sql_select.cc 298 KB
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/* Copyright (C) 2000-2004 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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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
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   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 */


/* mysql_select and join optimization */

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#ifdef USE_PRAGMA_IMPLEMENTATION
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#pragma implementation				// gcc: Class implementation
#endif
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#include "mysql_priv.h"
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#include "sql_select.h"
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#include <m_ctype.h>
#include <hash.h>
#include <ft_global.h>

const char *join_type_str[]={ "UNKNOWN","system","const","eq_ref","ref",
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			      "MAYBE_REF","ALL","range","index","fulltext",
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			      "ref_or_null","unique_subquery","index_subquery"
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};
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static void optimize_keyuse(JOIN *join, DYNAMIC_ARRAY *keyuse_array);
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static bool make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
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				 DYNAMIC_ARRAY *keyuse);
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static bool update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,
				JOIN_TAB *join_tab,
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                                uint tables, COND *conds,
				table_map table_map, SELECT_LEX *select_lex);
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static int sort_keyuse(KEYUSE *a,KEYUSE *b);
static void set_position(JOIN *join,uint index,JOIN_TAB *table,KEYUSE *key);
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static bool create_ref_for_key(JOIN *join, JOIN_TAB *j, KEYUSE *org_keyuse,
			       table_map used_tables);
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static void find_best_combination(JOIN *join,table_map rest_tables);
static void find_best(JOIN *join,table_map rest_tables,uint index,
		      double record_count,double read_time);
static uint cache_record_length(JOIN *join,uint index);
static double prev_record_reads(JOIN *join,table_map found_ref);
static bool get_best_combination(JOIN *join);
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static store_key *get_store_key(THD *thd,
				KEYUSE *keyuse, table_map used_tables,
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				KEY_PART_INFO *key_part, char *key_buff,
				uint maybe_null);
static bool make_simple_join(JOIN *join,TABLE *tmp_table);
static bool make_join_select(JOIN *join,SQL_SELECT *select,COND *item);
static void make_join_readinfo(JOIN *join,uint options);
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static bool only_eq_ref_tables(JOIN *join, ORDER *order, table_map tables);
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static void update_depend_map(JOIN *join);
static void update_depend_map(JOIN *join, ORDER *order);
static ORDER *remove_const(JOIN *join,ORDER *first_order,COND *cond,
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			   bool change_list, bool *simple_order);
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static int return_zero_rows(JOIN *join, select_result *res,TABLE_LIST *tables,
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			    List<Item> &fields, bool send_row,
			    uint select_options, const char *info,
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			    Item *having, Procedure *proc,
			    SELECT_LEX_UNIT *unit);
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static COND *optimize_cond(THD *thd, COND *conds,
			   Item::cond_result *cond_value);
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static bool const_expression_in_where(COND *conds,Item *item, Item **comp_item);
static bool open_tmp_table(TABLE *table);
static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,
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				    ulong options);
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static int do_select(JOIN *join,List<Item> *fields,TABLE *tmp_table,
		     Procedure *proc);
static int sub_select_cache(JOIN *join,JOIN_TAB *join_tab,bool end_of_records);
static int sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records);
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static int flush_cached_records(JOIN *join,JOIN_TAB *join_tab,bool skip_last);
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static int end_send(JOIN *join, JOIN_TAB *join_tab, bool end_of_records);
static int end_send_group(JOIN *join, JOIN_TAB *join_tab,bool end_of_records);
static int end_write(JOIN *join, JOIN_TAB *join_tab, bool end_of_records);
static int end_update(JOIN *join, JOIN_TAB *join_tab, bool end_of_records);
static int end_unique_update(JOIN *join,JOIN_TAB *join_tab,
			     bool end_of_records);
static int end_write_group(JOIN *join, JOIN_TAB *join_tab,
			   bool end_of_records);
static int test_if_group_changed(List<Item_buff> &list);
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static int join_read_const_table(JOIN_TAB *tab, POSITION *pos);
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static int join_read_system(JOIN_TAB *tab);
static int join_read_const(JOIN_TAB *tab);
static int join_read_key(JOIN_TAB *tab);
static int join_read_always_key(JOIN_TAB *tab);
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static int join_read_last_key(JOIN_TAB *tab);
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static int join_no_more_records(READ_RECORD *info);
static int join_read_next(READ_RECORD *info);
static int join_init_quick_read_record(JOIN_TAB *tab);
static int test_if_quick_select(JOIN_TAB *tab);
static int join_init_read_record(JOIN_TAB *tab);
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static int join_read_first(JOIN_TAB *tab);
static int join_read_next(READ_RECORD *info);
static int join_read_next_same(READ_RECORD *info);
static int join_read_last(JOIN_TAB *tab);
static int join_read_prev_same(READ_RECORD *info);
static int join_read_prev(READ_RECORD *info);
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static int join_ft_read_first(JOIN_TAB *tab);
static int join_ft_read_next(READ_RECORD *info);
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static int join_read_always_key_or_null(JOIN_TAB *tab);
static int join_read_next_same_or_null(READ_RECORD *info);
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static COND *make_cond_for_table(COND *cond,table_map table,
				 table_map used_table);
static Item* part_of_refkey(TABLE *form,Field *field);
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static uint find_shortest_key(TABLE *table, const key_map *usable_keys);
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static bool test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,
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				    ha_rows select_limit, bool no_changes);
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static bool list_contains_unique_index(TABLE *table,
                          bool (*find_func) (Field *, void *), void *data);
static bool find_field_in_item_list (Field *field, void *data);
static bool find_field_in_order_list (Field *field, void *data);
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static int create_sort_index(THD *thd, JOIN *join, ORDER *order,
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			     ha_rows filesort_limit, ha_rows select_limit);
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static int remove_duplicates(JOIN *join,TABLE *entry,List<Item> &fields,
			     Item *having);
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static int remove_dup_with_compare(THD *thd, TABLE *entry, Field **field,
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				   ulong offset,Item *having);
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static int remove_dup_with_hash_index(THD *thd,TABLE *table,
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				      uint field_count, Field **first_field,
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				      ulong key_length,Item *having);
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static int join_init_cache(THD *thd,JOIN_TAB *tables,uint table_count);
static ulong used_blob_length(CACHE_FIELD **ptr);
static bool store_record_in_cache(JOIN_CACHE *cache);
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static void reset_cache_read(JOIN_CACHE *cache);
static void reset_cache_write(JOIN_CACHE *cache);
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static void read_cached_record(JOIN_TAB *tab);
static bool cmp_buffer_with_ref(JOIN_TAB *tab);
static bool setup_new_fields(THD *thd,TABLE_LIST *tables,List<Item> &fields,
			     List<Item> &all_fields,ORDER *new_order);
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static ORDER *create_distinct_group(THD *thd, Item **ref_pointer_array,
                                    ORDER *order, List<Item> &fields,
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				    bool *all_order_by_fields_used);
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static bool test_if_subpart(ORDER *a,ORDER *b);
static TABLE *get_sort_by_table(ORDER *a,ORDER *b,TABLE_LIST *tables);
static void calc_group_buffer(JOIN *join,ORDER *group);
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static bool make_group_fields(JOIN *main_join, JOIN *curr_join);
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static bool alloc_group_fields(JOIN *join,ORDER *group);
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// Create list for using with tempory table
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static bool change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
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				     List<Item> &new_list1,
				     List<Item> &new_list2,
				     uint elements, List<Item> &items);
// Create list for using with tempory table
static bool change_refs_to_tmp_fields(THD *thd, Item **ref_pointer_array,
				      List<Item> &new_list1,
				      List<Item> &new_list2,
				      uint elements, List<Item> &items);
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static void init_tmptable_sum_functions(Item_sum **func);
static void update_tmptable_sum_func(Item_sum **func,TABLE *tmp_table);
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static void copy_sum_funcs(Item_sum **func_ptr, Item_sum **end);
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static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab);
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static bool init_sum_functions(Item_sum **func, Item_sum **end);
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static bool update_sum_func(Item_sum **func);
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static void select_describe(JOIN *join, bool need_tmp_table,bool need_order,
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			    bool distinct, const char *message=NullS);
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static Item *remove_additional_cond(Item* conds);
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/*
  This handles SELECT with and without UNION
*/

int handle_select(THD *thd, LEX *lex, select_result *result)
{
  int res;
  register SELECT_LEX *select_lex = &lex->select_lex;
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  DBUG_ENTER("handle_select");

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  if (select_lex->next_select() || select_lex->master_unit()->fake_select_lex)
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    res=mysql_union(thd, lex, result, &lex->unit);
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  else
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    res= mysql_select(thd, &select_lex->ref_pointer_array,
		      (TABLE_LIST*) select_lex->table_list.first,
		      select_lex->with_wild, select_lex->item_list,
		      select_lex->where,
		      select_lex->order_list.elements +
		      select_lex->group_list.elements,
		      (ORDER*) select_lex->order_list.first,
		      (ORDER*) select_lex->group_list.first,
		      select_lex->having,
		      (ORDER*) lex->proc_list.first,
		      select_lex->options | thd->options,
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		      result, &(lex->unit), &(lex->select_lex));
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  /* Don't set res if it's -1 as we may want this later */
  DBUG_PRINT("info",("res: %d  report_error: %d", res,
		     thd->net.report_error));
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  if (thd->net.report_error || res<0)
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  {
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    result->send_error(0, NullS);
    result->abort();
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    res= 1;					// Error sent to client
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  }
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  DBUG_RETURN(res);
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}

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/*
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  Function to setup clauses without sum functions
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*/
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inline int setup_without_group(THD *thd, Item **ref_pointer_array,
			       TABLE_LIST *tables,
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			       List<Item> &fields,
			       List<Item> &all_fields,
			       COND **conds,
			       ORDER *order,
			       ORDER *group, bool *hidden_group_fields)
{
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  bool save_allow_sum_func;
  int res;
  DBUG_ENTER("setup_without_group");

  save_allow_sum_func= thd->allow_sum_func;
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  thd->allow_sum_func= 0;
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  res= (setup_conds(thd, tables, conds) ||
        setup_order(thd, ref_pointer_array, tables, fields, all_fields,
                    order) ||
        setup_group(thd, ref_pointer_array, tables, fields, all_fields,
                    group, hidden_group_fields));
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  thd->allow_sum_func= save_allow_sum_func;
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  DBUG_RETURN(res);
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}

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/*****************************************************************************
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  Check fields, find best join, do the select and output fields.
  mysql_select assumes that all tables are already opened
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*****************************************************************************/

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/*
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  Prepare of whole select (including sub queries in future).
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  return -1 on error
          0 on success
*/
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int
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JOIN::prepare(Item ***rref_pointer_array,
	      TABLE_LIST *tables_init,
	      uint wild_num, COND *conds_init, uint og_num,
	      ORDER *order_init, ORDER *group_init,
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	      Item *having_init,
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	      ORDER *proc_param_init, SELECT_LEX *select_lex_arg,
	      SELECT_LEX_UNIT *unit_arg)
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{
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  DBUG_ENTER("JOIN::prepare");
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  // to prevent double initialization on EXPLAIN
  if (optimized)
    DBUG_RETURN(0);

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  conds= conds_init;
  order= order_init;
  group_list= group_init;
  having= having_init;
  proc_param= proc_param_init;
  tables_list= tables_init;
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  select_lex= select_lex_arg;
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  select_lex->join= this;
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  union_part= (unit_arg->first_select()->next_select() != 0);
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  /* Check that all tables, fields, conds and order are ok */

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  if (setup_tables(tables_list) ||
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      setup_wild(thd, tables_list, fields_list, &all_fields, wild_num) ||
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      select_lex->setup_ref_array(thd, og_num) ||
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      setup_fields(thd, (*rref_pointer_array), tables_list, fields_list, 1,
		   &all_fields, 1) ||
      setup_without_group(thd, (*rref_pointer_array), tables_list, fields_list,
			  all_fields, &conds, order, group_list, 
			  &hidden_group_fields))
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    DBUG_RETURN(-1);				/* purecov: inspected */

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  ref_pointer_array= *rref_pointer_array;
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  if (having)
  {
    thd->where="having clause";
    thd->allow_sum_func=1;
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    select_lex->having_fix_field= 1;
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    bool having_fix_rc= (!having->fixed &&
			 (having->fix_fields(thd, tables_list, &having) ||
			  having->check_cols(1)));
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    select_lex->having_fix_field= 0;
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    if (having_fix_rc || thd->net.report_error)
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      DBUG_RETURN(-1);				/* purecov: inspected */
    if (having->with_sum_func)
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      having->split_sum_func2(thd, ref_pointer_array, all_fields, &having);
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  }
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  // Is it subselect
  {
    Item_subselect *subselect;
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    if ((subselect= select_lex->master_unit()->item))
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    {
      Item_subselect::trans_res res;
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      if ((res= subselect->select_transformer(this)) !=
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	  Item_subselect::RES_OK)
	DBUG_RETURN((res == Item_subselect::RES_ERROR));
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    }
  }

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  if (setup_ftfuncs(select_lex)) /* should be after having->fix_fields */
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    DBUG_RETURN(-1);
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  /*
    Check if one one uses a not constant column with group functions
    and no GROUP BY.
    TODO:  Add check of calculation of GROUP functions and fields:
	   SELECT COUNT(*)+table.col1 from table1;
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  */
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  {
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    if (!group_list)
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    {
      uint flag=0;
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      List_iterator_fast<Item> it(fields_list);
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      Item *item;
      while ((item= it++))
      {
	if (item->with_sum_func)
	  flag|=1;
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	else if (!(flag & 2) && !item->const_during_execution())
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	  flag|=2;
      }
      if (flag == 3)
      {
	my_error(ER_MIX_OF_GROUP_FUNC_AND_FIELDS,MYF(0));
	DBUG_RETURN(-1);
      }
    }
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    TABLE_LIST *table_ptr;
    for (table_ptr= tables_list ; table_ptr ; table_ptr= table_ptr->next)
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      tables++;
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  }
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  {
    /* Caclulate the number of groups */
    send_group_parts= 0;
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    for (ORDER *group_tmp= group_list ; group_tmp ; group_tmp= group_tmp->next)
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      send_group_parts++;
  }
  
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  procedure= setup_procedure(thd, proc_param, result, fields_list, &error);
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  if (error)
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    goto err;					/* purecov: inspected */
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  if (procedure)
  {
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    if (setup_new_fields(thd, tables_list, fields_list, all_fields,
			 procedure->param_fields))
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	goto err;				/* purecov: inspected */
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    if (procedure->group)
    {
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      if (!test_if_subpart(procedure->group,group_list))
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      {						/* purecov: inspected */
	my_message(0,"Can't handle procedures with differents groups yet",
		   MYF(0));			/* purecov: inspected */
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	goto err;				/* purecov: inspected */
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      }
    }
#ifdef NOT_NEEDED
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    else if (!group_list && procedure->flags & PROC_GROUP)
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    {
      my_message(0,"Select must have a group with this procedure",MYF(0));
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      goto err;
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    }
#endif
    if (order && (procedure->flags & PROC_NO_SORT))
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    {						/* purecov: inspected */
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      my_message(0,"Can't use order with this procedure",MYF(0)); /* purecov: inspected */
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      goto err;					/* purecov: inspected */
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    }
  }

  /* Init join struct */
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  count_field_types(&tmp_table_param, all_fields, 0);
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  ref_pointer_array_size= all_fields.elements*sizeof(Item*);
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  this->group= group_list != 0;
  row_limit= ((select_distinct || order || group_list) ? HA_POS_ERROR :
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	      unit_arg->select_limit_cnt);
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  /* select_limit is used to decide if we are likely to scan the whole table */
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  select_limit= unit_arg->select_limit_cnt;
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  if (having || (select_options & OPTION_FOUND_ROWS))
    select_limit= HA_POS_ERROR;
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  do_send_rows = (unit_arg->select_limit_cnt) ? 1 : 0;
  unit= unit_arg;
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#ifdef RESTRICTED_GROUP
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  if (sum_func_count && !group_list && (func_count || field_count))
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  {
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    my_message(ER_WRONG_SUM_SELECT,ER(ER_WRONG_SUM_SELECT),MYF(0));
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    goto err;
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  }
#endif
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  /*
    We must not yet prepare the result table if it is the same as one of the 
    source tables (INSERT SELECT). This is checked in mysql_execute_command()
    and OPTION_BUFFER_RESULT is added to the select_options. A temporary 
    table is then used to hold the result. The preparation may disable 
    indexes on the result table, which may be used during the select, if it
    is the same table (Bug #6034). Do the preparation after the select phase.
  */
  if (! procedure && ! test(select_options & OPTION_BUFFER_RESULT) &&
      result && result->prepare(fields_list, unit_arg))
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    goto err;					/* purecov: inspected */

  if (select_lex->olap == ROLLUP_TYPE && rollup_init())
    goto err;
  if (alloc_func_list())
    goto err;

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  DBUG_RETURN(0); // All OK
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err:
  delete procedure;				/* purecov: inspected */
  procedure= 0;
  DBUG_RETURN(-1);				/* purecov: inspected */
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}
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/*
  test if it is known for optimisation IN subquery

  SYNOPSYS
    JOIN::test_in_subselect
    where - pointer for variable in which conditions should be
            stored if subquery is known

  RETURN
    1 - known
    0 - unknown
*/

bool JOIN::test_in_subselect(Item **where)
{
  if (conds->type() == Item::FUNC_ITEM &&
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      ((Item_func *)this->conds)->functype() == Item_func::EQ_FUNC &&
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      ((Item_func *)conds)->arguments()[0]->type() == Item::REF_ITEM &&
      ((Item_func *)conds)->arguments()[1]->type() == Item::FIELD_ITEM)
  {
    join_tab->info= "Using index";
    *where= 0;
    return 1;
  }
  if (conds->type() == Item::COND_ITEM &&
      ((class Item_func *)this->conds)->functype() ==
      Item_func::COND_AND_FUNC)
  {
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    if ((*where= remove_additional_cond(conds)))
      join_tab->info= "Using index; Using where";
    else
      join_tab->info= "Using index";
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    return 1;
  }
  return 0;
}


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/*
  global select optimisation.
  return 0 - success
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         1 - error
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  error code saved in field 'error'
*/
int
JOIN::optimize()
{
  DBUG_ENTER("JOIN::optimize");
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  // to prevent double initialization on EXPLAIN
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  if (optimized)
    DBUG_RETURN(0);
  optimized= 1;
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  // Ignore errors of execution if option IGNORE present
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  if (thd->lex->ignore)
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    thd->lex->current_select->no_error= 1;
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#ifdef HAVE_REF_TO_FIELDS			// Not done yet
  /* Add HAVING to WHERE if possible */
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  if (having && !group_list && !sum_func_count)
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  {
    if (!conds)
    {
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      conds= having;
      having= 0;
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    }
    else if ((conds=new Item_cond_and(conds,having)))
    {
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      conds->fix_fields(thd, tables_list, &conds);
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      conds->change_ref_to_fields(thd, tables_list);
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      conds->top_level_item();
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      having= 0;
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    }
  }
#endif

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  conds= optimize_cond(thd, conds, &cond_value);
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  if (thd->net.report_error)
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  {
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    error= 1;
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    DBUG_PRINT("error",("Error from optimize_cond"));
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    DBUG_RETURN(1);
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  }
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  {
    Item::cond_result having_value;
    having= optimize_cond(thd, having, &having_value);
    if (thd->net.report_error)
    {
      error= 1;
      DBUG_PRINT("error",("Error from optimize_cond"));
      DBUG_RETURN(1);
    }

    if (cond_value == Item::COND_FALSE || having_value == Item::COND_FALSE || 
       (!unit->select_limit_cnt && !(select_options & OPTION_FOUND_ROWS)))
    {						/* Impossible cond */
      zero_result_cause= having_value == Item::COND_FALSE ?
                           "Impossible HAVING" : "Impossible WHERE";
      error= 0;
      DBUG_RETURN(0);
    }
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  }

