_len < quick_prefix_select->max_used_key_length)
  {
    DYNAMIC_ARRAY *arr;
    uint inx;

    for (inx= 0, arr= &quick_prefix_select->ranges; inx < arr->elements; inx++)
    {
      QUICK_RANGE *range;

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      get_dynamic(arr, (uchar*)&range, inx);
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      range->flag &= ~(NEAR_MIN | NEAR_MAX);
    }
  }
}


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/*
  Determine the total number and length of the keys that will be used for
  index lookup.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::update_key_stat()

  DESCRIPTION
    The total length of the keys used for index lookup depends on whether
    there are any predicates referencing the min/max argument, and/or if
    the min/max argument field can be NULL.
    This function does an optimistic analysis whether the search key might
    be extended by a constant for the min/max keypart. It is 'optimistic'
    because during actual execution it may happen that a particular range
    is skipped, and then a shorter key will be used. However this is data
    dependent and can't be easily estimated here.

  RETURN
    None
*/

void QUICK_GROUP_MIN_MAX_SELECT::update_key_stat()
{
  max_used_key_length= real_prefix_len;
  if (min_max_ranges.elements > 0)
  {
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    QUICK_RANGE *cur_range;
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    if (have_min)
    { /* Check if the right-most range has a lower boundary. */
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      get_dynamic(&min_max_ranges, (uchar*)&cur_range,
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                  min_max_ranges.elements - 1);
      if (!(cur_range->flag & NO_MIN_RANGE))
      {
        max_used_key_length+= min_max_arg_len;
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        used_key_parts++;
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        return;
      }
    }
    if (have_max)
    { /* Check if the left-most range has an upper boundary. */
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      get_dynamic(&min_max_ranges, (uchar*)&cur_range, 0);
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      if (!(cur_range->flag & NO_MAX_RANGE))
      {
        max_used_key_length+= min_max_arg_len;
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        used_key_parts++;
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        return;
      }
    }
  }
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  else if (have_min && min_max_arg_part &&
           min_max_arg_part->field->real_maybe_null())
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  {
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    /*
      If a MIN/MAX argument value is NULL, we can quickly determine
      that we're in the beginning of the next group, because NULLs
      are always < any other value. This allows us to quickly
      determine the end of the current group and jump to the next
      group (see next_min()) and thus effectively increases the
      usable key length.
    */
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    max_used_key_length+= min_max_arg_len;
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    used_key_parts++;
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  }
}


/*
  Initialize a quick group min/max select for key retrieval.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::reset()

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  DESCRIPTION
    Initialize the index chosen for access and find and store the prefix
    of the last group. The method is expensive since it performs disk access.

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  RETURN
    0      OK
    other  Error code
*/

int QUICK_GROUP_MIN_MAX_SELECT::reset(void)
{
  int result;
  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::reset");

  file->extra(HA_EXTRA_KEYREAD); /* We need only the key attributes */
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  if ((result= file->ha_index_init(index,1)))
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    DBUG_RETURN(result);
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  if (quick_prefix_select && quick_prefix_select->reset())
    DBUG_RETURN(1);
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  result= file->index_last(record);
  if (result == HA_ERR_END_OF_FILE)
    DBUG_RETURN(0);
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  /* Save the prefix of the last group. */
  key_copy(last_prefix, record, index_info, group_prefix_len);

  DBUG_RETURN(0);
}



/* 
  Get the next key containing the MIN and/or MAX key for the next group.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::get_next()

  DESCRIPTION
    The method finds the next subsequent group of records that satisfies the
    query conditions and finds the keys that contain the MIN/MAX values for
    the key part referenced by the MIN/MAX function(s). Once a group and its
    MIN/MAX values are found, store these values in the Item_sum objects for
    the MIN/MAX functions. The rest of the values in the result row are stored
    in the Item_field::result_field of each select field. If the query does
    not contain MIN and/or MAX functions, then the function only finds the
    group prefix, which is a query answer itself.

  NOTES
    If both MIN and MAX are computed, then we use the fact that if there is
    no MIN key, there can't be a MAX key as well, so we can skip looking
    for a MAX key in this case.