  /* Optimize count(*), min() and max() */
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  if (tables_list && tmp_table_param.sum_func_count && ! group_list)
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  {
    int res;
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    /*
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      opt_sum_query() returns -1 if no rows match to the WHERE conditions,
      or 1 if all items were resolved, or 0, or an error number HA_ERR_...
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    */
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    if ((res=opt_sum_query(tables_list, all_fields, conds)))
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    {
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      if (res > 1)
      {
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	DBUG_RETURN(1);
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      }
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      if (res < 0)
      {
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	zero_result_cause= "No matching min/max row";
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	error=0;
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	DBUG_RETURN(0);
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      }
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      zero_result_cause= "Select tables optimized away";
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      tables_list= 0;				// All tables resolved
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      /*
        Extract all table-independent conditions and replace the WHERE
        clause with them. All other conditions were computed by opt_sum_query
        and the MIN/MAX/COUNT function(s) have been replaced by constants,
        so there is no need to compute the whole WHERE clause again.
        Notice that make_cond_for_table() will always succeed to remove all
        computed conditions, because opt_sum_query() is applicable only to
        conjunctions.
      */
      if (conds)
      {
        COND *table_independent_conds=
          make_cond_for_table(conds, PSEUDO_TABLE_BITS, 0);
        DBUG_EXECUTE("where",
                     print_where(table_independent_conds,
                                 "where after opt_sum_query()"););
        conds= table_independent_conds;
      }
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    }
  }
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  if (!tables_list)
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  {
    error= 0;
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    DBUG_RETURN(0);
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  }
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  error= -1;					// Error is sent to client
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  sort_by_table= get_sort_by_table(order, group_list, tables_list);
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  /* Calculate how to do the join */
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  thd->proc_info= "statistics";
  if (make_join_statistics(this, tables_list, conds, &keyuse) ||
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      thd->is_fatal_error)
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  {
    DBUG_PRINT("error",("Error: make_join_statistics() failed"));
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    DBUG_RETURN(1);
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  }
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  /* Remove distinct if only const tables */
  select_distinct= select_distinct && (const_tables != tables);
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  thd->proc_info= "preparing";
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  if (result->initialize_tables(this))
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  {
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    DBUG_PRINT("error",("Error: initialize_tables() failed"));
    DBUG_RETURN(1);				// error == -1
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  }
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  if (const_table_map != found_const_table_map &&
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      !(select_options & SELECT_DESCRIBE) &&
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      (!conds ||
       !(conds->used_tables() & RAND_TABLE_BIT) ||
       select_lex->master_unit() == &thd->lex->unit)) // upper level SELECT
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  {
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    zero_result_cause= "no matching row in const table";
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    DBUG_PRINT("error",("Error: %s", zero_result_cause));
    error= 0;
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    DBUG_RETURN(0);
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  }
  if (!(thd->options & OPTION_BIG_SELECTS) &&
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      best_read > (double) thd->variables.max_join_size &&
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      !(select_options & SELECT_DESCRIBE))
  {						/* purecov: inspected */
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    my_message(ER_TOO_BIG_SELECT, ER(ER_TOO_BIG_SELECT), MYF(0));
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    error= -1;
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    DBUG_RETURN(1);
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  }
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  if (const_tables && !thd->locked_tables &&
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      !(select_options & SELECT_NO_UNLOCK))
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    mysql_unlock_some_tables(thd, table, const_tables);
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  if (!conds && outer_join)
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  {
    /* Handle the case where we have an OUTER JOIN without a WHERE */
    conds=new Item_int((longlong) 1,1);	// Always true
  }
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  select=make_select(*table, const_table_map,
		     const_table_map, conds, &error);
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  if (error)
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  {						/* purecov: inspected */
    error= -1;					/* purecov: inspected */
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    DBUG_PRINT("error",("Error: make_select() failed"));
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    DBUG_RETURN(1);
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  }
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  if (make_join_select(this, select, conds))
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  {
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    zero_result_cause=
      "Impossible WHERE noticed after reading const tables";
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    DBUG_RETURN(0);				// error == 0
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  }

  error= -1;					/* if goto err */

  /* Optimize distinct away if possible */
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  {
    ORDER *org_order= order;
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    order=remove_const(this, order,conds,1, &simple_order);
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    /*
      If we are using ORDER BY NULL or ORDER BY const_expression,
      return result in any order (even if we are using a GROUP BY)
    */
    if (!order && org_order)
      skip_sort_order= 1;
  }
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  /*
     Check if we can optimize away GROUP BY/DISTINCT.
     We can do that if there are no aggregate functions and the
     fields in DISTINCT clause (if present) and/or columns in GROUP BY
     (if present) contain direct references to all key parts of
     an unique index (in whatever order).
     Note that the unique keys for DISTINCT and GROUP BY should not
     be the same (as long as they are unique).

     The FROM clause must contain a single non-constant table.
  */
  if (tables - const_tables == 1 && (group_list || select_distinct) &&
      !tmp_table_param.sum_func_count)
  {
    if (group_list &&
       list_contains_unique_index(join_tab[const_tables].table,
                                 find_field_in_order_list,
                                 (void *) group_list))
    {
      group_list= 0;
      group= 0;
    }
    if (select_distinct &&
       list_contains_unique_index(join_tab[const_tables].table,
                                 find_field_in_item_list,
                                 (void *) &fields_list))
    {
      select_distinct= 0;
    }
  }
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  if (group_list || tmp_table_param.sum_func_count)
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  {
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    if (! hidden_group_fields && rollup.state == ROLLUP::STATE_NONE)
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      select_distinct=0;
  }
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  else if (select_distinct && tables - const_tables == 1)
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  {
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    /*
      We are only using one table. In this case we change DISTINCT to a
      GROUP BY query if:
      - The GROUP BY can be done through indexes (no sort) and the ORDER
        BY only uses selected fields.
	(In this case we can later optimize away GROUP BY and ORDER BY)
      - We are scanning the whole table without LIMIT
        This can happen if:
        - We are using CALC_FOUND_ROWS
        - We are using an ORDER BY that can't be optimized away.

      We don't want to use this optimization when we are using LIMIT
      because in this case we can just create a temporary table that
      holds LIMIT rows and stop when this table is full.
    */
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    JOIN_TAB *tab= &join_tab[const_tables];
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    bool all_order_fields_used;
    if (order)
      skip_sort_order= test_if_skip_sort_order(tab, order, select_limit, 1);
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    if ((group_list=create_distinct_group(thd, select_lex->ref_pointer_array,
                                          order, fields_list,
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				          &all_order_fields_used)))
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    {
      bool skip_group= (skip_sort_order &&
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			test_if_skip_sort_order(tab, group_list, select_limit,
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						1) != 0);
      if ((skip_group && all_order_fields_used) ||
	  select_limit == HA_POS_ERROR ||
	  (order && !skip_sort_order))
      {
	/*  Change DISTINCT to GROUP BY */
	select_distinct= 0;
	no_order= !order;
	if (all_order_fields_used)
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	{
	  if (order && skip_sort_order)
	  {
	    /*
	      Force MySQL to read the table in sorted order to get result in
	      ORDER BY order.
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	    */
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	    tmp_table_param.quick_group=0;
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	  }
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	  order=0;
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        }
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	group=1;				// For end_write_group
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      }
      else
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	group_list= 0;
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    }
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    else if (thd->is_fatal_error)			// End of memory
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      DBUG_RETURN(1);
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  }
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  simple_group= 0;
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  {
    ORDER *old_group_list;
    group_list= remove_const(this, (old_group_list= group_list), conds,
                             rollup.state == ROLLUP::STATE_NONE,
			     &simple_group);
    if (old_group_list && !group_list)
      select_distinct= 0;
  }
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  if (!group_list && group)
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  {
    order=0;					// The output has only one row
    simple_order=1;
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    select_distinct= 0;                       // No need in distinct for 1 row
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  }

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  calc_group_buffer(this, group_list);
  send_group_parts= tmp_table_param.group_parts; /* Save org parts */
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  if (procedure && procedure->group)
  {
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    group_list= procedure->group= remove_const(this, procedure->group, conds,
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					       1, &simple_group);
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    calc_group_buffer(this, group_list);
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  }

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  if (test_if_subpart(group_list, order) ||
      (!group_list && tmp_table_param.sum_func_count))
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    order=0;

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  // Can't use sort on head table if using row cache
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  if (full_join)
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  {
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    if (group_list)
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      simple_group=0;
    if (order)
      simple_order=0;
  }

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  /*
    Check if we need to create a temporary table.
    This has to be done if all tables are not already read (const tables)
    and one of the following conditions holds:
    - We are using DISTINCT (simple distinct's are already optimized away)
    - We are using an ORDER BY or GROUP BY on fields not in the first table
    - We are using different ORDER BY and GROUP BY orders
    - The user wants us to buffer the result.
  */
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  need_tmp= (const_tables != tables &&
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	     ((select_distinct || !simple_order || !simple_group) ||
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	      (group_list && order) ||
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	      test(select_options & OPTION_BUFFER_RESULT)));
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  // No cache for MATCH
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  make_join_readinfo(this,
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		     (select_options & (SELECT_DESCRIBE |
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					SELECT_NO_JOIN_CACHE)) |
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		     (select_lex->ftfunc_list->elements ?
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		      SELECT_NO_JOIN_CACHE : 0));
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  /* Perform FULLTEXT search before all regular searches */
  if (!(select_options & SELECT_DESCRIBE))
    init_ftfuncs(thd, select_lex, test(order));

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  /*
    is this simple IN subquery?
  */
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  if (!group_list && !order &&
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      unit->item && unit->item->substype() == Item_subselect::IN_SUBS &&
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      tables == 1 && conds &&
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      !unit->first_select()->next_select())
  {
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    if (!having)
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    {
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      Item *where= 0;
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      if (join_tab[0].type == JT_EQ_REF &&
	  join_tab[0].ref.items[0]->name == in_left_expr_name)
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      {
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	if (test_in_subselect(&where))
	{
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	  join_tab[0].type= JT_UNIQUE_SUBQUERY;
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	  error= 0;
	  DBUG_RETURN(unit->item->
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		      change_engine(new
				    subselect_uniquesubquery_engine(thd,
								    join_tab,
								    unit->item,
								    where)));
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	}
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      }
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      else if (join_tab[0].type == JT_REF &&
	       join_tab[0].ref.items[0]->name == in_left_expr_name)
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      {
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	if (test_in_subselect(&where))
	{
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	  join_tab[0].type= JT_INDEX_SUBQUERY;
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	  error= 0;
	  DBUG_RETURN(unit->item->
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		      change_engine(new
				    subselect_indexsubquery_engine(thd,
								   join_tab,
								   unit->item,
								   where,
								   0)));
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	}
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      }
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    } else if (join_tab[0].type == JT_REF_OR_NULL &&
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	       join_tab[0].ref.items[0]->name == in_left_expr_name &&
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	       having->type() == Item::FUNC_ITEM &&
	       ((Item_func *) having)->functype() ==
	       Item_func::ISNOTNULLTEST_FUNC)
    {
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      join_tab[0].type= JT_INDEX_SUBQUERY;
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      error= 0;
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      if ((conds= remove_additional_cond(conds)))
	join_tab->info= "Using index; Using where";
      else
	join_tab->info= "Using index";
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      DBUG_RETURN(unit->item->
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		  change_engine(new subselect_indexsubquery_engine(thd,
								   join_tab,
								   unit->item,
								   conds,
								   1)));
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    }
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  }
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  /*
    Need to tell Innobase that to play it safe, it should fetch all
    columns of the tables: this is because MySQL may build row
    pointers for the rows, and for all columns of the primary key the
    field->query_id has not necessarily been set to thd->query_id by
    MySQL.
  */
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#ifdef HAVE_INNOBASE_DB
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  if (need_tmp || select_distinct || group_list || order)
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  {
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    for (uint i_h = const_tables; i_h < tables; i_h++)
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    {
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      TABLE* table_h = join_tab[i_h].table;
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      table_h->file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY);
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    }
  }
#endif

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  DBUG_EXECUTE("info",TEST_join(this););
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  /*
    Because filesort always does a full table scan or a quick range scan
    we must add the removed reference to the select for the table.
    We only need to do this when we have a simple_order or simple_group
    as in other cases the join is done before the sort.
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  */
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  if (const_tables != tables &&
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      (order || group_list) &&
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      join_tab[const_tables].type != JT_ALL &&
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      join_tab[const_tables].type != JT_FT &&
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      join_tab[const_tables].type != JT_REF_OR_NULL &&
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      (order && simple_order || group_list && simple_group))
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  {
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    if (add_ref_to_table_cond(thd,&join_tab[const_tables]))
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      DBUG_RETURN(1);
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  }

  if (!(select_options & SELECT_BIG_RESULT) &&
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      ((group_list && const_tables != tables &&
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	(!simple_group ||
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	 !test_if_skip_sort_order(&join_tab[const_tables], group_list,
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				  unit->select_limit_cnt, 0))) ||
       select_distinct) &&
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      tmp_table_param.quick_group && !procedure)
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  {
    need_tmp=1; simple_order=simple_group=0;	// Force tmp table without sort
  }
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  tmp_having= having;
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  if (select_options & SELECT_DESCRIBE)
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  {
    error= 0;
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    DBUG_RETURN(0);
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  }
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  having= 0;

  /* Create a tmp table if distinct or if the sort is too complicated */
  if (need_tmp)
  {
    DBUG_PRINT("info",("Creating tmp table"));
    thd->proc_info="Creating tmp table";

    init_items_ref_array();
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    tmp_table_param.hidden_field_count= (all_fields.elements -
					 fields_list.elements);
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    ORDER *tmp_group= ((!simple_group && !procedure &&
                        !(test_flags & TEST_NO_KEY_GROUP)) ? group_list :
                                                             (ORDER*) 0);
    /*
      Pushing LIMIT to the temporary table creation is not applicable
      when there is ORDER BY or GROUP BY or there is no GROUP BY, but
      there are aggregate functions, because in all these cases we need
      all result rows.
    */
    ha_rows tmp_rows_limit= ((order == 0 || skip_sort_order ||
                              test(select_options & OPTION_BUFFER_RESULT)) &&
                             !tmp_group &&
                             !thd->lex->current_select->with_sum_func) ?
                            select_limit : HA_POS_ERROR;

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    if (!(exec_tmp_table1 =
	  create_tmp_table(thd, &tmp_table_param, all_fields,
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                           tmp_group,
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			   group_list ? 0 : select_distinct,
			   group_list && simple_group,
			   select_options,
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                           tmp_rows_limit,
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			   (char *) "")))
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      DBUG_RETURN(1);
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    /*
      We don't have to store rows in temp table that doesn't match HAVING if:
      - we are sorting the table and writing complete group rows to the
        temp table.
      - We are using DISTINCT without resolving the distinct as a GROUP BY
        on all columns.
      
      If having is not handled here, it will be checked before the row
      is sent to the client.
    */    
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    if (tmp_having && 
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	(sort_and_group || (exec_tmp_table1->distinct && !group_list)))
      having= tmp_having;

    /* if group or order on first table, sort first */
    if (group_list && simple_group)
    {
      DBUG_PRINT("info",("Sorting for group"));
      thd->proc_info="Sorting for group";
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      if (create_sort_index(thd, this, group_list,
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			    HA_POS_ERROR, HA_POS_ERROR) ||
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	  alloc_group_fields(this, group_list) ||
	  make_sum_func_list(all_fields, fields_list, 1))
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	DBUG_RETURN(1);
      group_list=0;
    }
    else
    {
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      if (make_sum_func_list(all_fields, fields_list, 0))
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	DBUG_RETURN(1);
      if (!group_list && ! exec_tmp_table1->distinct && order && simple_order)
      {
	DBUG_PRINT("info",("Sorting for order"));
	thd->proc_info="Sorting for order";
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	if (create_sort_index(thd, this, order,
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                              HA_POS_ERROR, HA_POS_ERROR))
	  DBUG_RETURN(1);
	order=0;
      }
    }
    
    /*
      Optimize distinct when used on some of the tables
      SELECT DISTINCT t1.a FROM t1,t2 WHERE t1.b=t2.b
      In this case we can stop scanning t2 when we have found one t1.a
    */

    if (exec_tmp_table1->distinct)
    {
      table_map used_tables= thd->used_tables;
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      JOIN_TAB *last_join_tab= join_tab+tables-1;
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      do
      {
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	if (used_tables & last_join_tab->table->map)
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	  break;
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	last_join_tab->not_used_in_distinct=1;
      } while (last_join_tab-- != join_tab);
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      /* Optimize "select distinct b from t1 order by key_part_1 limit #" */
      if (order && skip_sort_order)
      {
 	/* Should always succeed */
1021
	if (test_if_skip_sort_order(&join_tab[const_tables],
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				    order, unit->select_limit_cnt, 0))
	  order=0;
      }
    }
    
1027
    if (thd->lex->subqueries)
1028 1029 1030
    {
      if (!(tmp_join= (JOIN*)thd->alloc(sizeof(JOIN))))
	DBUG_RETURN(-1);
1031
      error= 0;				// Ensure that tmp_join.error= 0
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      restore_tmp();
    }
  }

1036
  error= 0;
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  DBUG_RETURN(0);
}

1040

1041
/*
1042
  Restore values in temporary join
1043
*/
1044
void JOIN::restore_tmp()
1045
{
1046
  memcpy(tmp_join, this, (size_t) sizeof(JOIN));
1047 1048
}

1049

1050 1051 1052 1053
int
JOIN::reinit()
{
  DBUG_ENTER("JOIN::reinit");
1054
  /* TODO move to unit reinit */
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  unit->offset_limit_cnt =select_lex->offset_limit;
  unit->select_limit_cnt =select_lex->select_limit+select_lex->offset_limit;
  if (unit->select_limit_cnt < select_lex->select_limit)
    unit->select_limit_cnt= HA_POS_ERROR;		// no limit
  if (unit->select_limit_cnt == HA_POS_ERROR)
    select_lex->options&= ~OPTION_FOUND_ROWS;
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  if (!optimized && setup_tables(tables_list))
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    DBUG_RETURN(1);
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1065
  /* Reset of sum functions */
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  first_record= 0;
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  if (exec_tmp_table1)
  {
    exec_tmp_table1->file->extra(HA_EXTRA_RESET_STATE);
    exec_tmp_table1->file->delete_all_rows();
    free_io_cache(exec_tmp_table1);
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    filesort_free_buffers(exec_tmp_table1);
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  }
  if (exec_tmp_table2)
  {
    exec_tmp_table2->file->extra(HA_EXTRA_RESET_STATE);
    exec_tmp_table2->file->delete_all_rows();
    free_io_cache(exec_tmp_table2);
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    filesort_free_buffers(exec_tmp_table2);
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  }
  if (items0)
1083
    set_items_ref_array(items0);
1084

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  if (join_tab_save)
    memcpy(join_tab, join_tab_save, sizeof(JOIN_TAB) * tables);

1088 1089 1090
  if (tmp_join)
    restore_tmp();

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  if (sum_funcs)
  {
    Item_sum *func, **func_ptr= sum_funcs;
    while ((func= *(func_ptr++)))
      func->clear();
  }

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  DBUG_RETURN(0);
}

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bool
JOIN::save_join_tab()
{
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  if (!join_tab_save && select_lex->master_unit()->uncacheable)
1106
  {
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    if (!(join_tab_save= (JOIN_TAB*)thd->memdup((gptr) join_tab,
						sizeof(JOIN_TAB) * tables)))
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      return 1;
  }
  return 0;
}


1115
/*
1116
  Exec select
1117 1118 1119 1120
*/
void
JOIN::exec()
{
1121
  List<Item> *columns_list= &fields_list;
1122 1123
  int      tmp_error;
  DBUG_ENTER("JOIN::exec");
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1125
  error= 0;
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  if (procedure)
  {
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    procedure_fields_list= fields_list;
    if (procedure->change_columns(procedure_fields_list) ||
	result->prepare(procedure_fields_list, unit))
1131 1132
    {
      thd->limit_found_rows= thd->examined_row_count= 0;
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      DBUG_VOID_RETURN;
1134
    }
1135
    columns_list= &procedure_fields_list;
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  }
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  else if (test(select_options & OPTION_BUFFER_RESULT) &&
           result && result->prepare(fields_list, unit))
  {
    error= 1;
    thd->limit_found_rows= thd->examined_row_count= 0;
    DBUG_VOID_RETURN;
  }
1144

1145
  if (!tables_list && (tables || !select_lex->with_sum_func))
1146 1147
  {                                           // Only test of functions
    if (select_options & SELECT_DESCRIBE)
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      select_describe(this, FALSE, FALSE, FALSE,
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		      (zero_result_cause?zero_result_cause:"No tables used"));
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    else
    {
1152
      result->send_fields(*columns_list, 1);
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      /*
        We have to test for 'conds' here as the WHERE may not be constant
        even if we don't have any tables for prepared statements or if
        conds uses something like 'rand()'.
      */
      if (cond_value != Item::COND_FALSE &&
          (!conds || conds->val_int()) &&
          (!having || having->val_int()))
1161
      {
1162 1163 1164
	if (do_send_rows &&
            (procedure ? (procedure->send_row(procedure_fields_list) ||
             procedure->end_of_records()) : result->send_data(fields_list)))
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	  error= 1;
1166
	else
1167
	{
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	  error= (int) result->send_eof();
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	  send_records= ((select_options & OPTION_FOUND_ROWS) ? 1 :
                         thd->sent_row_count);
1171
	}
1172 1173
      }
      else
1174
      {
1175
	error=(int) result->send_eof();
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        send_records= 0;
      }
1178
    }
1179 1180
    /* Single select (without union) always returns 0 or 1 row */
    thd->limit_found_rows= send_records;
1181
    thd->examined_row_count= 0;
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    DBUG_VOID_RETURN;
  }
1184 1185 1186 1187 1188 1189
  /* 
    don't reset the found rows count if there're no tables
    as FOUND_ROWS() may be called.
  */  
  if (tables)
    thd->limit_found_rows= thd->examined_row_count= 0;
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  if (zero_result_cause)
  {
1193
    (void) return_zero_rows(this, result, tables_list, *columns_list,
1194
			    send_row_on_empty_set(),
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			    select_options,
			    zero_result_cause,
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			    having, procedure,
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			    unit);
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    DBUG_VOID_RETURN;
  }

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  if (select_options & SELECT_DESCRIBE)
  {
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    /*
      Check if we managed to optimize ORDER BY away and don't use temporary
      table to resolve ORDER BY: in that case, we only may need to do
      filesort for GROUP BY.
    */
    if (!order && !no_order && (!skip_sort_order || !need_tmp))
    {
      /*
	Reset 'order' to 'group_list' and reinit variables describing
	'order'
      */
      order= group_list;
      simple_order= simple_group;
      skip_sort_order= 0;
    }
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    if (order &&
1220
	(const_tables == tables ||
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 	 ((simple_order || skip_sort_order) &&
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	  test_if_skip_sort_order(&join_tab[const_tables], order,
1223
				  select_limit, 0))))
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      order=0;
1225
    having= tmp_having;
1226
    select_describe(this, need_tmp,
1227
		    order != 0 && !skip_sort_order,
1228 1229
		    select_distinct,
                    !tables ? "No tables used" : NullS);
1230
    DBUG_VOID_RETURN;
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  }

1233 1234 1235 1236
  JOIN *curr_join= this;
  List<Item> *curr_all_fields= &all_fields;
  List<Item> *curr_fields_list= &fields_list;
  TABLE *curr_tmp_table= 0;
1237

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  /* Create a tmp table if distinct or if the sort is too complicated */
  if (need_tmp)
  {
1241 1242 1243
    if (tmp_join)
      curr_join= tmp_join;
    curr_tmp_table= exec_tmp_table1;
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1244 1245

    /* Copy data to the temporary table */
1246
    thd->proc_info= "Copying to tmp table";
1247 1248
    
    if ((tmp_error= do_select(curr_join, (List<Item> *) 0, curr_tmp_table, 0)))
1249
    {
1250 1251
      error= tmp_error;
      DBUG_VOID_RETURN;
1252
    }
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    curr_tmp_table->file->info(HA_STATUS_VARIABLE);
    
    if (curr_join->having)
      curr_join->having= curr_join->tmp_having= 0; // Allready done
    
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    /* Change sum_fields reference to calculated fields in tmp_table */
1259 1260
    curr_join->all_fields= *curr_all_fields;
    if (!items1)
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    {
1262 1263 1264
      items1= items0 + all_fields.elements;
      if (sort_and_group || curr_tmp_table->group)
      {
1265
	if (change_to_use_tmp_fields(thd, items1,
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				     tmp_fields_list1, tmp_all_fields1,
				     fields_list.elements, all_fields))
	  DBUG_VOID_RETURN;
      }
      else
      {
	if (change_refs_to_tmp_fields(thd, items1,
				      tmp_fields_list1, tmp_all_fields1,
				      fields_list.elements, all_fields))
	  DBUG_VOID_RETURN;
      }
      curr_join->tmp_all_fields1= tmp_all_fields1;
      curr_join->tmp_fields_list1= tmp_fields_list1;
      curr_join->items1= items1;
    }
    curr_all_fields= &tmp_all_fields1;
    curr_fields_list= &tmp_fields_list1;
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    curr_join->set_items_ref_array(items1);
1284 1285 1286 1287 1288 1289 1290 1291
    
    if (sort_and_group || curr_tmp_table->group)
    {
      curr_join->tmp_table_param.field_count+= 
	curr_join->tmp_table_param.sum_func_count+
	curr_join->tmp_table_param.func_count;
      curr_join->tmp_table_param.sum_func_count= 
	curr_join->tmp_table_param.func_count= 0;
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    }
    else
    {
1295 1296 1297
      curr_join->tmp_table_param.field_count+= 
	curr_join->tmp_table_param.func_count;
      curr_join->tmp_table_param.func_count= 0;
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    }
1299 1300
    
    // procedure can't be used inside subselect => we do nothing special for it
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    if (procedure)
      procedure->update_refs();
1303 1304
    
    if (curr_tmp_table->group)
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    {						// Already grouped
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      if (!curr_join->order && !curr_join->no_order && !skip_sort_order)
1307 1308
	curr_join->order= curr_join->group_list;  /* order by group */
      curr_join->group_list= 0;
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    }
1310
    
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    /*
1312 1313 1314 1315 1316
      If we have different sort & group then we must sort the data by group
      and copy it to another tmp table
      This code is also used if we are using distinct something
      we haven't been able to store in the temporary table yet
      like SEC_TO_TIME(SUM(...)).
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    */

1319 1320 1321 1322 1323
    if (curr_join->group_list && (!test_if_subpart(curr_join->group_list,
						   curr_join->order) || 
				  curr_join->select_distinct) ||
	(curr_join->select_distinct &&
	 curr_join->tmp_table_param.using_indirect_summary_function))
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    {					/* Must copy to another table */
      DBUG_PRINT("info",("Creating group table"));
1326
      
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      /* Free first data from old join */
1328
      curr_join->join_free(0);
1329
      if (make_simple_join(curr_join, curr_tmp_table))
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	DBUG_VOID_RETURN;
1331
      calc_group_buffer(curr_join, group_list);
1332 1333
      count_field_types(&curr_join->tmp_table_param,
			curr_join->tmp_all_fields1,
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			curr_join->select_distinct && !curr_join->group_list);
      curr_join->tmp_table_param.hidden_field_count= 
	(curr_join->tmp_all_fields1.elements-
	 curr_join->tmp_fields_list1.elements);
      
      
      if (exec_tmp_table2)
	curr_tmp_table= exec_tmp_table2;
      else
      {
	/* group data to new table */
	if (!(curr_tmp_table=
	      exec_tmp_table2= create_tmp_table(thd,
						&curr_join->tmp_table_param,
						*curr_all_fields,
						(ORDER*) 0,
						curr_join->select_distinct && 
						!curr_join->group_list,
						1, curr_join->select_options,
1353 1354
						HA_POS_ERROR,
						(char *) "")))
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	  DBUG_VOID_RETURN;
	curr_join->exec_tmp_table2= exec_tmp_table2;
      }
1358
      if (curr_join->group_list)
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      {
1360
	thd->proc_info= "Creating sort index";
1361 1362 1363 1364
	if (curr_join->join_tab == join_tab && save_join_tab())
	{
	  DBUG_VOID_RETURN;
	}
1365
	if (create_sort_index(thd, curr_join, curr_join->group_list,
1366
			      HA_POS_ERROR, HA_POS_ERROR) ||
1367
	    make_group_fields(this, curr_join))
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	{
1369
	  DBUG_VOID_RETURN;
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	}
      }
1372
      
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      thd->proc_info="Copying to group table";
1374
      tmp_error= -1;
1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388
      if (curr_join != this)
      {
	if (sum_funcs2)
	{
	  curr_join->sum_funcs= sum_funcs2;
	  curr_join->sum_funcs_end= sum_funcs_end2; 
	}
	else
	{
	  curr_join->alloc_func_list();
	  sum_funcs2= curr_join->sum_funcs;
	  sum_funcs_end2= curr_join->sum_funcs_end;
	}
      }
1389
      if (curr_join->make_sum_func_list(*curr_all_fields, *curr_fields_list,
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					1))
        DBUG_VOID_RETURN;
      curr_join->group_list= 0;
      if ((tmp_error= do_select(curr_join, (List<Item> *) 0, curr_tmp_table,
1394
				0)))
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      {
1396
	error= tmp_error;
1397
	DBUG_VOID_RETURN;
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      }
1399 1400 1401 1402 1403 1404 1405 1406
      end_read_record(&curr_join->join_tab->read_record);
      curr_join->const_tables= curr_join->tables; // Mark free for join_free()
      curr_join->join_tab[0].table= 0;           // Table is freed
      
      // No sum funcs anymore
      if (!items2)
      {
	items2= items1 + all_fields.elements;
1407
	if (change_to_use_tmp_fields(thd, items2,
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				     tmp_fields_list2, tmp_all_fields2, 
				     fields_list.elements, tmp_all_fields1))
	  DBUG_VOID_RETURN;
	curr_join->tmp_fields_list2= tmp_fields_list2;
	curr_join->tmp_all_fields2= tmp_all_fields2;
      }
      curr_fields_list= &curr_join->tmp_fields_list2;
      curr_all_fields= &curr_join->tmp_all_fields2;
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      curr_join->set_items_ref_array(items2);
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      curr_join->tmp_table_param.field_count+= 
	curr_join->tmp_table_param.sum_func_count;
      curr_join->tmp_table_param.sum_func_count= 0;
    }
    if (curr_tmp_table->distinct)
      curr_join->select_distinct=0;		/* Each row is unique */
    
1424
    curr_join->join_free(0);			/* Free quick selects */
1425
    if (curr_join->select_distinct && ! curr_join->group_list)
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    {
      thd->proc_info="Removing duplicates";
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      if (curr_join->tmp_having)
	curr_join->tmp_having->update_used_tables();
      if (remove_duplicates(curr_join, curr_tmp_table,
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			    *curr_fields_list, curr_join->tmp_having))
1432
	DBUG_VOID_RETURN;
1433 1434
      curr_join->tmp_having=0;
      curr_join->select_distinct=0;
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    }
1436 1437
    curr_tmp_table->reginfo.lock_type= TL_UNLOCK;
    if (make_simple_join(curr_join, curr_tmp_table))
1438
      DBUG_VOID_RETURN;
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    calc_group_buffer(curr_join, curr_join->group_list);
    count_field_types(&curr_join->tmp_table_param, *curr_all_fields, 0);
    
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  }
  if (procedure)
1444 1445 1446
    count_field_types(&curr_join->tmp_table_param, *curr_all_fields, 0);
  
  if (curr_join->group || curr_join->tmp_table_param.sum_func_count ||
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      (procedure && (procedure->flags & PROC_GROUP)))
  {
1449 1450 1451 1452
    if (make_group_fields(this, curr_join))
    {
      DBUG_VOID_RETURN;
    }
1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476
    if (!items3)
    {
      if (!items0)
	init_items_ref_array();
      items3= ref_pointer_array + (all_fields.elements*4);
      setup_copy_fields(thd, &curr_join->tmp_table_param,
			items3, tmp_fields_list3, tmp_all_fields3,
			curr_fields_list->elements, *curr_all_fields);
      tmp_table_param.save_copy_funcs= curr_join->tmp_table_param.copy_funcs;
      tmp_table_param.save_copy_field= curr_join->tmp_table_param.copy_field;
      tmp_table_param.save_copy_field_end=
	curr_join->tmp_table_param.copy_field_end;
      curr_join->tmp_all_fields3= tmp_all_fields3;
      curr_join->tmp_fields_list3= tmp_fields_list3;
    }
    else
    {
      curr_join->tmp_table_param.copy_funcs= tmp_table_param.save_copy_funcs;
      curr_join->tmp_table_param.copy_field= tmp_table_param.save_copy_field;
      curr_join->tmp_table_param.copy_field_end=
	tmp_table_param.save_copy_field_end;
    }
    curr_fields_list= &tmp_fields_list3;
    curr_all_fields= &tmp_all_fields3;
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    curr_join->set_items_ref_array(items3);
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1479 1480
    if (curr_join->make_sum_func_list(*curr_all_fields, *curr_fields_list,
				      1) || thd->is_fatal_error)
1481
      DBUG_VOID_RETURN;
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  }
1483
  if (curr_join->group_list || curr_join->order)
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  {
    DBUG_PRINT("info",("Sorting for send_fields"));
    thd->proc_info="Sorting result";
    /* If we have already done the group, add HAVING to sorted table */
1488 1489
    if (curr_join->tmp_having && ! curr_join->group_list && 
	! curr_join->sort_and_group)
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    {
1491 1492
      // Some tables may have been const
      curr_join->tmp_having->update_used_tables();
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      JOIN_TAB *curr_table= &curr_join->join_tab[curr_join->const_tables];
      table_map used_tables= (curr_join->const_table_map |
			      curr_table->table->map);
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      Item* sort_table_cond= make_cond_for_table(curr_join->tmp_having,
						 used_tables,
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						 used_tables);
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      if (sort_table_cond)
      {
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	if (!curr_table->select)
	  if (!(curr_table->select= new SQL_SELECT))
1504
	    DBUG_VOID_RETURN;
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	if (!curr_table->select->cond)
	  curr_table->select->cond= sort_table_cond;
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	else					// This should never happen
1508
	{
1509
	  if (!(curr_table->select->cond=
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		new Item_cond_and(curr_table->select->cond,
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				  sort_table_cond)))
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	    DBUG_VOID_RETURN;
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	  /*
	    Item_cond_and do not need fix_fields for execution, its parameters
	    are fixed or do not need fix_fields, too
	  */
	  curr_table->select->cond->quick_fix_field();
1518
	}
1519
	curr_table->select_cond= curr_table->select->cond;
1520 1521
	curr_table->select_cond->top_level_item();
	DBUG_EXECUTE("where",print_where(curr_table->select->cond,
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					 "select and having"););
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	curr_join->tmp_having= make_cond_for_table(curr_join->tmp_having,
						   ~ (table_map) 0,
						   ~used_tables);
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	DBUG_EXECUTE("where",print_where(curr_join->tmp_having,
                                         "having after sort"););
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      }
    }
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    {
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      if (group)
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	curr_join->select_limit= HA_POS_ERROR;
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      else
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      {
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	/*
	  We can abort sorting after thd->select_limit rows if we there is no
	  WHERE clause for any tables after the sorted one.
	*/
1539
	JOIN_TAB *curr_table= &curr_join->join_tab[curr_join->const_tables+1];
1540
	JOIN_TAB *end_table= &curr_join->join_tab[curr_join->tables];
1541
	for (; curr_table < end_table ; curr_table++)
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	{
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	  /*
	    table->keyuse is set in the case there was an original WHERE clause
	    on the table that was optimized away.
	    table->on_expr tells us that it was a LEFT JOIN and there will be
	    at least one row generated from the table.
	  */
1549 1550
	  if (curr_table->select_cond ||
	      (curr_table->keyuse && !curr_table->on_expr))
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	  {
	    /* We have to sort all rows */
1553
	    curr_join->select_limit= HA_POS_ERROR;
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	    break;
	  }
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	}
      }
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      if (curr_join->join_tab == join_tab && save_join_tab())
      {
	DBUG_VOID_RETURN;
      }
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      /*
	Here we sort rows for ORDER BY/GROUP BY clause, if the optimiser
	chose FILESORT to be faster than INDEX SCAN or there is no 
	suitable index present.
	Note, that create_sort_index calls test_if_skip_sort_order and may
	finally replace sorting with index scan if there is a LIMIT clause in
	the query. XXX: it's never shown in EXPLAIN!
	OPTION_FOUND_ROWS supersedes LIMIT and is taken into account.
      */
1571
      if (create_sort_index(thd, curr_join,
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			    curr_join->group_list ? 
			    curr_join->group_list : curr_join->order,
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			    curr_join->select_limit,
			    (select_options & OPTION_FOUND_ROWS ?
			     HA_POS_ERROR : unit->select_limit_cnt)))
1577
	DBUG_VOID_RETURN;
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    }
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  }
1580
  curr_join->having= curr_join->tmp_having;
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  thd->proc_info="Sending data";
1582
  error= thd->net.report_error ? -1 :
1583
    do_select(curr_join, curr_fields_list, NULL, procedure);
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  thd->limit_found_rows= curr_join->send_records;
  thd->examined_row_count= curr_join->examined_rows;
1586 1587
  DBUG_VOID_RETURN;
}
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1589

1590 1591 1592 1593 1594
/*
  Clean up join. Return error that hold JOIN.
*/

int
1595
JOIN::cleanup()
1596
{
1597
  DBUG_ENTER("JOIN::cleanup");
1598 1599 1600
  select_lex->join= 0;

  if (tmp_join)
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  {
    if (join_tab != tmp_join->join_tab)
    {
      JOIN_TAB *tab, *end;
      for (tab= join_tab, end= tab+tables ; tab != end ; tab++)
      {
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	tab->cleanup();
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      }
    }
    tmp_join->tmp_join= 0;
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    tmp_table_param.copy_field=0;
1612
    DBUG_RETURN(tmp_join->cleanup());
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  }
1614

1615
  lock=0;                                     // It's faster to unlock later
1616
  join_free(1);
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  if (exec_tmp_table1)
    free_tmp_table(thd, exec_tmp_table1);
  if (exec_tmp_table2)
    free_tmp_table(thd, exec_tmp_table2);
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  delete select;
  delete_dynamic(&keyuse);
  delete procedure;
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  for (SELECT_LEX_UNIT *lex_unit= select_lex->first_inner_unit();
       lex_unit != 0;
       lex_unit= lex_unit->next_unit())
1627
  {
1628
    error|= lex_unit->cleanup();
1629 1630
  }
  DBUG_RETURN(error);
1631 1632
}

1633

1634
int
1635
mysql_select(THD *thd, Item ***rref_pointer_array,
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	     TABLE_LIST *tables, uint wild_num, List<Item> &fields,
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	     COND *conds, uint og_num,  ORDER *order, ORDER *group,
	     Item *having, ORDER *proc_param, ulong select_options,
	     select_result *result, SELECT_LEX_UNIT *unit,
1640
	     SELECT_LEX *select_lex)
1641
{
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  int err;
  bool free_join= 1;
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  DBUG_ENTER("mysql_select");