  RETURN
    0                  on success
    HA_ERR_END_OF_FILE if returned all keys
    other              if some error occurred
*/

int QUICK_GROUP_MIN_MAX_SELECT::get_next()
{
  int min_res= 0;
  int max_res= 0;
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#ifdef HPUX11
  /*
    volatile is required by a bug in the HP compiler due to which the
    last test of result fails.
  */
  volatile int result;
#else
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  int result;
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#endif
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  int is_last_prefix= 0;
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  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::get_next");

  /*
    Loop until a group is found that satisfies all query conditions or the last
    group is reached.
  */
  do
  {
    result= next_prefix();
    /*
      Check if this is the last group prefix. Notice that at this point
      this->record contains the current prefix in record format.
    */
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    if (!result)
    {
      is_last_prefix= key_cmp(index_info->key_part, last_prefix,
                              group_prefix_len);
      DBUG_ASSERT(is_last_prefix <= 0);
    }
    else 
    {
      if (result == HA_ERR_KEY_NOT_FOUND)
        continue;
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      break;
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    }
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    if (have_min)
    {
      min_res= next_min();
      if (min_res == 0)
        update_min_result();
    }
    /* If there is no MIN in the group, there is no MAX either. */
    if ((have_max && !have_min) ||
        (have_max && have_min && (min_res == 0)))
    {
      max_res= next_max();
      if (max_res == 0)
        update_max_result();
      /* If a MIN was found, a MAX must have been found as well. */
      DBUG_ASSERT((have_max && !have_min) ||
                  (have_max && have_min && (max_res == 0)));
    }
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    /*
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      If this is just a GROUP BY or DISTINCT without MIN or MAX and there
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      are equality predicates for the key parts after the group, find the
      first sub-group with the extended prefix.
    */
    if (!have_min && !have_max && key_infix_len > 0)
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      result= file->index_read_map(record, group_prefix,
                                   make_prev_keypart_map(real_key_parts),
                                   HA_READ_KEY_EXACT);
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    result= have_min ? min_res : have_max ? max_res : result;
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  } while ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) &&
           is_last_prefix != 0);
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  if (result == 0)
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  {
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    /*
      Partially mimic the behavior of end_select_send. Copy the
      field data from Item_field::field into Item_field::result_field
      of each non-aggregated field (the group fields, and optionally
      other fields in non-ANSI SQL mode).
    */
    copy_fields(&join->tmp_table_param);
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  }
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  else if (result == HA_ERR_KEY_NOT_FOUND)
    result= HA_ERR_END_OF_FILE;

  DBUG_RETURN(result);
}


/*
  Retrieve the minimal key in the next group.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::next_min()

  DESCRIPTION
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    Find the minimal key within this group such that the key satisfies the query
    conditions and NULL semantics. The found key is loaded into this->record.
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  IMPLEMENTATION
    Depending on the values of min_max_ranges.elements, key_infix_len, and
    whether there is a  NULL in the MIN field, this function may directly
    return without any data access. In this case we use the key loaded into
    this->record by the call to this->next_prefix() just before this call.

  RETURN
    0                    on success
    HA_ERR_KEY_NOT_FOUND if no MIN key was found that fulfills all conditions.
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    HA_ERR_END_OF_FILE   - "" -
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    other                if some error occurred
*/

int QUICK_GROUP_MIN_MAX_SELECT::next_min()
{
  int result= 0;
  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_min");

  /* Find the MIN key using the eventually extended group prefix. */
  if (min_max_ranges.elements > 0)
  {
    if ((result= next_min_in_range()))
      DBUG_RETURN(result);
  }
  else
  {
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    /* Apply the constant equality conditions to the non-group select fields */
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    if (key_infix_len > 0)
    {
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      if ((result= file->index_read_map(record, group_prefix,
                                        make_prev_keypart_map(real_key_parts),
                                        HA_READ_KEY_EXACT)))
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        DBUG_RETURN(result);
    }

    /*
      If the min/max argument field is NULL, skip subsequent rows in the same
      group with NULL in it. Notice that:
      - if the first row in a group doesn't have a NULL in the field, no row
      in the same group has (because NULL < any other value),
      - min_max_arg_part->field->ptr points to some place in 'record'.
    */
    if (min_max_arg_part && min_max_arg_part->field->is_null())
    {
      /* Find the first subsequent record without NULL in the MIN/MAX field. */
      key_copy(tmp_record, record, index_info, 0);
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      result= file->index_read_map(record, tmp_record,
                                   make_keypart_map(real_key_parts),
                                   HA_READ_AFTER_KEY);
10655 10656 10657 10658 10659 10660 10661 10662 10663 10664 10665 10666
      /*
        Check if the new record belongs to the current group by comparing its
        prefix with the group's prefix. If it is from the next group, then the
        whole group has NULLs in the MIN/MAX field, so use the first record in
        the group as a result.
        TODO:
        It is possible to reuse this new record as the result candidate for the
        next call to next_min(), and to save one lookup in the next call. For
        this add a new member 'this->next_group_prefix'.
      */
      if (!result)
      {
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        if (key_cmp(index_info->key_part, group_prefix, real_prefix_len))
10668
          key_restore(record, tmp_record, index_info, 0);
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      }
10670
      else if (result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE)
10671 10672 10673 10674 10675 10676 10677 10678 10679 10680 10681 10682 10683 10684 10685 10686 10687 10688 10689
        result= 0; /* There is a result in any case. */
    }
  }