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  JOIN *join;
1647
  if (select_lex->join != 0)
1648
  {
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    join= select_lex->join;
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    // is it single SELECT in derived table, called in derived table creation
    if (select_lex->linkage != DERIVED_TABLE_TYPE ||
	(select_options & SELECT_DESCRIBE))
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    {
1654
      if (select_lex->linkage != GLOBAL_OPTIONS_TYPE)
1655
      {
1656
	//here is EXPLAIN of subselect or derived table
1657
	if (join->change_result(result))
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	{
	  DBUG_RETURN(-1);
	}
1661
      }
1662
      else
1663
      {
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	if (join->prepare(rref_pointer_array, tables, wild_num,
			  conds, og_num, order, group, having, proc_param,
			  select_lex, unit))
	{
	  goto err;
	}
1670
      }
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    }
1672
    free_join= 0;
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    join->select_options= select_options;
1674
  }
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  else
  {
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    if (!(join= new JOIN(thd, fields, select_options, result)))
	DBUG_RETURN(-1);
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    thd->proc_info="init";
    thd->used_tables=0;                         // Updated by setup_fields
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    if (join->prepare(rref_pointer_array, tables, wild_num,
		      conds, og_num, order, group, having, proc_param,
1683
		      select_lex, unit))
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    {
1685
      goto err;
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    }
  }

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  if ((err= join->optimize()))
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  {
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    goto err;					// 1
  }
1693

1694
  if (thd->lex->describe & DESCRIBE_EXTENDED)
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  {
    join->conds_history= join->conds;
    join->having_history= (join->having?join->having:join->tmp_having);
  }

1700
  if (thd->net.report_error)
1701 1702 1703 1704
    goto err;

  join->exec();

1705
  if (thd->lex->describe & DESCRIBE_EXTENDED)
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  {
    select_lex->where= join->conds_history;
    select_lex->having= join->having_history;
  }

1711
err:
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  if (free_join)
  {
    thd->proc_info="end";
1715
    err= join->cleanup();
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    if (thd->net.report_error)
      err= -1;
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    delete join;
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    DBUG_RETURN(err);
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  }
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  DBUG_RETURN(join->error);
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}

/*****************************************************************************
1725 1726
  Create JOIN_TABS, make a guess about the table types,
  Approximate how many records will be used in each table
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*****************************************************************************/

1729 1730
static ha_rows get_quick_record_count(THD *thd, SQL_SELECT *select,
				      TABLE *table,
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				      const key_map *keys,ha_rows limit)
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{
  int error;
  DBUG_ENTER("get_quick_record_count");
  if (select)
  {
    select->head=table;
    table->reginfo.impossible_range=0;
1739 1740
    if ((error= select->test_quick_select(thd, *(key_map *)keys,(table_map) 0,
                                          limit, 0)) == 1)
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      DBUG_RETURN(select->quick->records);
    if (error == -1)
    {
      table->reginfo.impossible_range=1;
      DBUG_RETURN(0);
    }
    DBUG_PRINT("warning",("Couldn't use record count on const keypart"));
  }
  DBUG_RETURN(HA_POS_ERROR);			/* This shouldn't happend */
}


1753 1754 1755 1756 1757 1758 1759
/*
  Calculate the best possible join and initialize the join structure

  RETURN VALUES
  0	ok
  1	Fatal error
*/
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static bool
make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
1763
		     DYNAMIC_ARRAY *keyuse_array)
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{
  int error;
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  uint i,table_count,const_count,key;
  table_map found_const_table_map, all_table_map, found_ref, refs;
  key_map const_ref, eq_part;
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  TABLE **table_vector;
  JOIN_TAB *stat,*stat_end,*s,**stat_ref;
  KEYUSE *keyuse,*start_keyuse;
  table_map outer_join=0;
  JOIN_TAB *stat_vector[MAX_TABLES+1];
  DBUG_ENTER("make_join_statistics");

  table_count=join->tables;
1777 1778
  stat=(JOIN_TAB*) join->thd->calloc(sizeof(JOIN_TAB)*table_count);
  stat_ref=(JOIN_TAB**) join->thd->alloc(sizeof(JOIN_TAB*)*MAX_TABLES);
1779
  table_vector=(TABLE**) join->thd->alloc(sizeof(TABLE*)*(table_count*2));
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  if (!stat || !stat_ref || !table_vector)
    DBUG_RETURN(1);				// Eom /* purecov: inspected */

  join->best_ref=stat_vector;

  stat_end=stat+table_count;
1786
  found_const_table_map= all_table_map=0;
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  const_count=0;

  for (s=stat,i=0 ; tables ; s++,tables=tables->next,i++)
  {
    TABLE *table;
    stat_vector[i]=s;
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    s->keys.init();
    s->const_keys.init();
    s->checked_keys.init();
    s->needed_reg.init();
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    table_vector[i]=s->table=table=tables->table;
    table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);// record count
1799
    table->quick_keys.clear_all();
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    table->reginfo.join_tab=s;
    table->reginfo.not_exists_optimize=0;
    bzero((char*) table->const_key_parts, sizeof(key_part_map)*table->keys);
    all_table_map|= table->map;
1804
    s->join=join;
1805
    s->info=0;					// For describe
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    if ((s->on_expr=tables->on_expr))
    {
1808
      /* Left join */
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      if (!table->file->records)
      {						// Empty table
1811
	s->key_dependent=s->dependent=0;	// Ignore LEFT JOIN depend.
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	set_position(join,const_count++,s,(KEYUSE*) 0);
	continue;
      }
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      s->key_dependent=s->dependent=
	s->on_expr->used_tables() & ~(table->map);
1817 1818 1819 1820
      if (table->outer_join & JOIN_TYPE_LEFT)
	s->dependent|=stat_vector[i-1]->dependent | table_vector[i-1]->map;
      if (tables->outer_join & JOIN_TYPE_RIGHT)
	s->dependent|=tables->next->table->map;
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      outer_join|=table->map;
      continue;
    }
    if (tables->straight)			// We don't have to move this
      s->dependent= table_vector[i-1]->map | stat_vector[i-1]->dependent;
    else
      s->dependent=(table_map) 0;
    s->key_dependent=(table_map) 0;
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    if ((table->system || table->file->records <= 1) && ! s->dependent &&
1830
	!(table->file->table_flags() & HA_NOT_EXACT_COUNT) &&
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        !table->fulltext_searched)
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    {
      set_position(join,const_count++,s,(KEYUSE*) 0);
    }
  }
  stat_vector[i]=0;
1837
  join->outer_join=outer_join;
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1838 1839

  /*
1840 1841 1842 1843
    If outer join: Re-arrange tables in stat_vector so that outer join
    tables are after all tables it is dependent of.
    For example: SELECT * from A LEFT JOIN B ON B.c=C.c, C WHERE A.C=C.C
    Will shift table B after table C.
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  */
  if (outer_join)
  {
    table_map used_tables=0L;
    for (i=0 ; i < join->tables-1 ; i++)
    {
      if (stat_vector[i]->dependent & ~used_tables)
      {
	JOIN_TAB *save= stat_vector[i];
	uint j;
	for (j=i+1;
	     j < join->tables && stat_vector[j]->dependent & ~used_tables;
	     j++)
	{
	  JOIN_TAB *tmp=stat_vector[j];		// Move element up
	  stat_vector[j]=save;
	  save=tmp;
	}
	if (j == join->tables)
	{
	  join->tables=0;			// Don't use join->table
	  my_error(ER_WRONG_OUTER_JOIN,MYF(0));
	  DBUG_RETURN(1);
	}
	stat_vector[i]=stat_vector[j];
	stat_vector[j]=save;
      }
      used_tables|= stat_vector[i]->table->map;
    }
  }

  if (conds || outer_join)
1876 1877
    if (update_ref_and_keys(join->thd, keyuse_array, stat, join->tables,
                            conds, ~outer_join, join->select_lex))
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      DBUG_RETURN(1);

1880
  /* Read tables with 0 or 1 rows (system tables) */
1881
  join->const_table_map= 0;
1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899

  for (POSITION *p_pos=join->positions, *p_end=p_pos+const_count;
       p_pos < p_end ;
       p_pos++)
  {
    int tmp;
    s= p_pos->table;
    s->type=JT_SYSTEM;
    join->const_table_map|=s->table->map;
    if ((tmp=join_read_const_table(s, p_pos)))
    {
      if (tmp > 0)
	DBUG_RETURN(1);			// Fatal error
    }
    else
      found_const_table_map|= s->table->map;
  }

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  /* loop until no more const tables are found */
1901
  int ref_changed;
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  do
  {
1904
    ref_changed = 0;
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    found_ref=0;
1906 1907 1908 1909 1910 1911 1912

    /*
      We only have to loop from stat_vector + const_count as
      set_position() will move all const_tables first in stat_vector
    */

    for (JOIN_TAB **pos=stat_vector+const_count ; (s= *pos) ; pos++)
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    {
1914
      TABLE *table=s->table;
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      if (s->dependent)				// If dependent on some table
      {
1917
	// All dep. must be constants
1918
	if (s->dependent & ~(found_const_table_map))
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	  continue;
1920
	if (table->file->records <= 1L &&
1921
	    !(table->file->table_flags() & HA_NOT_EXACT_COUNT))
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	{					// system table
1923
	  int tmp= 0;
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	  s->type=JT_SYSTEM;
1925
	  join->const_table_map|=table->map;
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	  set_position(join,const_count++,s,(KEYUSE*) 0);
1927
	  if ((tmp= join_read_const_table(s,join->positions+const_count-1)))
1928 1929 1930 1931 1932 1933
	  {
	    if (tmp > 0)
	      DBUG_RETURN(1);			// Fatal error
	  }
	  else
	    found_const_table_map|= table->map;
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	  continue;
	}
      }
      /* check if table can be read by key or table only uses const refs */
      if ((keyuse=s->keyuse))
      {
	s->type= JT_REF;
	while (keyuse->table == table)
	{
	  start_keyuse=keyuse;
	  key=keyuse->key;
1945
	  s->keys.set_bit(key);               // QQ: remove this ?
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1947 1948 1949
	  refs=0;
          const_ref.clear_all();
	  eq_part.clear_all();
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	  do
	  {
1952
	    if (keyuse->val->type() != Item::NULL_ITEM && !keyuse->optimize)
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	    {
1954
	      if (!((~found_const_table_map) & keyuse->used_tables))
1955
		const_ref.set_bit(keyuse->keypart);
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	      else
		refs|=keyuse->used_tables;
1958
	      eq_part.set_bit(keyuse->keypart);
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	    }
	    keyuse++;
	  } while (keyuse->table == table && keyuse->key == key);

1963
	  if (eq_part.is_prefix(table->key_info[key].key_parts) &&
1964 1965
	      ((table->key_info[key].flags & (HA_NOSAME | HA_END_SPACE_KEY)) ==
	       HA_NOSAME) &&
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              !table->fulltext_searched)
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	  {
	    if (const_ref == eq_part)
	    {					// Found everything for ref.
1970 1971
	      int tmp;
	      ref_changed = 1;
1972
	      s->type= JT_CONST;
1973
	      join->const_table_map|=table->map;
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	      set_position(join,const_count++,s,start_keyuse);
1975
	      if (create_ref_for_key(join, s, start_keyuse,
1976
				     found_const_table_map))
1977 1978 1979 1980 1981 1982 1983 1984 1985
		DBUG_RETURN(1);
	      if ((tmp=join_read_const_table(s,
					     join->positions+const_count-1)))
	      {
		if (tmp > 0)
		  DBUG_RETURN(1);			// Fatal error
	      }
	      else
		found_const_table_map|= table->map;
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	      break;
	    }
	    else
	      found_ref|= refs;		// Table is const if all refs are const
	  }
	}
      }
    }
1994
  } while (join->const_table_map & found_ref && ref_changed);
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  /* Calc how many (possible) matched records in each table */

  for (s=stat ; s < stat_end ; s++)
  {
    if (s->type == JT_SYSTEM || s->type == JT_CONST)
    {
      /* Only one matching row */
      s->found_records=s->records=s->read_time=1; s->worst_seeks=1.0;
      continue;
    }
    /* Approximate found rows and time to read them */
    s->found_records=s->records=s->table->file->records;
2008
    s->read_time=(ha_rows) s->table->file->scan_time();
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2010 2011
    /*
      Set a max range of how many seeks we can expect when using keys
2012 2013
      This is can't be to high as otherwise we are likely to use
      table scan.
2014
    */
2015 2016
    s->worst_seeks= min((double) s->found_records / 10,
			(double) s->read_time*3);
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    if (s->worst_seeks < 2.0)			// Fix for small tables
      s->worst_seeks=2.0;

2020
    if (! s->const_keys.is_clear_all())
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    {
      ha_rows records;
2023 2024 2025 2026 2027
      SQL_SELECT *select;
      select= make_select(s->table, found_const_table_map,
			  found_const_table_map,
			  s->on_expr ? s->on_expr : conds,
			  &error);
2028
      records= get_quick_record_count(join->thd, select, s->table,
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				      &s->const_keys, join->row_limit);
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      s->quick=select->quick;
      s->needed_reg=select->needed_reg;
      select->quick=0;
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      if (records == 0 && s->table->reginfo.impossible_range)
      {
	/*
	  Impossible WHERE or ON expression
	  In case of ON, we mark that the we match one empty NULL row.
	  In case of WHERE, don't set found_const_table_map to get the
	  caller to abort with a zero row result.
	*/
	join->const_table_map|= s->table->map;
	set_position(join,const_count++,s,(KEYUSE*) 0);
	s->type= JT_CONST;
	if (s->on_expr)
	{
	  /* Generate empty row */
	  s->info= "Impossible ON condition";
	  found_const_table_map|= s->table->map;
	  s->type= JT_CONST;
	  mark_as_null_row(s->table);		// All fields are NULL
	}
      }
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      if (records != HA_POS_ERROR)
      {
2055
	s->found_records=records;
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	s->read_time= (ha_rows) (s->quick ? s->quick->read_time : 0.0);
      }
2058
      delete select;
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    }
  }

  /* Find best combination and return it */
  join->join_tab=stat;
  join->map2table=stat_ref;
  join->table= join->all_tables=table_vector;
  join->const_tables=const_count;
2067
  join->found_const_table_map=found_const_table_map;
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  if (join->const_tables != join->tables)
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  {
    optimize_keyuse(join, keyuse_array);
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    find_best_combination(join,all_table_map & ~join->const_table_map);
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  }
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  else
  {
    memcpy((gptr) join->best_positions,(gptr) join->positions,
	   sizeof(POSITION)*join->const_tables);
    join->best_read=1.0;
  }
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  DBUG_RETURN(join->thd->killed || get_best_combination(join));
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}


/*****************************************************************************
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  Check with keys are used and with tables references with tables
  Updates in stat:
	  keys	     Bitmap of all used keys
	  const_keys Bitmap of all keys with may be used with quick_select
	  keyuse     Pointer to possible keys
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*****************************************************************************/

typedef struct key_field_t {		// Used when finding key fields
  Field		*field;
  Item		*val;			// May be empty if diff constant
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  uint		level;
  uint		optimize;
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  bool		eq_func;
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  /*
    If true, the condition this struct represents will not be satisfied
    when val IS NULL.
  */
  bool          null_rejecting; 
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} KEY_FIELD;

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/* Values in optimize */
#define KEY_OPTIMIZE_EXISTS		1
#define KEY_OPTIMIZE_REF_OR_NULL	2

/*
  Merge new key definitions to old ones, remove those not used in both

  This is called for OR between different levels
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  To be able to do 'ref_or_null' we merge a comparison of a column
  and 'column IS NULL' to one test.  This is useful for sub select queries
  that are internally transformed to something like:

  SELECT * FROM t1 WHERE t1.key=outer_ref_field or t1.key IS NULL 
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  KEY_FIELD::null_rejecting is processed as follows:
  result has null_rejecting=true if it is set for both ORed references.
  for example:
    (t2.key = t1.field OR t2.key  =  t1.field) -> null_rejecting=true
    (t2.key = t1.field OR t2.key <=> t1.field) -> null_rejecting=false
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*/
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static KEY_FIELD *
merge_key_fields(KEY_FIELD *start,KEY_FIELD *new_fields,KEY_FIELD *end,
		 uint and_level)
{
  if (start == new_fields)
    return start;				// Impossible or
  if (new_fields == end)
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    return start;				// No new fields, skip all
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  KEY_FIELD *first_free=new_fields;

  /* Mark all found fields in old array */
  for (; new_fields != end ; new_fields++)
  {
    for (KEY_FIELD *old=start ; old != first_free ; old++)
    {
      if (old->field == new_fields->field)
      {
	if (new_fields->val->used_tables())
	{
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	  /*
	    If the value matches, we can use the key reference.
	    If not, we keep it until we have examined all new values
	  */
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	  if (old->val->eq(new_fields->val, old->field->binary()))
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	  {
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	    old->level= and_level;
	    old->optimize= ((old->optimize & new_fields->optimize &
			     KEY_OPTIMIZE_EXISTS) |
			    ((old->optimize | new_fields->optimize) &
			     KEY_OPTIMIZE_REF_OR_NULL));
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            old->null_rejecting= (old->null_rejecting &&
                                  new_fields->null_rejecting);
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	  }
	}
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	else if (old->eq_func && new_fields->eq_func &&
		 old->val->eq(new_fields->val, old->field->binary()))
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	{
	  old->level= and_level;
	  old->optimize= ((old->optimize & new_fields->optimize &
			   KEY_OPTIMIZE_EXISTS) |
			  ((old->optimize | new_fields->optimize) &
			   KEY_OPTIMIZE_REF_OR_NULL));
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          old->null_rejecting= (old->null_rejecting &&
                                new_fields->null_rejecting);
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	}
	else if (old->eq_func && new_fields->eq_func &&
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		 ((!old->val->used_tables() && old->val->is_null()) || 
                  new_fields->val->is_null()))
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	{
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	  /* field = expression OR field IS NULL */
	  old->level= and_level;
	  old->optimize= KEY_OPTIMIZE_REF_OR_NULL;
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	  /*
            Remember the NOT NULL value unless the value does not depend
            on other tables.
          */
	  if (!old->val->used_tables() && old->val->is_null())
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	    old->val= new_fields->val;
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          /* The referred expression can be NULL: */ 
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          old->null_rejecting= 0;
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	}
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	else
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	{
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	  /*
	    We are comparing two different const.  In this case we can't
	    use a key-lookup on this so it's better to remove the value
	    and let the range optimzier handle it
	  */
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	  if (old == --first_free)		// If last item
	    break;
	  *old= *first_free;			// Remove old value
	  old--;				// Retry this value
	}
      }
    }
  }
  /* Remove all not used items */
  for (KEY_FIELD *old=start ; old != first_free ;)
  {
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    if (old->level != and_level)
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    {						// Not used in all levels
      if (old == --first_free)
	break;
      *old= *first_free;			// Remove old value
      continue;
    }
    old++;
  }
  return first_free;
}


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/*
  Add a possible key to array of possible keys if it's usable as a key

  SYNPOSIS
    add_key_field()
    key_fields			Pointer to add key, if usable
    and_level			And level, to be stored in KEY_FIELD
    field			Field used in comparision
    eq_func			True if we used =, <=> or IS NULL
    value			Value used for comparison with field
    usable_tables		Tables which can be used for key optimization

  NOTES
    If we are doing a NOT NULL comparison on a NOT NULL field in a outer join
    table, we store this to be able to do not exists optimization later.

  RETURN
    *key_fields is incremented if we stored a key in the array
*/

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static void
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add_key_field(KEY_FIELD **key_fields,uint and_level, Item_func *cond,
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	      Field *field,bool eq_func,Item **value, uint num_values,
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	      table_map usable_tables)
{
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  uint exists_optimize= 0;
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  if (!(field->flags & PART_KEY_FLAG))
  {
    // Don't remove column IS NULL on a LEFT JOIN table
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    if (!eq_func || (*value)->type() != Item::NULL_ITEM ||
        !field->table->maybe_null || field->null_ptr)
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      return;					// Not a key. Skip it
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    exists_optimize= KEY_OPTIMIZE_EXISTS;
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  }
  else
  {
    table_map used_tables=0;
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    bool optimizable=0;
    for (uint i=0; i<num_values; i++)
    {
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      used_tables|=(value[i])->used_tables();
      if (!((value[i])->used_tables() & (field->table->map | RAND_TABLE_BIT)))
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        optimizable=1;
    }
    if (!optimizable)
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      return;
    if (!(usable_tables & field->table->map))
    {
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      if (!eq_func || (*value)->type() != Item::NULL_ITEM ||
          !field->table->maybe_null || field->null_ptr)
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	return;					// Can't use left join optimize
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      exists_optimize= KEY_OPTIMIZE_EXISTS;
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    }
    else
    {
      JOIN_TAB *stat=field->table->reginfo.join_tab;
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      key_map possible_keys=field->key_start;
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      possible_keys.intersect(field->table->keys_in_use_for_query);
      stat[0].keys.merge(possible_keys);             // Add possible keys
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      /*
	Save the following cases:
	Field op constant
	Field LIKE constant where constant doesn't start with a wildcard
	Field = field2 where field2 is in a different table
	Field op formula
	Field IS NULL
	Field IS NOT NULL
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         Field BETWEEN ...
         Field IN ...
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      */
      stat[0].key_dependent|=used_tables;

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      bool is_const=1;
      for (uint i=0; i<num_values; i++)
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        is_const&= value[i]->const_item();
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      if (is_const)
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        stat[0].const_keys.merge(possible_keys);
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      /*
	We can't always use indexes when comparing a string index to a
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	number. cmp_type() is checked to allow compare of dates to numbers.
        eq_func is NEVER true when num_values > 1
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       */
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      if (!eq_func)
        return;
      if (field->result_type() == STRING_RESULT)
      {
        if ((*value)->result_type() != STRING_RESULT)
        {
          if (field->cmp_type() != (*value)->result_type())
            return;
        }
        else
        {
          /*
            We can't use indexes if the effective collation
            of the operation differ from the field collation.
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            We can also not used index on a text column, as the column may
            contain 'x' 'x\t' 'x ' and 'read_next_same' will stop after
            'x' when searching for WHERE col='x '
          */
          if (field->cmp_type() == STRING_RESULT &&
              (((Field_str*)field)->charset() != cond->compare_collation() ||
               ((*value)->type() != Item::NULL_ITEM &&
                (field->flags & BLOB_FLAG) && !field->binary())))
            return;
        }
      }
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    }
  }
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  DBUG_ASSERT(num_values == 1);
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  /*
    For the moment eq_func is always true. This slot is reserved for future
    extensions where we want to remembers other things than just eq comparisons
  */
  DBUG_ASSERT(eq_func);
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  /* Store possible eq field */
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  (*key_fields)->field=		field;
  (*key_fields)->eq_func=	eq_func;
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  (*key_fields)->val=		*value;
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  (*key_fields)->level=		and_level;
  (*key_fields)->optimize=	exists_optimize;
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  /*
    If the condition has form "tbl.keypart = othertbl.field" and 
    othertbl.field can be NULL, there will be no matches if othertbl.field 
    has NULL value.
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    We use null_rejecting in add_not_null_conds() to add
    'othertbl.field IS NOT NULL' to tab->select_cond.
2350
  */
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  (*key_fields)->null_rejecting= ((cond->functype() == Item_func::EQ_FUNC) &&
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                                 ((*value)->type() == Item::FIELD_ITEM) &&
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                                  ((Item_field*)*value)->field->maybe_null());
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  (*key_fields)++;
}

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/*
  SYNOPSIS
    add_key_fields()
      key_fields      Add KEY_FIELD entries to this array (and move the 
                      pointer)
      and_level       AND-level (a value that is different for every n-way
                      AND operation)
      cond            Condition to analyze
      usable_tables   Value to pass to add_key_field
*/
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static void
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add_key_fields(KEY_FIELD **key_fields,uint *and_level,
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	       COND *cond, table_map usable_tables)
{
  if (cond->type() == Item_func::COND_ITEM)
  {
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    List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list());
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    KEY_FIELD *org_key_fields= *key_fields;

    if (((Item_cond*) cond)->functype() == Item_func::COND_AND_FUNC)
    {
      Item *item;
      while ((item=li++))
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	add_key_fields(key_fields,and_level,item,usable_tables);
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      for (; org_key_fields != *key_fields ; org_key_fields++)
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	org_key_fields->level= *and_level;
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    }
    else
    {
      (*and_level)++;
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      add_key_fields(key_fields,and_level,li++,usable_tables);
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      Item *item;
      while ((item=li++))
      {
	KEY_FIELD *start_key_fields= *key_fields;
	(*and_level)++;
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	add_key_fields(key_fields,and_level,item,usable_tables);
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	*key_fields=merge_key_fields(org_key_fields,start_key_fields,
				     *key_fields,++(*and_level));
      }
    }
    return;
  }
  /* If item is of type 'field op field/constant' add it to key_fields */

  if (cond->type() != Item::FUNC_ITEM)
    return;
  Item_func *cond_func= (Item_func*) cond;
  switch (cond_func->select_optimize()) {
  case Item_func::OPTIMIZE_NONE:
    break;
  case Item_func::OPTIMIZE_KEY:
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    // BETWEEN, IN, NOT
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    if (cond_func->key_item()->real_item()->type() == Item::FIELD_ITEM &&
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	!(cond_func->used_tables() & OUTER_REF_TABLE_BIT))
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      add_key_field(key_fields,*and_level,cond_func,
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		    ((Item_field*)(cond_func->key_item()->real_item()))->field,
                    cond_func->argument_count() == 2 &&
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                    cond_func->functype() == Item_func::IN_FUNC &&
                    !((Item_func_in*)cond_func)->negated,
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                    cond_func->arguments()+1, cond_func->argument_count()-1,
                    usable_tables);
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    break;
  case Item_func::OPTIMIZE_OP:
  {
    bool equal_func=(cond_func->functype() == Item_func::EQ_FUNC ||
		     cond_func->functype() == Item_func::EQUAL_FUNC);

2425
    if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM &&
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	!(cond_func->arguments()[0]->used_tables() & OUTER_REF_TABLE_BIT))
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    {
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      add_key_field(key_fields,*and_level,cond_func,
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		    ((Item_field*) (cond_func->arguments()[0])->real_item())
		    ->field,
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		    equal_func,
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                    cond_func->arguments()+1, 1, usable_tables);
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    }
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    if (cond_func->arguments()[1]->real_item()->type() == Item::FIELD_ITEM &&
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	cond_func->functype() != Item_func::LIKE_FUNC &&
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	!(cond_func->arguments()[1]->used_tables() & OUTER_REF_TABLE_BIT))
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    {
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      add_key_field(key_fields,*and_level,cond_func,
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		    ((Item_field*) (cond_func->arguments()[1])->real_item())
		    ->field,
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		    equal_func,
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		    cond_func->arguments(),1,usable_tables);
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    }
    break;
  }
  case Item_func::OPTIMIZE_NULL:
    /* column_name IS [NOT] NULL */
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    if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM &&
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	!(cond_func->used_tables() & OUTER_REF_TABLE_BIT))
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    {
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      Item *tmp=new Item_null;
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      if (unlikely(!tmp))                       // Should never be true
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	return;
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      add_key_field(key_fields,*and_level,cond_func,
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		    ((Item_field*) (cond_func->arguments()[0])->real_item())
		    ->field,
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		    cond_func->functype() == Item_func::ISNULL_FUNC,
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		    &tmp, 1, usable_tables);
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    }
    break;
  }
  return;
}

/*
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  Add all keys with uses 'field' for some keypart
  If field->and_level != and_level then only mark key_part as const_part
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*/

static uint
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max_part_bit(key_part_map bits)
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{
  uint found;
  for (found=0; bits & 1 ; found++,bits>>=1) ;
  return found;
}

static void
add_key_part(DYNAMIC_ARRAY *keyuse_array,KEY_FIELD *key_field)
{
  Field *field=key_field->field;
  TABLE *form= field->table;
  KEYUSE keyuse;

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  if (key_field->eq_func && !(key_field->optimize & KEY_OPTIMIZE_EXISTS))
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  {
    for (uint key=0 ; key < form->keys ; key++)
    {
2489
      if (!(form->keys_in_use_for_query.is_set(key)))
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	continue;
      if (form->key_info[key].flags & HA_FULLTEXT)
	continue;    // ToDo: ft-keys in non-ft queries.   SerG

      uint key_parts= (uint) form->key_info[key].key_parts;
      for (uint part=0 ; part <  key_parts ; part++)
      {
	if (field->eq(form->key_info[key].key_part[part].field))
	{
	  keyuse.table= field->table;
	  keyuse.val =  key_field->val;
	  keyuse.key =  key;
	  keyuse.keypart=part;
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	  keyuse.keypart_map= (key_part_map) 1 << part;
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	  keyuse.used_tables=key_field->val->used_tables();
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	  keyuse.optimize= key_field->optimize & KEY_OPTIMIZE_REF_OR_NULL;
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          keyuse.null_rejecting= key_field->null_rejecting;
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	  VOID(insert_dynamic(keyuse_array,(gptr) &keyuse));
	}
      }
    }
  }
}

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#define FT_KEYPART   (MAX_REF_PARTS+10)

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static void
add_ft_keys(DYNAMIC_ARRAY *keyuse_array,
            JOIN_TAB *stat,COND *cond,table_map usable_tables)
{
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  Item_func_match *cond_func=NULL;
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  if (!cond)
    return;

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  if (cond->type() == Item::FUNC_ITEM)
  {
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    Item_func *func=(Item_func *)cond;
    Item_func::Functype functype=  func->functype();
    if (functype == Item_func::FT_FUNC)
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      cond_func=(Item_func_match *)cond;
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    else if (func->arg_count == 2)
    {
      Item_func *arg0=(Item_func *)(func->arguments()[0]),
                *arg1=(Item_func *)(func->arguments()[1]);
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      if (arg1->const_item()  &&
          ((functype == Item_func::GE_FUNC && arg1->val()> 0) ||
           (functype == Item_func::GT_FUNC && arg1->val()>=0))  &&
           arg0->type() == Item::FUNC_ITEM            &&
           arg0->functype() == Item_func::FT_FUNC)
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        cond_func=(Item_func_match *) arg0;
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      else if (arg0->const_item() &&
               ((functype == Item_func::LE_FUNC && arg0->val()> 0) ||
                (functype == Item_func::LT_FUNC && arg0->val()>=0)) &&
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                arg1->type() == Item::FUNC_ITEM          &&
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                arg1->functype() == Item_func::FT_FUNC)
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        cond_func=(Item_func_match *) arg1;
    }
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  }
  else if (cond->type() == Item::COND_ITEM)
  {
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    List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list());
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    if (((Item_cond*) cond)->functype() == Item_func::COND_AND_FUNC)
    {
      Item *item;
      while ((item=li++))
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        add_ft_keys(keyuse_array,stat,item,usable_tables);
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    }
  }

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  if (!cond_func || cond_func->key == NO_SUCH_KEY ||
      !(usable_tables & cond_func->table->map))
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    return;
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  KEYUSE keyuse;
  keyuse.table= cond_func->table;
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  keyuse.val =  cond_func;
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  keyuse.key =  cond_func->key;
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  keyuse.keypart= FT_KEYPART;
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  keyuse.used_tables=cond_func->key_item()->used_tables();
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  keyuse.optimize= 0;
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  keyuse.keypart_map= 0;
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  VOID(insert_dynamic(keyuse_array,(gptr) &keyuse));
}

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static int
sort_keyuse(KEYUSE *a,KEYUSE *b)
{
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  int res;
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  if (a->table->tablenr != b->table->tablenr)
    return (int) (a->table->tablenr - b->table->tablenr);
  if (a->key != b->key)
    return (int) (a->key - b->key);
  if (a->keypart != b->keypart)
    return (int) (a->keypart - b->keypart);
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  // Place const values before other ones
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  if ((res= test((a->used_tables & ~OUTER_REF_TABLE_BIT)) -
       test((b->used_tables & ~OUTER_REF_TABLE_BIT))))
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    return res;
  /* Place rows that are not 'OPTIMIZE_REF_OR_NULL' first */
  return (int) ((a->optimize & KEY_OPTIMIZE_REF_OR_NULL) -
		(b->optimize & KEY_OPTIMIZE_REF_OR_NULL));
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}


/*
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  Update keyuse array with all possible keys we can use to fetch rows
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  SYNOPSIS
    update_ref_and_keys()
      thd 
      keyuse     OUT Put here ordered array of KEYUSE structures
      join_tab       Array in tablenr_order
      tables         Number of tables in join
      cond           WHERE condition (note that the function analyzes 
                     join_tab[i]->on_expr too)
      normal_tables  tables not inner w.r.t some outer join (ones for which
                     we can make ref access based the WHERE clause)
      select_lex     current SELECT
      
  RETURN 
   0 - OK
   1 - Out of memory.
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*/

static bool
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update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,JOIN_TAB *join_tab,
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		    uint tables, COND *cond, table_map normal_tables,
		    SELECT_LEX *select_lex)
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{
  uint	and_level,i,found_eq_constant;
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  KEY_FIELD *key_fields, *end, *field;
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  if (!(key_fields=(KEY_FIELD*)
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	thd->alloc(sizeof(key_fields[0])*
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		   (thd->lex->current_select->cond_count+1)*2)))
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    return TRUE; /* purecov: inspected */
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  and_level= 0;
  field= end= key_fields;
  if (my_init_dynamic_array(keyuse,sizeof(KEYUSE),20,64))
    return TRUE;
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  if (cond)
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  {
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    add_key_fields(&end,&and_level,cond,normal_tables);
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    for (; field != end ; field++)
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    {
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      add_key_part(keyuse,field);
      /* Mark that we can optimize LEFT JOIN */
      if (field->val->type() == Item::NULL_ITEM &&
	  !field->field->real_maybe_null())
	field->field->table->reginfo.not_exists_optimize=1;
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    }
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  }
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  for (i=0 ; i < tables ; i++)
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  {
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    if (join_tab[i].on_expr)
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    {
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      add_key_fields(&end,&and_level,join_tab[i].on_expr,
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		     join_tab[i].table->map);
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    }
  }
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  /* fill keyuse with found key parts */
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  for ( ; field != end ; field++)
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    add_key_part(keyuse,field);
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  if (select_lex->ftfunc_list->elements)
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  {
    add_ft_keys(keyuse,join_tab,cond,normal_tables);
  }

  /*
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    Special treatment for ft-keys.
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    Remove the following things from KEYUSE:
    - ref if there is a keypart which is a ref and a const.
    - keyparts without previous keyparts.
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  */
  if (keyuse->elements)
  {
    KEYUSE end,*prev,*save_pos,*use;

    qsort(keyuse->buffer,keyuse->elements,sizeof(KEYUSE),
	  (qsort_cmp) sort_keyuse);

    bzero((char*) &end,sizeof(end));		/* Add for easy testing */
    VOID(insert_dynamic(keyuse,(gptr) &end));

    use=save_pos=dynamic_element(keyuse,0,KEYUSE*);
    prev=&end;
    found_eq_constant=0;
    for (i=0 ; i < keyuse->elements-1 ; i++,use++)
    {
      if (!use->used_tables)
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	use->table->const_key_parts[use->key]|= use->keypart_map;
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      if (use->keypart != FT_KEYPART)
      {
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	if (use->key == prev->key && use->table == prev->table)
	{
	  if (prev->keypart+1 < use->keypart ||
	      prev->keypart == use->keypart && found_eq_constant)
	    continue;				/* remove */
	}
	else if (use->keypart != 0)		// First found must be 0
	  continue;
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      }

      *save_pos= *use;
      prev=use;
      found_eq_constant= !use->used_tables;
      /* Save ptr to first use */
      if (!use->table->reginfo.join_tab->keyuse)
	use->table->reginfo.join_tab->keyuse=save_pos;
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      use->table->reginfo.join_tab->checked_keys.set_bit(use->key);
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      save_pos++;
    }
    i=(uint) (save_pos-(KEYUSE*) keyuse->buffer);
    VOID(set_dynamic(keyuse,(gptr) &end,i));
    keyuse->elements=i;
  }
  return FALSE;
}

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/*
  Update some values in keyuse for faster find_best_combination() loop
*/

static void optimize_keyuse(JOIN *join, DYNAMIC_ARRAY *keyuse_array)
{
  KEYUSE *end,*keyuse= dynamic_element(keyuse_array, 0, KEYUSE*);

  for (end= keyuse+ keyuse_array->elements ; keyuse < end ; keyuse++)
  {
    table_map map;
    /*
      If we find a ref, assume this table matches a proportional
      part of this table.
      For example 100 records matching a table with 5000 records
      gives 5000/100 = 50 records per key
      Constant tables are ignored.
      To avoid bad matches, we don't make ref_table_rows less than 100.
    */
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    keyuse->ref_table_rows= ~(ha_rows) 0;	// If no ref
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    if (keyuse->used_tables &
	(map= (keyuse->used_tables & ~join->const_table_map &
	       ~OUTER_REF_TABLE_BIT)))
    {
      uint tablenr;
      for (tablenr=0 ; ! (map & 1) ; map>>=1, tablenr++) ;
      if (map == 1)			// Only one table
      {
	TABLE *tmp_table=join->all_tables[tablenr];
	keyuse->ref_table_rows= max(tmp_table->file->records, 100);
      }
    }
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    /*
      Outer reference (external field) is constant for single executing
      of subquery
    */
    if (keyuse->used_tables == OUTER_REF_TABLE_BIT)
      keyuse->ref_table_rows= 1;
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  }
}

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/*****************************************************************************
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  Go through all combinations of not marked tables and find the one
  which uses least records
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*****************************************************************************/

/* Save const tables first as used tables */

static void
set_position(JOIN *join,uint idx,JOIN_TAB *table,KEYUSE *key)
{
  join->positions[idx].table= table;
  join->positions[idx].key=key;
  join->positions[idx].records_read=1.0;	/* This is a const table */

  /* Move the const table as down as possible in best_ref */
  JOIN_TAB **pos=join->best_ref+idx+1;
  JOIN_TAB *next=join->best_ref[idx];
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  for (;next != table ; pos++)
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  {
    JOIN_TAB *tmp=pos[0];
    pos[0]=next;
    next=tmp;
  }
  join->best_ref[idx]=table;
}


static void
find_best_combination(JOIN *join, table_map rest_tables)
{
  DBUG_ENTER("find_best_combination");
  join->best_read=DBL_MAX;
  find_best(join,rest_tables, join->const_tables,1.0,0.0);
  DBUG_VOID_RETURN;
}


static void
find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
	  double read_time)
{
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  ha_rows rec;
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  double tmp;
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  THD *thd= join->thd;
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  if (!rest_tables)
  {
    DBUG_PRINT("best",("read_time: %g  record_count: %g",read_time,
		       record_count));

    read_time+=record_count/(double) TIME_FOR_COMPARE;
    if (join->sort_by_table &&
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	join->sort_by_table !=
	join->positions[join->const_tables].table->table)
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      read_time+=record_count;			// We have to make a temp table
    if (read_time < join->best_read)
    {
      memcpy((gptr) join->best_positions,(gptr) join->positions,
	     sizeof(POSITION)*idx);
      join->best_read=read_time;
    }
    return;
  }
  if (read_time+record_count/(double) TIME_FOR_COMPARE >= join->best_read)
    return;					/* Found better before */