  /*
    If the MIN attribute is non-nullable, this->record already contains the
    MIN key in the group, so just return.
  */
  DBUG_RETURN(result);
}


/* 
  Retrieve the maximal key in the next group.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::next_max()

  DESCRIPTION
10690
    Lookup the maximal key of the group, and store it into this->record.
10691 10692 10693 10694

  RETURN
    0                    on success
    HA_ERR_KEY_NOT_FOUND if no MAX key was found that fulfills all conditions.
10695
    HA_ERR_END_OF_FILE	 - "" -
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    other                if some error occurred
*/

int QUICK_GROUP_MIN_MAX_SELECT::next_max()
{
  int result;

  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_max");

  /* Get the last key in the (possibly extended) group. */
  if (min_max_ranges.elements > 0)
    result= next_max_in_range();
  else
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    result= file->index_read_map(record, group_prefix,
                                 make_prev_keypart_map(real_key_parts),
                                 HA_READ_PREFIX_LAST);
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  DBUG_RETURN(result);
}


/*
  Determine the prefix of the next group.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::next_prefix()

  DESCRIPTION
    Determine the prefix of the next group that satisfies the query conditions.
    If there is a range condition referencing the group attributes, use a
    QUICK_RANGE_SELECT object to retrieve the *first* key that satisfies the
    condition. If there is a key infix of constants, append this infix
    immediately after the group attributes. The possibly extended prefix is
    stored in this->group_prefix. The first key of the found group is stored in
    this->record, on which relies this->next_min().

  RETURN
    0                    on success
    HA_ERR_KEY_NOT_FOUND if there is no key with the formed prefix
    HA_ERR_END_OF_FILE   if there are no more keys
    other                if some error occurred
*/
int QUICK_GROUP_MIN_MAX_SELECT::next_prefix()
{
  int result;
  DBUG_ENTER("QUICK_GROUP_MIN_MAX_SELECT::next_prefix");

  if (quick_prefix_select)
  {
10744
    uchar *cur_prefix= seen_first_key ? group_prefix : NULL;
10745
    if ((result= quick_prefix_select->get_next_prefix(group_prefix_len,
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10746
                         make_prev_keypart_map(group_key_parts), cur_prefix)))
10747 10748 10749 10750 10751 10752 10753 10754 10755 10756 10757 10758 10759 10760 10761
      DBUG_RETURN(result);
    seen_first_key= TRUE;
  }
  else
  {
    if (!seen_first_key)
    {
      result= file->index_first(record);
      if (result)
        DBUG_RETURN(result);
      seen_first_key= TRUE;
    }
    else
    {
      /* Load the first key in this group into record. */
10762 10763 10764
      result= file->index_read_map(record, group_prefix,
                                   make_prev_keypart_map(group_key_parts),
                                   HA_READ_AFTER_KEY);
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      if (result)
        DBUG_RETURN(result);
    }
  }

  /* Save the prefix of this group for subsequent calls. */
  key_copy(group_prefix, record, index_info, group_prefix_len);
  /* Append key_infix to group_prefix. */
  if (key_infix_len > 0)
    memcpy(group_prefix + group_prefix_len,
           key_infix, key_infix_len);

  DBUG_RETURN(0);
}


/*
  Find the minimal key in a group that satisfies some range conditions for the
  min/max argument field.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::next_min_in_range()

  DESCRIPTION
    Given the sequence of ranges min_max_ranges, find the minimal key that is
    in the left-most possible range. If there is no such key, then the current
    group does not have a MIN key that satisfies the WHERE clause. If a key is
    found, its value is stored in this->record.

  RETURN
    0                    on success
    HA_ERR_KEY_NOT_FOUND if there is no key with the given prefix in any of
                         the ranges
10798
    HA_ERR_END_OF_FILE   - "" -
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    other                if some error
*/

int QUICK_GROUP_MIN_MAX_SELECT::next_min_in_range()
{
  ha_rkey_function find_flag;
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  key_part_map keypart_map;
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  QUICK_RANGE *cur_range;
  bool found_null= FALSE;
  int result= HA_ERR_KEY_NOT_FOUND;

  DBUG_ASSERT(min_max_ranges.elements > 0);

  for (uint range_idx= 0; range_idx < min_max_ranges.elements; range_idx++)
  { /* Search from the left-most range to the right. */
10814
    get_dynamic(&min_max_ranges, (uchar*)&cur_range, range_idx);
10815 10816 10817 10818 10819 10820

    /*
      If the current value for the min/max argument is bigger than the right
      boundary of cur_range, there is no need to check this range.
    */
    if (range_idx != 0 && !(cur_range->flag & NO_MAX_RANGE) &&
10821
        (key_cmp(min_max_arg_part, (const uchar*) cur_range->max_key,
10822
                 min_max_arg_len) == 1))
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      continue;

    if (cur_range->flag & NO_MIN_RANGE)
    {
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      keypart_map= make_prev_keypart_map(real_key_parts);
10828
      find_flag= HA_READ_KEY_EXACT;
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    }
    else
    {
      /* Extend the search key with the lower boundary for this range. */
      memcpy(group_prefix + real_prefix_len, cur_range->min_key,
             cur_range->min_length);
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      keypart_map= make_keypart_map(real_key_parts);
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      find_flag= (cur_range->flag & (EQ_RANGE | NULL_RANGE)) ?
                 HA_READ_KEY_EXACT : (cur_range->flag & NEAR_MIN) ?
                 HA_READ_AFTER_KEY : HA_READ_KEY_OR_NEXT;
    }

10841
    result= file->index_read_map(record, group_prefix, keypart_map, find_flag);
10842
    if (result)
10843
    {
10844 10845 10846 10847
      if ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) &&
          (cur_range->flag & (EQ_RANGE | NULL_RANGE)))
        continue; /* Check the next range. */

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      /*
        In all other cases (HA_ERR_*, HA_READ_KEY_EXACT with NO_MIN_RANGE,
        HA_READ_AFTER_KEY, HA_READ_KEY_OR_NEXT) if the lookup failed for this
        range, it can't succeed for any other subsequent range.
      */
10853
      break;
10854
    }
10855 10856 10857 10858 10859 10860

    /* A key was found. */
    if (cur_range->flag & EQ_RANGE)
      break; /* No need to perform the checks below for equal keys. */

    if (cur_range->flag & NULL_RANGE)
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    {
      /*
        Remember this key, and continue looking for a non-NULL key that
        satisfies some other condition.
      */
      memcpy(tmp_record, record, head->s->rec_buff_length);
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      found_null= TRUE;
      continue;
    }

    /* Check if record belongs to the current group. */
    if (key_cmp(index_info->key_part, group_prefix, real_prefix_len))
    {
10874
      result= HA_ERR_KEY_NOT_FOUND;
10875 10876 10877 10878 10879 10880 10881
      continue;
    }

    /* If there is an upper limit, check if the found key is in the range. */
    if ( !(cur_range->flag & NO_MAX_RANGE) )
    {
      /* Compose the MAX key for the range. */
10882
      uchar *max_key= (uchar*) my_alloca(real_prefix_len + min_max_arg_len);
10883 10884 10885 10886 10887 10888 10889 10890 10891
      memcpy(max_key, group_prefix, real_prefix_len);
      memcpy(max_key + real_prefix_len, cur_range->max_key,
             cur_range->max_length);
      /* Compare the found key with max_key. */
      int cmp_res= key_cmp(index_info->key_part, max_key,
                           real_prefix_len + min_max_arg_len);
      if (!((cur_range->flag & NEAR_MAX) && (cmp_res == -1) ||
            (cmp_res <= 0)))
      {
10892
        result= HA_ERR_KEY_NOT_FOUND;
10893 10894 10895 10896 10897 10898 10899 10900 10901 10902 10903 10904 10905 10906
        continue;
      }
    }
    /* If we got to this point, the current key qualifies as MIN. */
    DBUG_ASSERT(result == 0);
    break;
  }
  /*
    If there was a key with NULL in the MIN/MAX field, and there was no other
    key without NULL from the same group that satisfies some other condition,
    then use the key with the NULL.
  */
  if (found_null && result)
  {
10907
    memcpy(record, tmp_record, head->s->rec_buff_length);
10908 10909 10910 10911 10912 10913 10914 10915 10916 10917 10918 10919 10920 10921 10922 10923 10924 10925 10926 10927 10928 10929 10930
    result= 0;
  }
  return result;
}