  JOIN_TAB *s;
  double best_record_count=DBL_MAX,best_read_time=DBL_MAX;
  for (JOIN_TAB **pos=join->best_ref+idx ; (s=*pos) ; pos++)
  {
    table_map real_table_bit=s->table->map;
    if ((rest_tables & real_table_bit) && !(rest_tables & s->dependent))
    {
      double best,best_time,records;
      best=best_time=records=DBL_MAX;
      KEYUSE *best_key=0;
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      uint best_max_key_part=0;
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      my_bool found_constraint= 0;
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      if (s->keyuse)
      {						/* Use key if possible */
	TABLE *table=s->table;
	KEYUSE *keyuse,*start_key=0;
	double best_records=DBL_MAX;
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	uint max_key_part=0;
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	/* Test how we can use keys */
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	rec= s->records/MATCHING_ROWS_IN_OTHER_TABLE;  // Assumed records/key
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	for (keyuse=s->keyuse ; keyuse->table == table ;)
	{
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	  key_part_map found_part=0;
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	  table_map found_ref=0;
	  uint key=keyuse->key;
	  KEY *keyinfo=table->key_info+key;
          bool ft_key=(keyuse->keypart == FT_KEYPART);
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	  uint found_ref_or_null= 0;
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	  /* Calculate how many key segments of the current key we can use */
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	  start_key=keyuse;
	  do
	  {
            uint keypart=keyuse->keypart;
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            table_map best_part_found_ref= 0;
            double best_prev_record_reads= DBL_MAX;
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	    do
	    {
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	      if (!(rest_tables & keyuse->used_tables) &&
		  !(found_ref_or_null & keyuse->optimize))
	      {
		found_part|=keyuse->keypart_map;
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                double tmp= prev_record_reads(join,
					      (found_ref |
					       keyuse->used_tables));
                if (tmp < best_prev_record_reads)
                {
                  best_part_found_ref= keyuse->used_tables;
                  best_prev_record_reads= tmp;
                }
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		if (rec > keyuse->ref_table_rows)
		  rec= keyuse->ref_table_rows;
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		/*
		  If there is one 'key_column IS NULL' expression, we can
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		  use this ref_or_null optimisation of this field
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		*/
		found_ref_or_null|= (keyuse->optimize &
				     KEY_OPTIMIZE_REF_OR_NULL);
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              }
	      keyuse++;
	    } while (keyuse->table == table && keyuse->key == key &&
		     keyuse->keypart == keypart);
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	    found_ref|= best_part_found_ref;
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	  } while (keyuse->table == table && keyuse->key == key);

	  /*
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	    Assume that that each key matches a proportional part of table.
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	  */
          if (!found_part && !ft_key)
	    continue;				// Nothing usable found
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	  if (rec < MATCHING_ROWS_IN_OTHER_TABLE)
	    rec= MATCHING_ROWS_IN_OTHER_TABLE;	// Fix for small tables
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          /*
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	    ft-keys require special treatment
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          */
          if (ft_key)
          {
            /*
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	      Really, there should be records=0.0 (yes!)
	      but 1.0 would be probably safer
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            */
            tmp=prev_record_reads(join,found_ref);
            records=1.0;
          }
          else
          {
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	  found_constraint= 1;
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	  /*
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	    Check if we found full key
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	  */
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	  if (found_part == PREV_BITS(uint,keyinfo->key_parts) &&
	      !found_ref_or_null)
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	  {				/* use eq key */
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	    max_key_part= (uint) ~0;
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	    if ((keyinfo->flags & (HA_NOSAME | HA_NULL_PART_KEY |
				   HA_END_SPACE_KEY)) == HA_NOSAME)
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	    {
	      tmp=prev_record_reads(join,found_ref);
	      records=1.0;
	    }
	    else
	    {
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	      if (!found_ref)
	      {					// We found a const key
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		if (table->quick_keys.is_set(key))
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		  records= (double) table->quick_rows[key];
		else
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		{
		  /* quick_range couldn't use key! */
		  records= (double) s->records/rec;
		}
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	      }
	      else
	      {
		if (!(records=keyinfo->rec_per_key[keyinfo->key_parts-1]))
		{				// Prefere longer keys
		  records=
		    ((double) s->records / (double) rec *
		     (1.0 +
		      ((double) (table->max_key_length-keyinfo->key_length) /
		       (double) table->max_key_length)));
		  if (records < 2.0)
		    records=2.0;		// Can't be as good as a unique
		}
	      }
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	      /* Limit the number of matched rows */
	      tmp= records;
	      set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
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	      if (table->used_keys.is_set(key))
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	      {
		/* we can use only index tree */
		uint keys_per_block= table->file->block_size/2/
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		  (keyinfo->key_length+table->file->ref_length)+1;
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		tmp=record_count*(tmp+keys_per_block-1)/keys_per_block;
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	      }
	      else
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		tmp=record_count*min(tmp,s->worst_seeks);
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	    }
	  }
	  else
	  {
	    /*
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	      Use as much key-parts as possible and a uniq key is better
	      than a not unique key
	      Set tmp to (previous record count) * (records / combination)
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	    */
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	    if ((found_part & 1) &&
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		(!(table->file->index_flags(key,0,0) & HA_ONLY_WHOLE_INDEX) ||
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		 found_part == PREV_BITS(uint,keyinfo->key_parts)))
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	    {
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	      max_key_part=max_part_bit(found_part);
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	      /*
		Check if quick_range could determinate how many rows we
		will match
	      */
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	      if (table->quick_keys.is_set(key) &&
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		  table->quick_key_parts[key] == max_key_part)
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		tmp=records= (double) table->quick_rows[key];
	      else
	      {
		/* Check if we have statistic about the distribution */
		if ((records=keyinfo->rec_per_key[max_key_part-1]))
		  tmp=records;
		else
		{
		  /*
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		    Assume that the first key part matches 1% of the file
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		    and that the hole key matches 10 (duplicates) or 1
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		    (unique) records.
		    Assume also that more key matches proportionally more
		    records
		    This gives the formula:
		    records= (x * (b-a) + a*c-b)/(c-1)
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		    b = records matched by whole key
		    a = records matched by first key part (10% of all records?)
		    c = number of key parts in key
		    x = used key parts (1 <= x <= c)
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		  */
		  double rec_per_key;
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                  rec_per_key= keyinfo->rec_per_key[keyinfo->key_parts-1] ?
		    (double) keyinfo->rec_per_key[keyinfo->key_parts-1] :
		    (double) s->records/rec+1;   
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		  if (!s->records)
		    tmp=0;
		  else if (rec_per_key/(double) s->records >= 0.01)
		    tmp=rec_per_key;
		  else
		  {
		    double a=s->records*0.01;
		    tmp=(max_key_part * (rec_per_key - a) +
			 a*keyinfo->key_parts - rec_per_key)/
		      (keyinfo->key_parts-1);
		    set_if_bigger(tmp,1.0);
		  }
		  records=(ulong) tmp;
		}
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		/*
		  If quick_select was used on a part of this key, we know
		  the maximum number of rows that the key can match.
		*/
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		if (table->quick_keys.is_set(key) &&
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		    table->quick_key_parts[key] <= max_key_part &&
		    records > (double) table->quick_rows[key])
		  tmp= records= (double) table->quick_rows[key];
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		else if (found_ref_or_null)
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		{
		  /* We need to do two key searches to find key */
		  tmp*= 2.0;
		  records*= 2.0;
		}
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	      }
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	      /* Limit the number of matched rows */
	      set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
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	      if (table->used_keys.is_set(key))
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	      {
		/* we can use only index tree */
		uint keys_per_block= table->file->block_size/2/
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		  (keyinfo->key_length+table->file->ref_length)+1;
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		tmp=record_count*(tmp+keys_per_block-1)/keys_per_block;
	      }
	      else
		tmp=record_count*min(tmp,s->worst_seeks);
	    }
	    else
	      tmp=best_time;			// Do nothing
	  }
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          } /* not ft_key */
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	  if (tmp < best_time - records/(double) TIME_FOR_COMPARE)
	  {
	    best_time=tmp + records/(double) TIME_FOR_COMPARE;
	    best=tmp;
	    best_records=records;
	    best_key=start_key;
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	    best_max_key_part=max_key_part;
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	  }
	}
	records=best_records;
      }
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      /*
	Don't test table scan if it can't be better.
	Prefer key lookup if we would use the same key for scanning.
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	Don't do a table scan on InnoDB tables, if we can read the used
	parts of the row from any of the used index.
	This is because table scans uses index and we would not win
	anything by using a table scan.
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      */
      if ((records >= s->found_records || best > s->read_time) &&
	  !(s->quick && best_key && s->quick->index == best_key->key &&
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	    best_max_key_part >= s->table->quick_key_parts[best_key->key]) &&
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	  !((s->table->file->table_flags() & HA_TABLE_SCAN_ON_INDEX) &&
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	    ! s->table->used_keys.is_clear_all() && best_key) &&
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	  !(s->table->force_index && best_key))
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      {						// Check full join
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        ha_rows rnd_records= s->found_records;
        /*
          If there is a restriction on the table, assume that 25% of the
          rows can be skipped on next part.
          This is to force tables that this table depends on before this
          table
        */
        if (found_constraint)
          rnd_records-= rnd_records/4;

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        /*
          Range optimizer never proposes a RANGE if it isn't better
          than FULL: so if RANGE is present, it's always preferred to FULL.
          Here we estimate its cost.
        */
        if (s->quick)
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        {
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          /*
            For each record we:
             - read record range through 'quick'
             - skip rows which does not satisfy WHERE constraints
           */
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          tmp= record_count *
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               (s->quick->read_time +
               (s->found_records - rnd_records)/(double) TIME_FOR_COMPARE);
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        }
        else
        {
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          /* Estimate cost of reading table. */
          tmp= s->table->file->scan_time();
          if (s->on_expr)                         // Can't use join cache
          {
            /*
              For each record we have to:
              - read the whole table record 
              - skip rows which does not satisfy join condition
            */
            tmp= record_count *
                 (tmp +     
                 (s->records - rnd_records)/(double) TIME_FOR_COMPARE);
          }
          else
          {
            /* We read the table as many times as join buffer becomes full. */
            tmp*= (1.0 + floor((double) cache_record_length(join,idx) *
                               record_count /
                               (double) thd->variables.join_buff_size));
            /* 
              We don't make full cartesian product between rows in the scanned
              table and existing records because we skip all rows from the
              scanned table, which does not satisfy join condition when 
              we read the table (see flush_cached_records for details). Here we
              take into account cost to read and skip these records.
            */
            tmp+= (s->records - rnd_records)/(double) TIME_FOR_COMPARE;
          }
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        }
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        /*
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          We estimate the cost of evaluating WHERE clause for found records
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          as record_count * rnd_records / TIME_FOR_COMPARE. This cost plus
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          tmp give us total cost of using TABLE SCAN
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        */
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	if (best == DBL_MAX ||
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	    (tmp  + record_count/(double) TIME_FOR_COMPARE*rnd_records <
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	     best + record_count/(double) TIME_FOR_COMPARE*records))
	{
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	  /*
	    If the table has a range (s->quick is set) make_join_select()
	    will ensure that this will be used
	  */
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	  best=tmp;
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	  records= rows2double(rnd_records);
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	  best_key=0;
	}
      }
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      join->positions[idx].records_read= records;
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      join->positions[idx].key=best_key;
      join->positions[idx].table= s;
      if (!best_key && idx == join->const_tables &&
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	  s->table == join->sort_by_table &&
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	  join->unit->select_limit_cnt >= records)
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	join->sort_by_table= (TABLE*) 1;	// Must use temporary table

     /*
	Go to the next level only if there hasn't been a better key on
	this level! This will cut down the search for a lot simple cases!
       */
      double current_record_count=record_count*records;
      double current_read_time=read_time+best;
      if (best_record_count > current_record_count ||
	  best_read_time > current_read_time ||
	  idx == join->const_tables && s->table == join->sort_by_table)
      {
	if (best_record_count >= current_record_count &&
	    best_read_time >= current_read_time &&
	    (!(s->key_dependent & rest_tables) || records < 2.0))
	{
	  best_record_count=current_record_count;
	  best_read_time=current_read_time;
	}
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	swap_variables(JOIN_TAB*, join->best_ref[idx], *pos);
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	find_best(join,rest_tables & ~real_table_bit,idx+1,
		  current_record_count,current_read_time);
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        if (thd->killed)
          return;
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	swap_variables(JOIN_TAB*, join->best_ref[idx], *pos);
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      }
      if (join->select_options & SELECT_STRAIGHT_JOIN)
	break;				// Don't test all combinations
    }
  }
}


/*
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  Find how much space the prevous read not const tables takes in cache
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*/

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static void calc_used_field_length(THD *thd, JOIN_TAB *join_tab)
{
  uint null_fields,blobs,fields,rec_length;
  null_fields=blobs=fields=rec_length=0;

  Field **f_ptr,*field;
  for (f_ptr=join_tab->table->field ; (field= *f_ptr) ; f_ptr++)
  {
    if (field->query_id == thd->query_id)
    {
      uint flags=field->flags;
      fields++;
      rec_length+=field->pack_length();
      if (flags & BLOB_FLAG)
	blobs++;
      if (!(flags & NOT_NULL_FLAG))
	null_fields++;
    }
  }
  if (null_fields)
    rec_length+=(join_tab->table->null_fields+7)/8;
  if (join_tab->table->maybe_null)
    rec_length+=sizeof(my_bool);
  if (blobs)
  {
    uint blob_length=(uint) (join_tab->table->file->mean_rec_length-
			     (join_tab->table->reclength- rec_length));
    rec_length+=(uint) max(4,blob_length);
  }
  join_tab->used_fields=fields;
  join_tab->used_fieldlength=rec_length;
  join_tab->used_blobs=blobs;
}


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static uint
cache_record_length(JOIN *join,uint idx)
{
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  uint length=0;
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  JOIN_TAB **pos,**end;
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  THD *thd=join->thd;
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  for (pos=join->best_ref+join->const_tables,end=join->best_ref+idx ;
       pos != end ;
       pos++)
  {
    JOIN_TAB *join_tab= *pos;
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    if (!join_tab->used_fieldlength)		/* Not calced yet */
      calc_used_field_length(thd, join_tab);
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    length+=join_tab->used_fieldlength;
  }
  return length;
}


static double
prev_record_reads(JOIN *join,table_map found_ref)
{
  double found=1.0;
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  found_ref&= ~OUTER_REF_TABLE_BIT;
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  for (POSITION *pos=join->positions ; found_ref ; pos++)
  {
    if (pos->table->table->map & found_ref)
    {
      found_ref&= ~pos->table->table->map;
      found*=pos->records_read;
    }
  }
  return found;
}


/*****************************************************************************
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  Set up join struct according to best position.
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*****************************************************************************/

static bool
get_best_combination(JOIN *join)
{
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  uint i,tablenr;
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  table_map used_tables;
  JOIN_TAB *join_tab,*j;
  KEYUSE *keyuse;
  uint table_count;
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  THD *thd=join->thd;
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  table_count=join->tables;
  if (!(join->join_tab=join_tab=
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	(JOIN_TAB*) thd->alloc(sizeof(JOIN_TAB)*table_count)))
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    return TRUE;

  join->full_join=0;

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  used_tables= OUTER_REF_TABLE_BIT;		// Outer row is already read
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  for (j=join_tab, tablenr=0 ; tablenr < table_count ; tablenr++,j++)
  {
    TABLE *form;
    *j= *join->best_positions[tablenr].table;
    form=join->table[tablenr]=j->table;
    used_tables|= form->map;
    form->reginfo.join_tab=j;
    if (!j->on_expr)
      form->reginfo.not_exists_optimize=0;	// Only with LEFT JOIN
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    if (j->type == JT_CONST)
      continue;					// Handled in make_join_stat..

    j->ref.key = -1;
    j->ref.key_parts=0;
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    if (j->type == JT_SYSTEM)
      continue;
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    if (j->keys.is_clear_all() || !(keyuse= join->best_positions[tablenr].key))
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    {
      j->type=JT_ALL;
      if (tablenr != join->const_tables)
	join->full_join=1;
    }
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    else if (create_ref_for_key(join, j, keyuse, used_tables))
      return TRUE;				// Something went wrong
  }
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  for (i=0 ; i < table_count ; i++)
    join->map2table[join->join_tab[i].table->tablenr]=join->join_tab+i;
  update_depend_map(join);
  return 0;
}
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static bool create_ref_for_key(JOIN *join, JOIN_TAB *j, KEYUSE *org_keyuse,
			       table_map used_tables)
{
  KEYUSE *keyuse=org_keyuse;
  bool ftkey=(keyuse->keypart == FT_KEYPART);
  THD  *thd= join->thd;
  uint keyparts,length,key;
  TABLE *table;
  KEY *keyinfo;
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  /*  Use best key from find_best */
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  table=j->table;
  key=keyuse->key;
  keyinfo=table->key_info+key;

  if (ftkey)
  {
    Item_func_match *ifm=(Item_func_match *)keyuse->val;

    length=0;
    keyparts=1;
    ifm->join_key=1;
  }
  else
  {
    keyparts=length=0;
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    uint found_part_ref_or_null= 0;
    /*
      Calculate length for the used key
      Stop if there is a missing key part or when we find second key_part
      with KEY_OPTIMIZE_REF_OR_NULL
    */
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    do
    {
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      if (!(~used_tables & keyuse->used_tables))
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      {
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	if (keyparts == keyuse->keypart &&
	    !(found_part_ref_or_null & keyuse->optimize))
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	{
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	  keyparts++;
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	  length+= keyinfo->key_part[keyuse->keypart].store_length;
	  found_part_ref_or_null|= keyuse->optimize;
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	}
      }
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      keyuse++;
    } while (keyuse->table == table && keyuse->key == key);
  } /* not ftkey */

  /* set up fieldref */
  keyinfo=table->key_info+key;
  j->ref.key_parts=keyparts;
  j->ref.key_length=length;
  j->ref.key=(int) key;
  if (!(j->ref.key_buff= (byte*) thd->calloc(ALIGN_SIZE(length)*2)) ||
      !(j->ref.key_copy= (store_key**) thd->alloc((sizeof(store_key*) *
						   (keyparts+1)))) ||
      !(j->ref.items=    (Item**) thd->alloc(sizeof(Item*)*keyparts)))
  {
    return TRUE;
  }
  j->ref.key_buff2=j->ref.key_buff+ALIGN_SIZE(length);
  j->ref.key_err=1;
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  j->ref.null_rejecting= 0;
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  keyuse=org_keyuse;

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  store_key **ref_key= j->ref.key_copy;
  byte *key_buff=j->ref.key_buff, *null_ref_key= 0;
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  bool keyuse_uses_no_tables= TRUE;
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  if (ftkey)
  {
    j->ref.items[0]=((Item_func*)(keyuse->val))->key_item();
    if (keyuse->used_tables)
      return TRUE; // not supported yet. SerG

    j->type=JT_FT;
  }
  else
  {
    uint i;
    for (i=0 ; i < keyparts ; keyuse++,i++)
    {
      while (keyuse->keypart != i ||
	     ((~used_tables) & keyuse->used_tables))
	keyuse++;				/* Skip other parts */

      uint maybe_null= test(keyinfo->key_part[i].null_bit);
      j->ref.items[i]=keyuse->val;		// Save for cond removal
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      if (keyuse->null_rejecting) 
        j->ref.null_rejecting |= 1 << i;
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      keyuse_uses_no_tables= keyuse_uses_no_tables && !keyuse->used_tables;
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      if (!keyuse->used_tables &&
	  !(join->select_options & SELECT_DESCRIBE))
      {					// Compare against constant
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	store_key_item tmp(thd, keyinfo->key_part[i].field,
                           (char*)key_buff + maybe_null,
                           maybe_null ?  (char*) key_buff : 0,
                           keyinfo->key_part[i].length, keyuse->val);
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	if (thd->is_fatal_error)
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	  return TRUE;
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	tmp.copy();
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      }
      else
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	*ref_key++= get_store_key(thd,
				  keyuse,join->const_table_map,
				  &keyinfo->key_part[i],
				  (char*) key_buff,maybe_null);
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      /*
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	Remeber if we are going to use REF_OR_NULL
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	But only if field _really_ can be null i.e. we force JT_REF
	instead of JT_REF_OR_NULL in case if field can't be null
      */
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      if ((keyuse->optimize & KEY_OPTIMIZE_REF_OR_NULL) && maybe_null)
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	null_ref_key= key_buff;
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      key_buff+=keyinfo->key_part[i].store_length;
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    }
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  } /* not ftkey */
  *ref_key=0;				// end_marker
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  if (j->type == JT_FT)
    return 0;
  if (j->type == JT_CONST)
    j->table->const_table= 1;
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  else if (((keyinfo->flags & (HA_NOSAME | HA_NULL_PART_KEY |
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			       HA_END_SPACE_KEY)) != HA_NOSAME) ||
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	   keyparts != keyinfo->key_parts || null_ref_key)
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  {
    /* Must read with repeat */
    j->type= null_ref_key ? JT_REF_OR_NULL : JT_REF;
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    j->ref.null_ref_key= null_ref_key;
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  }
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  else if (keyuse_uses_no_tables)
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  {
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    /*
      This happen if we are using a constant expression in the ON part
      of an LEFT JOIN.
      SELECT * FROM a LEFT JOIN b ON b.key=30
      Here we should not mark the table as a 'const' as a field may
      have a 'normal' value or a NULL value.
    */
    j->type=JT_CONST;
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  }
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  else
    j->type=JT_EQ_REF;
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  return 0;
}