/*
  Find the maximal key in a group that satisfies some range conditions for the
  min/max argument field.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::next_max_in_range()

  DESCRIPTION
    Given the sequence of ranges min_max_ranges, find the maximal key that is
    in the right-most possible range. If there is no such key, then the current
    group does not have a MAX key that satisfies the WHERE clause. If a key is
    found, its value is stored in this->record.

  RETURN
    0                    on success
    HA_ERR_KEY_NOT_FOUND if there is no key with the given prefix in any of
                         the ranges
10931
    HA_ERR_END_OF_FILE   - "" -
10932 10933 10934 10935 10936 10937
    other                if some error
*/

int QUICK_GROUP_MIN_MAX_SELECT::next_max_in_range()
{
  ha_rkey_function find_flag;
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  key_part_map keypart_map;
10939 10940 10941 10942 10943 10944 10945
  QUICK_RANGE *cur_range;
  int result;

  DBUG_ASSERT(min_max_ranges.elements > 0);

  for (uint range_idx= min_max_ranges.elements; range_idx > 0; range_idx--)
  { /* Search from the right-most range to the left. */
10946
    get_dynamic(&min_max_ranges, (uchar*)&cur_range, range_idx - 1);
10947 10948 10949 10950 10951 10952 10953

    /*
      If the current value for the min/max argument is smaller than the left
      boundary of cur_range, there is no need to check this range.
    */
    if (range_idx != min_max_ranges.elements &&
        !(cur_range->flag & NO_MIN_RANGE) &&
10954
        (key_cmp(min_max_arg_part, (const uchar*) cur_range->min_key,
10955
                 min_max_arg_len) == -1))
10956 10957 10958 10959
      continue;

    if (cur_range->flag & NO_MAX_RANGE)
    {
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      keypart_map= make_prev_keypart_map(real_key_parts);
10961
      find_flag= HA_READ_PREFIX_LAST;
10962 10963 10964 10965 10966 10967
    }
    else
    {
      /* Extend the search key with the upper boundary for this range. */
      memcpy(group_prefix + real_prefix_len, cur_range->max_key,
             cur_range->max_length);
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      keypart_map= make_keypart_map(real_key_parts);
10969 10970 10971 10972 10973
      find_flag= (cur_range->flag & EQ_RANGE) ?
                 HA_READ_KEY_EXACT : (cur_range->flag & NEAR_MAX) ?
                 HA_READ_BEFORE_KEY : HA_READ_PREFIX_LAST_OR_PREV;
    }

10974
    result= file->index_read_map(record, group_prefix, keypart_map, find_flag);
10975

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    if (result)
    {
10978 10979 10980 10981
      if ((result == HA_ERR_KEY_NOT_FOUND || result == HA_ERR_END_OF_FILE) &&
          (cur_range->flag & EQ_RANGE))
        continue; /* Check the next range. */

10982 10983 10984 10985 10986
      /*
        In no key was found with this upper bound, there certainly are no keys
        in the ranges to the left.
      */
      return result;
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10987
    }
10988 10989
    /* A key was found. */
    if (cur_range->flag & EQ_RANGE)
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      return 0; /* No need to perform the checks below for equal keys. */
10991 10992 10993

    /* Check if record belongs to the current group. */
    if (key_cmp(index_info->key_part, group_prefix, real_prefix_len))
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      continue;                                 // Row not found
10995 10996 10997 10998 10999

    /* If there is a lower limit, check if the found key is in the range. */
    if ( !(cur_range->flag & NO_MIN_RANGE) )
    {
      /* Compose the MIN key for the range. */
11000
      uchar *min_key= (uchar*) my_alloca(real_prefix_len + min_max_arg_len);
11001 11002 11003 11004 11005 11006 11007 11008 11009 11010 11011 11012 11013 11014 11015 11016 11017 11018 11019 11020 11021 11022 11023 11024 11025 11026 11027 11028 11029 11030 11031 11032 11033 11034 11035 11036 11037 11038 11039 11040 11041 11042 11043 11044 11045 11046 11047 11048 11049 11050 11051 11052 11053 11054 11055 11056 11057 11058 11059 11060 11061 11062 11063 11064 11065 11066 11067 11068 11069 11070 11071 11072 11073 11074 11075 11076 11077 11078 11079 11080 11081 11082
      memcpy(min_key, group_prefix, real_prefix_len);
      memcpy(min_key + real_prefix_len, cur_range->min_key,
             cur_range->min_length);
      /* Compare the found key with min_key. */
      int cmp_res= key_cmp(index_info->key_part, min_key,
                           real_prefix_len + min_max_arg_len);
      if (!((cur_range->flag & NEAR_MIN) && (cmp_res == 1) ||
            (cmp_res >= 0)))
        continue;
    }
    /* If we got to this point, the current key qualifies as MAX. */
    return result;
  }
  return HA_ERR_KEY_NOT_FOUND;
}


/*
  Update all MIN function results with the newly found value.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::update_min_result()

  DESCRIPTION
    The method iterates through all MIN functions and updates the result value
    of each function by calling Item_sum::reset(), which in turn picks the new
    result value from this->head->record[0], previously updated by
    next_min(). The updated value is stored in a member variable of each of the
    Item_sum objects, depending on the value type.

  IMPLEMENTATION
    The update must be done separately for MIN and MAX, immediately after
    next_min() was called and before next_max() is called, because both MIN and
    MAX take their result value from the same buffer this->head->record[0]
    (i.e.  this->record).

  RETURN
    None
*/

void QUICK_GROUP_MIN_MAX_SELECT::update_min_result()
{
  Item_sum *min_func;

  min_functions_it->rewind();
  while ((min_func= (*min_functions_it)++))
    min_func->reset();
}


/*
  Update all MAX function results with the newly found value.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::update_max_result()

  DESCRIPTION
    The method iterates through all MAX functions and updates the result value
    of each function by calling Item_sum::reset(), which in turn picks the new
    result value from this->head->record[0], previously updated by
    next_max(). The updated value is stored in a member variable of each of the
    Item_sum objects, depending on the value type.

  IMPLEMENTATION
    The update must be done separately for MIN and MAX, immediately after
    next_max() was called, because both MIN and MAX take their result value
    from the same buffer this->head->record[0] (i.e.  this->record).

  RETURN
    None
*/

void QUICK_GROUP_MIN_MAX_SELECT::update_max_result()
{
  Item_sum *max_func;

  max_functions_it->rewind();
  while ((max_func= (*max_functions_it)++))
    max_func->reset();
}


11083 11084 11085 11086 11087 11088 11089 11090 11091 11092 11093 11094 11095 11096 11097
/*
  Append comma-separated list of keys this quick select uses to key_names;
  append comma-separated list of corresponding used lengths to used_lengths.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::add_keys_and_lengths()
    key_names    [out] Names of used indexes
    used_lengths [out] Corresponding lengths of the index names

  DESCRIPTION
    This method is used by select_describe to extract the names of the
    indexes used by a quick select.

*/

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void QUICK_GROUP_MIN_MAX_SELECT::add_keys_and_lengths(String *key_names,
                                                      String *used_lengths)
{
  char buf[64];
  uint length;
  key_names->append(index_info->name);
  length= longlong2str(max_used_key_length, buf, 10) - buf;
  used_lengths->append(buf, length);
}


11109
#ifndef DBUG_OFF
11110

11111 11112 11113 11114 11115 11116 11117
static void print_sel_tree(PARAM *param, SEL_TREE *tree, key_map *tree_map,
                           const char *msg)
{
  SEL_ARG **key,**end;
  int idx;
  char buff[1024];
  DBUG_ENTER("print_sel_tree");
11118

11119 11120 11121 11122 11123 11124 11125 11126 11127 11128 11129 11130 11131 11132 11133
  String tmp(buff,sizeof(buff),&my_charset_bin);
  tmp.length(0);
  for (idx= 0,key=tree->keys, end=key+param->keys ;
       key != end ;
       key++,idx++)
  {
    if (tree_map->is_set(idx))
    {
      uint keynr= param->real_keynr[idx];
      if (tmp.length())
        tmp.append(',');
      tmp.append(param->table->key_info[keynr].name);
    }
  }
  if (!tmp.length())
11134
    tmp.append(STRING_WITH_LEN("(empty)"));
11135