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static store_key *
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get_store_key(THD *thd, KEYUSE *keyuse, table_map used_tables,
	      KEY_PART_INFO *key_part, char *key_buff, uint maybe_null)
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{
  if (!((~used_tables) & keyuse->used_tables))		// if const item
  {
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    return new store_key_const_item(thd,
				    key_part->field,
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				    key_buff + maybe_null,
				    maybe_null ? key_buff : 0,
				    key_part->length,
				    keyuse->val);
  }
  else if (keyuse->val->type() == Item::FIELD_ITEM)
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    return new store_key_field(thd,
			       key_part->field,
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			       key_buff + maybe_null,
			       maybe_null ? key_buff : 0,
			       key_part->length,
			       ((Item_field*) keyuse->val)->field,
			       keyuse->val->full_name());
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  return new store_key_item(thd,
			    key_part->field,
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			    key_buff + maybe_null,
			    maybe_null ? key_buff : 0,
			    key_part->length,
			    keyuse->val);
}

/*
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  This function is only called for const items on fields which are keys
  returns 1 if there was some conversion made when the field was stored.
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*/

bool
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store_val_in_field(Field *field, Item *item, enum_check_fields check_flag)
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{
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  bool error;
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  THD *thd=current_thd;
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  ha_rows cuted_fields=thd->cuted_fields;
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  /*
    we should restore old value of count_cuted_fields because
    store_val_in_field can be called from mysql_insert 
    with select_insert, which make count_cuted_fields= 1
   */
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  enum_check_fields old_count_cuted_fields= thd->count_cuted_fields;
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  thd->count_cuted_fields= check_flag;
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  error= item->save_in_field(field, 1);
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  thd->count_cuted_fields= old_count_cuted_fields;
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  return error || cuted_fields != thd->cuted_fields;
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}


static bool
make_simple_join(JOIN *join,TABLE *tmp_table)
{
  TABLE **tableptr;
  JOIN_TAB *join_tab;

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  if (!(tableptr=(TABLE**) join->thd->alloc(sizeof(TABLE*))) ||
      !(join_tab=(JOIN_TAB*) join->thd->alloc(sizeof(JOIN_TAB))))
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    return TRUE;
  join->join_tab=join_tab;
  join->table=tableptr; tableptr[0]=tmp_table;
  join->tables=1;
  join->const_tables=0;
  join->const_table_map=0;
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  join->tmp_table_param.field_count= join->tmp_table_param.sum_func_count=
    join->tmp_table_param.func_count=0;
  join->tmp_table_param.copy_field=join->tmp_table_param.copy_field_end=0;
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  join->first_record=join->sort_and_group=0;
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  join->send_records=(ha_rows) 0;
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  join->group=0;
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  join->row_limit=join->unit->select_limit_cnt;
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  join->do_send_rows = (join->row_limit) ? 1 : 0;
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  join_tab->cache.buff=0;			/* No caching */
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  join_tab->table=tmp_table;
  join_tab->select=0;
  join_tab->select_cond=0;
  join_tab->quick=0;
  join_tab->type= JT_ALL;			/* Map through all records */
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  join_tab->keys.init();
  join_tab->keys.set_all();                     /* test everything in quick */
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  join_tab->info=0;
  join_tab->on_expr=0;
  join_tab->ref.key = -1;
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  join_tab->not_used_in_distinct=0;
  join_tab->read_first_record= join_init_read_record;
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  join_tab->join=join;
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  bzero((char*) &join_tab->read_record,sizeof(join_tab->read_record));
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  tmp_table->status=0;
  tmp_table->null_row=0;
  return FALSE;
}


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inline void add_cond_and_fix(Item **e1, Item *e2)
{
  if (*e1)
  {
    Item *res;
    if ((res= new Item_cond_and(*e1, e2)))
    {
      *e1= res;
      res->quick_fix_field();
    }
  }
  else
    *e1= e2;
}


/*
  Add to join_tab->select_cond[i] "table.field IS NOT NULL" conditions we've
  inferred from ref/eq_ref access performed.

  SYNOPSIS
    add_not_null_conds()
      join  Join to process

  NOTES
    This function is a part of "Early NULL-values filtering for ref access"
    optimization.

    Example of this optimization:
      For query SELECT * FROM t1,t2 WHERE t2.key=t1.field
      and plan " any-access(t1), ref(t2.key=t1.field) "
      add "t1.field IS NOT NULL" to t1's table condition.
    Description of the optimization:
    
      We look through equalities choosen to perform ref/eq_ref access,
      pick equalities that have form "tbl.part_of_key = othertbl.field"
      (where othertbl is a non-const table and othertbl.field may be NULL)
      and add them to conditions on correspoding tables (othertbl in this
      example).
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      Exception from that is the case when referred_tab->join != join.
      I.e. don't add NOT NULL constraints from any embedded subquery.
      Consider this query:
      SELECT A.f2 FROM t1 LEFT JOIN t2 A ON A.f2 = f1
      WHERE A.f3=(SELECT MIN(f3) FROM  t2 C WHERE A.f4 = C.f4) OR A.f3 IS NULL;
      Here condition A.f3 IS NOT NULL is going to be added to the WHERE
      condition of the embedding query.
      Another example:
      SELECT * FROM t10, t11 WHERE (t10.a < 10 OR t10.a IS NULL)
      AND t11.b <=> t10.b AND (t11.a = (SELECT MAX(a) FROM t12
      WHERE t12.b = t10.a ));
      Here condition t10.a IS NOT NULL is going to be added.
      In both cases addition of NOT NULL condition will erroneously reject
      some rows of the result set.
      referred_tab->join != join constraint would disallow such additions.

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      This optimization doesn't affect the choices that ref, range, or join
      optimizer make. This was intentional because this was added after 4.1
      was GA.
      
    Implementation overview
      1. update_ref_and_keys() accumulates info about null-rejecting
         predicates in in KEY_FIELD::null_rejecting
      1.1 add_key_part saves these to KEYUSE.
      2. create_ref_for_key copies them to TABLE_REF.
      3. add_not_null_conds adds "x IS NOT NULL" to join_tab->select_cond of
         appropiate JOIN_TAB members.
*/

static void add_not_null_conds(JOIN *join)
{
  DBUG_ENTER("add_not_null_conds");
  for (uint i=join->const_tables ; i < join->tables ; i++)
  {
    JOIN_TAB *tab=join->join_tab+i;
    if ((tab->type == JT_REF || tab->type == JT_REF_OR_NULL) &&
         !tab->table->maybe_null)
    {
      for (uint keypart= 0; keypart < tab->ref.key_parts; keypart++)
      {
        if (tab->ref.null_rejecting & (1 << keypart))
        {
          Item *item= tab->ref.items[keypart];
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          Item *notnull;
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          DBUG_ASSERT(item->type() == Item::FIELD_ITEM);
          Item_field *not_null_item= (Item_field*)item;
          JOIN_TAB *referred_tab= not_null_item->field->table->reginfo.join_tab;
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          /*
            For UPDATE queries such as:
            UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1);
            not_null_item is the t1.f1, but it's referred_tab is 0.
          */
          if (!referred_tab || referred_tab->join != join)
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            continue;
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          if (!(notnull= new Item_func_isnotnull(not_null_item)))
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            DBUG_VOID_RETURN;
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          /*
            We need to do full fix_fields() call here in order to have correct
            notnull->const_item(). This is needed e.g. by test_quick_select 
            when it is called from make_join_select after this function is 
            called.
          */
          if (notnull->fix_fields(join->thd, join->tables_list, &notnull))
            DBUG_VOID_RETURN;
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          DBUG_EXECUTE("where",print_where(notnull,
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                                           referred_tab->table->table_name););
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          add_cond_and_fix(&referred_tab->select_cond, notnull);
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        }
      }
    }
  }
  DBUG_VOID_RETURN;
}

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static bool
make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
{
  DBUG_ENTER("make_join_select");
  if (select)
  {
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    add_not_null_conds(join);
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    table_map used_tables;
    if (join->tables > 1)
      cond->update_used_tables();		// Tablenr may have changed
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    if (join->const_tables == join->tables &&
	join->thd->lex->current_select->master_unit() ==
	&join->thd->lex->unit)		// not upper level SELECT
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      join->const_table_map|=RAND_TABLE_BIT;
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    {						// Check const tables
      COND *const_cond=
	make_cond_for_table(cond,join->const_table_map,(table_map) 0);
      DBUG_EXECUTE("where",print_where(const_cond,"constants"););
      if (const_cond && !const_cond->val_int())
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      {
	DBUG_PRINT("info",("Found impossible WHERE condition"));
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	DBUG_RETURN(1);				// Impossible const condition
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      }
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    }
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    used_tables=((select->const_tables=join->const_table_map) |
		 OUTER_REF_TABLE_BIT | RAND_TABLE_BIT);
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    for (uint i=join->const_tables ; i < join->tables ; i++)
    {
      JOIN_TAB *tab=join->join_tab+i;
      table_map current_map= tab->table->map;
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      /*
	Following force including random expression in last table condition.
	It solve problem with select like SELECT * FROM t1 WHERE rand() > 0.5
      */
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      if (i == join->tables-1)
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	current_map|= OUTER_REF_TABLE_BIT | RAND_TABLE_BIT;
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      bool use_quick_range=0;
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      used_tables|=current_map;
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      if (tab->type == JT_REF && tab->quick &&
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	  (uint) tab->ref.key == tab->quick->index &&
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	  tab->ref.key_length < tab->quick->max_used_key_length)
      {
	/* Range uses longer key;  Use this instead of ref on key */
	tab->type=JT_ALL;
	use_quick_range=1;
	tab->use_quick=1;
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        tab->ref.key= -1;
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	tab->ref.key_parts=0;		// Don't use ref key.
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	join->best_positions[i].records_read= rows2double(tab->quick->records);
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      }

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      COND *tmp=make_cond_for_table(cond,used_tables,current_map);
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      if (!tmp && tab->quick)
      {						// Outer join
	/*
	  Hack to handle the case where we only refer to a table
	  in the ON part of an OUTER JOIN.
	*/
	tmp=new Item_int((longlong) 1,1);	// Always true
      }
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      if (tmp)
      {
	SQL_SELECT *sel=tab->select=(SQL_SELECT*)
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	  join->thd->memdup((gptr) select, sizeof(SQL_SELECT));
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	if (!sel)
	  DBUG_RETURN(1);			// End of memory
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        add_cond_and_fix(&tab->select_cond, tmp);
        sel->cond= tab->select_cond;
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	sel->head=tab->table;
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	DBUG_EXECUTE("where",print_where(tmp,tab->table->table_name););
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	if (tab->quick)
	{
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	  /* Use quick key read if it's a constant and it's not used
	     with key reading */
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	  if (tab->needed_reg.is_clear_all() && tab->type != JT_EQ_REF
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	      && tab->type != JT_FT && (tab->type != JT_REF ||
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	       (uint) tab->ref.key == tab->quick->index))
	  {
	    sel->quick=tab->quick;		// Use value from get_quick_...
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	    sel->quick_keys.clear_all();
	    sel->needed_reg.clear_all();
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	  }
	  else
	  {
	    delete tab->quick;
	  }
	  tab->quick=0;
	}
	uint ref_key=(uint) sel->head->reginfo.join_tab->ref.key+1;
	if (i == join->const_tables && ref_key)
	{
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	  if (!tab->const_keys.is_clear_all() &&
              tab->table->reginfo.impossible_range)
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	    DBUG_RETURN(1);
	}
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	else if (tab->type == JT_ALL && ! use_quick_range)
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	{
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	  if (!tab->const_keys.is_clear_all() &&
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	      tab->table->reginfo.impossible_range)
	    DBUG_RETURN(1);				// Impossible range
	  /*
	    We plan to scan all rows.
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	    Check again if we should use an index.
	    We could have used an column from a previous table in
	    the index if we are using limit and this is the first table
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	  */

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	  if ((!tab->keys.is_subset(tab->const_keys) && i > 0) ||
	      (!tab->const_keys.is_clear_all() && i == join->const_tables &&
	       join->unit->select_limit_cnt <
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	       join->best_positions[i].records_read &&
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	       !(join->select_options & OPTION_FOUND_ROWS)))
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	  {
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	    /* Join with outer join condition */
	    COND *orig_cond=sel->cond;
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	    sel->cond= and_conds(sel->cond, tab->on_expr);
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	    /*
              We can't call sel->cond->fix_fields,
              as it will break tab->on_expr if it's AND condition
              (fix_fields currently removes extra AND/OR levels).
              Yet attributes of the just built condition are not needed.
              Thus we call sel->cond->quick_fix_field for safety.
	    */
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	    if (sel->cond && !sel->cond->fixed)
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	      sel->cond->quick_fix_field();

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	    if (sel->test_quick_select(join->thd, tab->keys,
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				       used_tables & ~ current_map,
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				       (join->select_options &
					OPTION_FOUND_ROWS ?
					HA_POS_ERROR :
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					join->unit->select_limit_cnt), 0) < 0)
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            {
	      /*
		Before reporting "Impossible WHERE" for the whole query
		we have to check isn't it only "impossible ON" instead
	      */
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              sel->cond=orig_cond;
              if (!tab->on_expr ||
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                  sel->test_quick_select(join->thd, tab->keys,
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                                         used_tables & ~ current_map,
                                         (join->select_options &
                                          OPTION_FOUND_ROWS ?
                                          HA_POS_ERROR :
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                                          join->unit->select_limit_cnt),0) < 0)
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		DBUG_RETURN(1);			// Impossible WHERE
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            }
            else
	      sel->cond=orig_cond;

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	    /* Fix for EXPLAIN */
	    if (sel->quick)
	      join->best_positions[i].records_read= sel->quick->records;
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	  }
	  else
	  {
	    sel->needed_reg=tab->needed_reg;
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	    sel->quick_keys.clear_all();
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	  }
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	  if (!sel->quick_keys.is_subset(tab->checked_keys) ||
              !sel->needed_reg.is_subset(tab->checked_keys))
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	  {
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	    tab->keys=sel->quick_keys;
            tab->keys.merge(sel->needed_reg);
	    tab->use_quick= (!sel->needed_reg.is_clear_all() &&
			     (select->quick_keys.is_clear_all() ||
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			      (select->quick &&
			       (select->quick->records >= 100L)))) ?
	      2 : 1;
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	    sel->read_tables= used_tables & ~current_map;
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	  }
	  if (i != join->const_tables && tab->use_quick != 2)
	  {					/* Read with cache */
	    if ((tmp=make_cond_for_table(cond,
					 join->const_table_map |
					 current_map,
					 current_map)))
	    {
	      DBUG_EXECUTE("where",print_where(tmp,"cache"););
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	      tab->cache.select=(SQL_SELECT*)
		join->thd->memdup((gptr) sel, sizeof(SQL_SELECT));
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	      tab->cache.select->cond=tmp;
	      tab->cache.select->read_tables=join->const_table_map;
	    }
	  }
	}
      }
    }
  }
  DBUG_RETURN(0);
}


static void
3882
make_join_readinfo(JOIN *join, uint options)
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{
  uint i;
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  bool statistics= test(!(join->select_options & SELECT_DESCRIBE));
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  bool ordered_set= 0;
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  DBUG_ENTER("make_join_readinfo");

  for (i=join->const_tables ; i < join->tables ; i++)
  {
    JOIN_TAB *tab=join->join_tab+i;
    TABLE *table=tab->table;
    tab->read_record.table= table;
    tab->read_record.file=table->file;
    tab->next_select=sub_select;		/* normal select */
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    /*
      Determine if the set is already ordered for ORDER BY, so it can 
      disable join cache because it will change the ordering of the results.
      Code handles sort table that is at any location (not only first after 
      the const tables) despite the fact that it's currently prohibited.
    */
    if (!ordered_set && 
        (table == join->sort_by_table &&
         (!join->order || join->skip_sort_order ||
          test_if_skip_sort_order(tab, join->order, join->select_limit,
                                  1))
        ) ||
        (join->sort_by_table == (TABLE *) 1 && i != join->const_tables))
      ordered_set= 1;

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    switch (tab->type) {
    case JT_SYSTEM:				// Only happens with left join
      table->status=STATUS_NO_RECORD;
      tab->read_first_record= join_read_system;
      tab->read_record.read_record= join_no_more_records;
      break;
    case JT_CONST:				// Only happens with left join
      table->status=STATUS_NO_RECORD;
      tab->read_first_record= join_read_const;
      tab->read_record.read_record= join_no_more_records;
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      if (table->used_keys.is_set(tab->ref.key) &&
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          !table->no_keyread)
      {
        table->key_read=1;
        table->file->extra(HA_EXTRA_KEYREAD);
      }
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      break;
    case JT_EQ_REF:
      table->status=STATUS_NO_RECORD;
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      if (tab->select)
      {
	delete tab->select->quick;
	tab->select->quick=0;
      }
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      delete tab->quick;
      tab->quick=0;
      tab->read_first_record= join_read_key;
      tab->read_record.read_record= join_no_more_records;
3940
      if (table->used_keys.is_set(tab->ref.key) &&
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	  !table->no_keyread)
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      {
	table->key_read=1;
	table->file->extra(HA_EXTRA_KEYREAD);
      }
      break;
3947
    case JT_REF_OR_NULL:
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    case JT_REF:
      table->status=STATUS_NO_RECORD;
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      if (tab->select)
      {
	delete tab->select->quick;
	tab->select->quick=0;
      }
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      delete tab->quick;
      tab->quick=0;
3957
      if (table->used_keys.is_set(tab->ref.key) &&
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	  !table->no_keyread)
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      {
	table->key_read=1;
	table->file->extra(HA_EXTRA_KEYREAD);
      }
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      if (tab->type == JT_REF)
      {
	tab->read_first_record= join_read_always_key;
	tab->read_record.read_record= join_read_next_same;
      }
      else
      {
	tab->read_first_record= join_read_always_key_or_null;
	tab->read_record.read_record= join_read_next_same_or_null;
      }
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      break;
    case JT_FT:
      table->status=STATUS_NO_RECORD;
      tab->read_first_record= join_ft_read_first;
      tab->read_record.read_record= join_ft_read_next;
      break;
    case JT_ALL:
      /*
3981
	If previous table use cache
3982
        If the incoming data set is already sorted don't use cache.
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      */
      table->status=STATUS_NO_RECORD;
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      if (i != join->const_tables && !(options & SELECT_NO_JOIN_CACHE) &&
3986
	  tab->use_quick != 2 && !tab->on_expr && !ordered_set)
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      {
	if ((options & SELECT_DESCRIBE) ||
	    !join_init_cache(join->thd,join->join_tab+join->const_tables,
			     i-join->const_tables))
	{
	  tab[-1].next_select=sub_select_cache; /* Patch previous */
	}
      }
      /* These init changes read_record */
      if (tab->use_quick == 2)
3997
      {
3998
	join->thd->server_status|=SERVER_QUERY_NO_GOOD_INDEX_USED;
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	tab->read_first_record= join_init_quick_read_record;
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	if (statistics)
	  statistic_increment(select_range_check_count, &LOCK_status);
4002
      }
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      else
      {
	tab->read_first_record= join_init_read_record;
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	if (i == join->const_tables)
	{
	  if (tab->select && tab->select->quick)
	  {
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	    if (statistics)
	      statistic_increment(select_range_count, &LOCK_status);
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	  }
	  else
	  {
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	    join->thd->server_status|=SERVER_QUERY_NO_INDEX_USED;
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	    if (statistics)
	      statistic_increment(select_scan_count, &LOCK_status);
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	  }
	}
	else
	{
	  if (tab->select && tab->select->quick)
	  {
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	    if (statistics)
	      statistic_increment(select_full_range_join_count, &LOCK_status);
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	  }
	  else
	  {
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	    join->thd->server_status|=SERVER_QUERY_NO_INDEX_USED;
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	    if (statistics)
	      statistic_increment(select_full_join_count, &LOCK_status);
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	  }
	}
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	if (!table->no_keyread)
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	{
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	  if (tab->select && tab->select->quick &&
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	      table->used_keys.is_set(tab->select->quick->index))
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	  {
	    table->key_read=1;
	    table->file->extra(HA_EXTRA_KEYREAD);
	  }
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	  else if (!table->used_keys.is_clear_all() &&
		   !(tab->select && tab->select->quick))
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	  {					// Only read index tree
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	    tab->index=find_shortest_key(table, & table->used_keys);
4046
	    tab->read_first_record= join_read_first;
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	    tab->type=JT_NEXT;		// Read with index_first / index_next
	  }
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	}
      }
      break;
    default:
      DBUG_PRINT("error",("Table type %d found",tab->type)); /* purecov: deadcode */
      break;					/* purecov: deadcode */
    case JT_UNKNOWN:
    case JT_MAYBE_REF:
      abort();					/* purecov: deadcode */
    }
  }
  join->join_tab[join->tables-1].next_select=0; /* Set by do_select */
  DBUG_VOID_RETURN;
}