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  DBUG_PRINT("info", ("SEL_TREE: 0x%lx (%s)  scans: %s", (long) tree, msg, tmp.ptr()));
11137

11138 11139
  DBUG_VOID_RETURN;
}
11140

11141 11142 11143 11144

static void print_ror_scans_arr(TABLE *table, const char *msg,
                                struct st_ror_scan_info **start,
                                struct st_ror_scan_info **end)
11145
{
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11146
  DBUG_ENTER("print_ror_scans_arr");
11147 11148 11149 11150

  char buff[1024];
  String tmp(buff,sizeof(buff),&my_charset_bin);
  tmp.length(0);
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  for (;start != end; start++)
11152
  {
11153 11154 11155
    if (tmp.length())
      tmp.append(',');
    tmp.append(table->key_info[(*start)->keynr].name);
11156
  }
11157
  if (!tmp.length())
11158
    tmp.append(STRING_WITH_LEN("(empty)"));
11159 11160
  DBUG_PRINT("info", ("ROR key scans (%s): %s", msg, tmp.ptr()));
  DBUG_VOID_RETURN;
11161 11162
}

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11163 11164 11165 11166 11167 11168 11169 11170
/*****************************************************************************
** Print a quick range for debugging
** TODO:
** This should be changed to use a String to store each row instead
** of locking the DEBUG stream !
*****************************************************************************/

static void
11171
print_key(KEY_PART *key_part, const uchar *key, uint used_length)
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11172 11173
{
  char buff[1024];
11174
  const uchar *key_end= key+used_length;
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11175
  String tmp(buff,sizeof(buff),&my_charset_bin);
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  uint store_length;
11177
  TABLE *table= key_part->field->table;
11178 11179 11180
  my_bitmap_map *old_sets[2];

  dbug_tmp_use_all_columns(table, old_sets, table->read_set, table->write_set);
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11181

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11182
  for (; key < key_end; key+=store_length, key_part++)
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  {
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    Field *field=      key_part->field;
    store_length= key_part->store_length;

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11187 11188
    if (field->real_maybe_null())
    {
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11189
      if (*key)
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11190 11191 11192 11193
      {
	fwrite("NULL",sizeof(char),4,DBUG_FILE);
	continue;
      }
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11194 11195
      key++;					// Skip null byte
      store_length--;
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11196
    }
11197
    field->set_key_image(key, key_part->length);
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    if (field->type() == MYSQL_TYPE_BIT)
      (void) field->val_int_as_str(&tmp, 1);
    else
      field->val_str(&tmp);
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11202
    fwrite(tmp.ptr(),sizeof(char),tmp.length(),DBUG_FILE);
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11203 11204
    if (key+store_length < key_end)
      fputc('/',DBUG_FILE);
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11205
  }
11206
  dbug_tmp_restore_column_maps(table->read_set, table->write_set, old_sets);
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}

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11209

11210
static void print_quick(QUICK_SELECT_I *quick, const key_map *needed_reg)
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{
11212
  char buf[MAX_KEY/8+1];
11213
  TABLE *table;
11214
  my_bitmap_map *old_sets[2];
11215
  DBUG_ENTER("print_quick");
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11216
  if (!quick)
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    DBUG_VOID_RETURN;
11218
  DBUG_LOCK_FILE;
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11219

11220
  table= quick->head;
11221
  dbug_tmp_use_all_columns(table, old_sets, table->read_set, table->write_set);
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  quick->dbug_dump(0, TRUE);
11223
  dbug_tmp_restore_column_maps(table->read_set, table->write_set, old_sets);
11224

11225
  fprintf(DBUG_FILE,"other_keys: 0x%s:\n", needed_reg->print(buf));
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11226

11227
  DBUG_UNLOCK_FILE;
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  DBUG_VOID_RETURN;
}

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11231

11232 11233
void QUICK_RANGE_SELECT::dbug_dump(int indent, bool verbose)
{
11234
  /* purecov: begin inspected */
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  fprintf(DBUG_FILE, "%*squick range select, key %s, length: %d\n",
	  indent, "", head->key_info[index].name, max_used_key_length);
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  if (verbose)
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  {
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    QUICK_RANGE *range;
    QUICK_RANGE **pr= (QUICK_RANGE**)ranges.buffer;
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    QUICK_RANGE **end_range= pr + ranges.elements;
    for (; pr != end_range; ++pr)
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    {
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      fprintf(DBUG_FILE, "%*s", indent + 2, "");
      range= *pr;
      if (!(range->flag & NO_MIN_RANGE))
      {
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        print_key(key_parts, range->min_key, range->min_length);
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        if (range->flag & NEAR_MIN)
	  fputs(" < ",DBUG_FILE);
        else
	  fputs(" <= ",DBUG_FILE);
      }
      fputs("X",DBUG_FILE);
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      if (!(range->flag & NO_MAX_RANGE))
      {
        if (range->flag & NEAR_MAX)
	  fputs(" < ",DBUG_FILE);
        else
	  fputs(" <= ",DBUG_FILE);
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        print_key(key_parts, range->max_key, range->max_length);
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      }
      fputs("\n",DBUG_FILE);
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    }
  }
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  /* purecov: end */    
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}

void QUICK_INDEX_MERGE_SELECT::dbug_dump(int indent, bool verbose)
{
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  QUICK_RANGE_SELECT *quick;
  fprintf(DBUG_FILE, "%*squick index_merge select\n", indent, "");
  fprintf(DBUG_FILE, "%*smerged scans {\n", indent, "");
  while ((quick= it++))
    quick->dbug_dump(indent+2, verbose);
  if (pk_quick_select)
  {
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    fprintf(DBUG_FILE, "%*sclustered PK quick:\n", indent, "");
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    pk_quick_select->dbug_dump(indent+2, verbose);
  }
  fprintf(DBUG_FILE, "%*s}\n", indent, "");
}

void QUICK_ROR_INTERSECT_SELECT::dbug_dump(int indent, bool verbose)
{
  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
  QUICK_RANGE_SELECT *quick;
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  fprintf(DBUG_FILE, "%*squick ROR-intersect select, %scovering\n",
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          indent, "", need_to_fetch_row? "":"non-");
  fprintf(DBUG_FILE, "%*smerged scans {\n", indent, "");
  while ((quick= it++))
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    quick->dbug_dump(indent+2, verbose);
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  if (cpk_quick)
  {
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    fprintf(DBUG_FILE, "%*sclustered PK quick:\n", indent, "");
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    cpk_quick->dbug_dump(indent+2, verbose);
  }
  fprintf(DBUG_FILE, "%*s}\n", indent, "");
}

void QUICK_ROR_UNION_SELECT::dbug_dump(int indent, bool verbose)
{
  List_iterator_fast<QUICK_SELECT_I> it(quick_selects);
  QUICK_SELECT_I *quick;
  fprintf(DBUG_FILE, "%*squick ROR-union select\n", indent, "");
  fprintf(DBUG_FILE, "%*smerged scans {\n", indent, "");
  while ((quick= it++))
    quick->dbug_dump(indent+2, verbose);
  fprintf(DBUG_FILE, "%*s}\n", indent, "");
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}

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/*
  Print quick select information to DBUG_FILE.

  SYNOPSIS
    QUICK_GROUP_MIN_MAX_SELECT::dbug_dump()
    indent  Indentation offset
    verbose If TRUE show more detailed output.

  DESCRIPTION
    Print the contents of this quick select to DBUG_FILE. The method also
    calls dbug_dump() for the used quick select if any.

  IMPLEMENTATION
    Caller is responsible for locking DBUG_FILE before this call and unlocking
    it afterwards.

  RETURN
    None
*/

void QUICK_GROUP_MIN_MAX_SELECT::dbug_dump(int indent, bool verbose)
{
  fprintf(DBUG_FILE,
          "%*squick_group_min_max_select: index %s (%d), length: %d\n",
	  indent, "", index_info->name, index, max_used_key_length);
  if (key_infix_len > 0)
  {
    fprintf(DBUG_FILE, "%*susing key_infix with length %d:\n",
            indent, "", key_infix_len);
  }
  if (quick_prefix_select)
  {
    fprintf(DBUG_FILE, "%*susing quick_range_select:\n", indent, "");
    quick_prefix_select->dbug_dump(indent + 2, verbose);
  }
  if (min_max_ranges.elements > 0)
  {
    fprintf(DBUG_FILE, "%*susing %d quick_ranges for MIN/MAX:\n",
            indent, "", min_max_ranges.elements);
  }
}


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#endif /* NOT_USED */
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/*****************************************************************************
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** Instantiate templates 
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*****************************************************************************/

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#ifdef HAVE_EXPLICIT_TEMPLATE_INSTANTIATION
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template class List<QUICK_RANGE>;
template class List_iterator<QUICK_RANGE>;
#endif