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/*
  Give error if we some tables are done with a full join

  SYNOPSIS
    error_if_full_join()
    join		Join condition

  USAGE
   This is used by multi_table_update and multi_table_delete when running
   in safe mode

 RETURN VALUES
   0	ok
   1	Error (full join used)
*/

bool error_if_full_join(JOIN *join)
{
  for (JOIN_TAB *tab=join->join_tab, *end=join->join_tab+join->tables;
       tab < end;
       tab++)
  {
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    if (tab->type == JT_ALL && (!tab->select || !tab->select->quick))
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    {
      my_error(ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE,MYF(0));
      return(1);
    }
  }
  return(0);
}


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/*
  cleanup JOIN_TAB

  SYNOPSIS
    JOIN_TAB::cleanup()
*/

void JOIN_TAB::cleanup()
{
  delete select;
  select= 0;
  delete quick;
  quick= 0;
  x_free(cache.buff);
  cache.buff= 0;
  if (table)
  {
    if (table->key_read)
    {
      table->key_read= 0;
      table->file->extra(HA_EXTRA_NO_KEYREAD);
    }
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    table->file->ha_index_or_rnd_end();
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    /*
      We need to reset this for next select
      (Tested in part_of_refkey)
    */
    table->reginfo.join_tab= 0;
  }
  end_read_record(&read_record);
}


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/*
  Free resources of given join

  SYNOPSIS
    JOIN::join_free()
    fill - true if we should free all resources, call with full==1 should be
           last, before it this function can be called with full==0

  NOTE: with subquery this function definitely will be called several times,
    but even for simple query it can be called several times.
*/
void
JOIN::join_free(bool full)
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{
  JOIN_TAB *tab,*end;
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  DBUG_ENTER("JOIN::join_free");
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4147
  full= full || (!select_lex->uncacheable &&
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                 !thd->lex->subqueries &&
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                 !thd->lex->describe); // do not cleanup too early on EXPLAIN
4150

4151
  if (table)
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  {
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    /*
      Only a sorted table may be cached.  This sorted table is always the
      first non const table in join->table
    */
4157
    if (tables > const_tables) // Test for not-const tables
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    {
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      free_io_cache(table[const_tables]);
      filesort_free_buffers(table[const_tables]);
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    }
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    for (SELECT_LEX_UNIT *unit= select_lex->first_inner_unit(); unit;
         unit= unit->next_unit())
    {
      JOIN *join;
      for (SELECT_LEX *sl= unit->first_select_in_union(); sl;
           sl= sl->next_select())
        if ((join= sl->join))
          join->join_free(full);
    }

    if (full)
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    {
      for (tab= join_tab, end= tab+tables; tab != end; tab++)
	tab->cleanup();
      table= 0;
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      tables= 0;
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    }
    else
4181
    {
4182
      for (tab= join_tab, end= tab+tables; tab != end; tab++)
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      {
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	if (tab->table)
	    tab->table->file->ha_index_or_rnd_end();
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      }
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    }
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  }
4189

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  /*
    We are not using tables anymore
    Unlock all tables. We may be in an INSERT .... SELECT statement.
  */
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  if (full && lock && thd->lock && !(select_options & SELECT_NO_UNLOCK) &&
4195
      !select_lex->subquery_in_having)
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  {
4197 4198 4199 4200 4201 4202 4203
    // TODO: unlock tables even if the join isn't top level select in the tree
    if (select_lex == (thd->lex->unit.fake_select_lex ?
                       thd->lex->unit.fake_select_lex : &thd->lex->select_lex))
    {
      mysql_unlock_read_tables(thd, lock);        // Don't free join->lock
      lock=0;
    }
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  }
4205

4206 4207
  if (full)
  {
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    group_fields.delete_elements();
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    /*
      We can't call delete_elements() on copy_funcs as this will cause
      problems in free_elements() as some of the elements are then deleted.
    */
    tmp_table_param.copy_funcs.empty();
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    /*
      If we have tmp_join and 'this' JOIN is not tmp_join and
      tmp_table_param.copy_field's  of them are equal then we have to remove
      pointer to  tmp_table_param.copy_field from tmp_join, because it qill
      be removed in tmp_table_param.cleanup().
    */
    if (tmp_join &&
        tmp_join != this &&
        tmp_join->tmp_table_param.copy_field ==
        tmp_table_param.copy_field)
    {
      tmp_join->tmp_table_param.copy_field=
        tmp_join->tmp_table_param.save_copy_field= 0;
    }
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    tmp_table_param.cleanup();
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  }
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  DBUG_VOID_RETURN;
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}


/*****************************************************************************
4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247
  Remove the following expressions from ORDER BY and GROUP BY:
  Constant expressions
  Expression that only uses tables that are of type EQ_REF and the reference
  is in the ORDER list or if all refereed tables are of the above type.

  In the following, the X field can be removed:
  SELECT * FROM t1,t2 WHERE t1.a=t2.a ORDER BY t1.a,t2.X
  SELECT * FROM t1,t2,t3 WHERE t1.a=t2.a AND t2.b=t3.b ORDER BY t1.a,t3.X

  These can't be optimized:
  SELECT * FROM t1,t2 WHERE t1.a=t2.a ORDER BY t2.X,t1.a
  SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b=t2.b ORDER BY t1.a,t2.c
  SELECT * FROM t1,t2 WHERE t1.a=t2.a ORDER BY t2.b,t1.a
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*****************************************************************************/

static bool
eq_ref_table(JOIN *join, ORDER *start_order, JOIN_TAB *tab)
{
  if (tab->cached_eq_ref_table)			// If cached
    return tab->eq_ref_table;
  tab->cached_eq_ref_table=1;
  if (tab->type == JT_CONST)			// We can skip const tables
    return (tab->eq_ref_table=1);		/* purecov: inspected */
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  if (tab->type != JT_EQ_REF || tab->table->maybe_null)
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    return (tab->eq_ref_table=0);		// We must use this
  Item **ref_item=tab->ref.items;
  Item **end=ref_item+tab->ref.key_parts;
  uint found=0;
  table_map map=tab->table->map;

  for (; ref_item != end ; ref_item++)
  {
    if (! (*ref_item)->const_item())
    {						// Not a const ref
      ORDER *order;
      for (order=start_order ; order ; order=order->next)
      {
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	if ((*ref_item)->eq(order->item[0],0))
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	  break;
      }
      if (order)
      {
	found++;
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	DBUG_ASSERT(!(order->used & map));
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	order->used|=map;
	continue;				// Used in ORDER BY
      }
      if (!only_eq_ref_tables(join,start_order, (*ref_item)->used_tables()))
	return (tab->eq_ref_table=0);
    }
  }
  /* Check that there was no reference to table before sort order */
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  for (; found && start_order ; start_order=start_order->next)
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  {
    if (start_order->used & map)
    {
      found--;
      continue;
    }
    if (start_order->depend_map & map)
      return (tab->eq_ref_table=0);
  }
  return tab->eq_ref_table=1;
}


static bool
only_eq_ref_tables(JOIN *join,ORDER *order,table_map tables)
{
  if (specialflag &  SPECIAL_SAFE_MODE)
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    return 0;			// skip this optimize /* purecov: inspected */
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  for (JOIN_TAB **tab=join->map2table ; tables ; tab++, tables>>=1)
  {
    if (tables & 1 && !eq_ref_table(join, order, *tab))
      return 0;
  }
  return 1;
}


/* Update the dependency map for the tables */

static void update_depend_map(JOIN *join)
{
  JOIN_TAB *join_tab=join->join_tab, *end=join_tab+join->tables;

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  for (; join_tab != end ; join_tab++)
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  {
    TABLE_REF *ref= &join_tab->ref;
    table_map depend_map=0;
    Item **item=ref->items;
    uint i;
    for (i=0 ; i < ref->key_parts ; i++,item++)
      depend_map|=(*item)->used_tables();
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    ref->depend_map=depend_map & ~OUTER_REF_TABLE_BIT;
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    depend_map&= ~OUTER_REF_TABLE_BIT;
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    for (JOIN_TAB **tab=join->map2table;
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	 depend_map ;
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	 tab++,depend_map>>=1 )
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    {
      if (depend_map & 1)
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	ref->depend_map|=(*tab)->ref.depend_map;
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    }
  }
}


/* Update the dependency map for the sort order */

static void update_depend_map(JOIN *join, ORDER *order)
{
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  for (; order ; order=order->next)
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  {
    table_map depend_map;
    order->item[0]->update_used_tables();
    order->depend_map=depend_map=order->item[0]->used_tables();
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    // Not item_sum(), RAND() and no reference to table outside of sub select
    if (!(order->depend_map & (OUTER_REF_TABLE_BIT | RAND_TABLE_BIT)))
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    {
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      for (JOIN_TAB **tab=join->map2table;
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	   depend_map ;
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	   tab++, depend_map>>=1)
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      {
	if (depend_map & 1)
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	  order->depend_map|=(*tab)->ref.depend_map;
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      }
    }
  }
}


/*
4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384
  Remove all constants and check if ORDER only contains simple expressions

  SYNOPSIS
   remove_const()
   join			Join handler
   first_order		List of SORT or GROUP order
   cond			WHERE statement
   change_list		Set to 1 if we should remove things from list
			If this is not set, then only simple_order is
                        calculated   
   simple_order		Set to 1 if we are only using simple expressions

  RETURN
    Returns new sort order

    simple_order is set to 1 if sort_order only uses fields from head table
    and the head table is not a LEFT JOIN table

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*/

static ORDER *
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remove_const(JOIN *join,ORDER *first_order, COND *cond,
             bool change_list, bool *simple_order)
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{
  if (join->tables == join->const_tables)
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    return change_list ? 0 : first_order;		// No need to sort

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  ORDER *order,**prev_ptr;
  table_map first_table= join->join_tab[join->const_tables].table->map;
  table_map not_const_tables= ~join->const_table_map;
  table_map ref;
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  DBUG_ENTER("remove_const");

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  prev_ptr= &first_order;
  *simple_order= join->join_tab[join->const_tables].on_expr ? 0 : 1;

  /* NOTE: A variable of not_const_tables ^ first_table; breaks gcc 2.7 */

  update_depend_map(join, first_order);
  for (order=first_order; order ; order=order->next)
  {
    table_map order_tables=order->item[0]->used_tables();
    if (order->item[0]->with_sum_func)
      *simple_order=0;				// Must do a temp table to sort
    else if (!(order_tables & not_const_tables))
    {
      DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
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      continue;					// skip const item
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    }
    else
    {
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      if (order_tables & (RAND_TABLE_BIT | OUTER_REF_TABLE_BIT))
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	*simple_order=0;
      else
      {
	Item *comp_item=0;
	if (cond && const_expression_in_where(cond,order->item[0], &comp_item))
	{
	  DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
	  continue;
	}
	if ((ref=order_tables & (not_const_tables ^ first_table)))
	{
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	  if (!(order_tables & first_table) &&
              only_eq_ref_tables(join,first_order, ref))
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	  {
	    DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
	    continue;
	  }
	  *simple_order=0;			// Must do a temp table to sort
	}
      }
    }
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    if (change_list)
      *prev_ptr= order;				// use this entry
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    prev_ptr= &order->next;
  }
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  if (change_list)
    *prev_ptr=0;
  if (prev_ptr == &first_order)			// Nothing to sort/group
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    *simple_order=1;
  DBUG_PRINT("exit",("simple_order: %d",(int) *simple_order));
  DBUG_RETURN(first_order);
}

4452

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static int
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return_zero_rows(JOIN *join, select_result *result,TABLE_LIST *tables,
		 List<Item> &fields, bool send_row, uint select_options,
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		 const char *info, Item *having, Procedure *procedure,
		 SELECT_LEX_UNIT *unit)
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{
  DBUG_ENTER("return_zero_rows");

  if (select_options & SELECT_DESCRIBE)
4462
  {
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    select_describe(join, FALSE, FALSE, FALSE, info);
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    DBUG_RETURN(0);
  }
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  join->join_free(0);

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  if (send_row)
  {
    for (TABLE_LIST *table=tables; table ; table=table->next)
      mark_as_null_row(table->table);		// All fields are NULL
4473
    if (having && having->val_int() == 0)
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      send_row=0;
  }
4476
  if (!(result->send_fields(fields,1)))
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  {
    if (send_row)
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    {
      List_iterator_fast<Item> it(fields);
      Item *item;
      while ((item= it++))
	item->no_rows_in_result();
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      result->send_data(fields);
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    }
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    result->send_eof();				// Should be safe
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  }
4488 4489
  /* Update results for FOUND_ROWS */
  join->thd->limit_found_rows= join->thd->examined_row_count= 0;
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  DBUG_RETURN(0);
}

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/*
  used only in JOIN::clear
*/
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static void clear_tables(JOIN *join)
{
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  /* 
    must clear only the non-const tables, as const tables
    are not re-calculated.
  */
  for (uint i=join->const_tables ; i < join->tables ; i++)
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    mark_as_null_row(join->table[i]);		// All fields are NULL
}

/*****************************************************************************
4507 4508 4509 4510 4511 4512
  Make som simple condition optimization:
  If there is a test 'field = const' change all refs to 'field' to 'const'
  Remove all dummy tests 'item = item', 'const op const'.
  Remove all 'item is NULL', when item can never be null!
  item->marker should be 0 for all items on entry
  Return in cond_value FALSE if condition is impossible (1 = 2)
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*****************************************************************************/

class COND_CMP :public ilink {
public:
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  static void *operator new(size_t size) {return (void*) sql_alloc((uint) size); }
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  static void operator delete(void *ptr __attribute__((unused)),
			      size_t size __attribute__((unused))) {} /*lint -e715 */

  Item *and_level;
  Item_func *cmp_func;
  COND_CMP(Item *a,Item_func *b) :and_level(a),cmp_func(b) {}
};

#ifdef __GNUC__
template class I_List<COND_CMP>;
template class I_List_iterator<COND_CMP>;
template class List<Item_func_match>;
template class List_iterator<Item_func_match>;
#endif

/*
4534 4535
  change field = field to field = const for each found field = const in the
  and_level
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*/

static void
4539 4540 4541
change_cond_ref_to_const(THD *thd, I_List<COND_CMP> *save_list,
                         Item *and_father, Item *cond,
                         Item *field, Item *value)
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{
  if (cond->type() == Item::COND_ITEM)
  {
    bool and_level= ((Item_cond*) cond)->functype() ==
      Item_func::COND_AND_FUNC;
    List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
    Item *item;
    while ((item=li++))
4550
      change_cond_ref_to_const(thd, save_list,and_level ? cond : item, item,
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			       field, value);
    return;
  }
  if (cond->eq_cmp_result() == Item::COND_OK)
    return;					// Not a boolean function

  Item_bool_func2 *func=  (Item_bool_func2*) cond;
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  Item **args= func->arguments();
  Item *left_item=  args[0];
  Item *right_item= args[1];
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  Item_func::Functype functype=  func->functype();

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  if (right_item->eq(field,0) && left_item != value &&
      (left_item->result_type() != STRING_RESULT ||
       value->result_type() != STRING_RESULT ||
       left_item->collation.collation == value->collation.collation))
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  {
    Item *tmp=value->new_item();
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    tmp->collation.set(right_item->collation);
    
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    if (tmp)
    {
4573
      thd->change_item_tree(args + 1, tmp);
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      func->update_used_tables();
      if ((functype == Item_func::EQ_FUNC || functype == Item_func::EQUAL_FUNC)
	  && and_father != cond && !left_item->const_item())
      {
	cond->marker=1;
	COND_CMP *tmp2;
	if ((tmp2=new COND_CMP(and_father,func)))
	  save_list->push_back(tmp2);
      }
4583
      func->set_cmp_func();
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    }
  }
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  else if (left_item->eq(field,0) && right_item != value &&
           (right_item->result_type() != STRING_RESULT ||
            value->result_type() != STRING_RESULT ||
            right_item->collation.collation == value->collation.collation))
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  {
    Item *tmp=value->new_item();
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    tmp->collation.set(left_item->collation);
    
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    if (tmp)
    {
4596 4597
      thd->change_item_tree(args, tmp);
      value= tmp;
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      func->update_used_tables();
      if ((functype == Item_func::EQ_FUNC || functype == Item_func::EQUAL_FUNC)
	  && and_father != cond && !right_item->const_item())
      {
4602
        args[0]= args[1];                       // For easy check
4603
        thd->change_item_tree(args + 1, value);
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	cond->marker=1;
	COND_CMP *tmp2;
	if ((tmp2=new COND_CMP(and_father,func)))
	  save_list->push_back(tmp2);
      }
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      func->set_cmp_func();
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    }
  }
}

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/*
  Remove additional condition inserted by IN/ALL/ANY transformation

  SYNOPSIS
    remove_additional_cond()
    conds - condition for processing

  RETURN VALUES
    new conditions
*/

static Item *remove_additional_cond(Item* conds)
{
  if (conds->name == in_additional_cond)
    return 0;
  if (conds->type() == Item::COND_ITEM)
  {
    Item_cond *cnd= (Item_cond*) conds;
    List_iterator<Item> li(*(cnd->argument_list()));
    Item *item;
    while ((item= li++))
    {
      if (item->name == in_additional_cond)
      {
	li.remove();
	if (cnd->argument_list()->elements == 1)
	  return cnd->argument_list()->head();
	return conds;
      }
    }
  }
  return conds;
}
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static void
4649 4650
propagate_cond_constants(THD *thd, I_List<COND_CMP> *save_list,
                         COND *and_father, COND *cond)
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{
  if (cond->type() == Item::COND_ITEM)
  {
    bool and_level= ((Item_cond*) cond)->functype() ==
      Item_func::COND_AND_FUNC;
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    List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list());
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    Item *item;
    I_List<COND_CMP> save;
    while ((item=li++))
    {
4661
      propagate_cond_constants(thd, &save,and_level ? cond : item, item);
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    }
    if (and_level)
    {						// Handle other found items
      I_List_iterator<COND_CMP> cond_itr(save);
      COND_CMP *cond_cmp;
      while ((cond_cmp=cond_itr++))
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      {
        Item **args= cond_cmp->cmp_func->arguments();
        if (!args[0]->const_item())
          change_cond_ref_to_const(thd, &save,cond_cmp->and_level,
                                   cond_cmp->and_level, args[0], args[1]);
      }
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    }
  }
4676
  else if (and_father != cond && !cond->marker)		// In a AND group
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  {
    if (cond->type() == Item::FUNC_ITEM &&
	(((Item_func*) cond)->functype() == Item_func::EQ_FUNC ||
	 ((Item_func*) cond)->functype() == Item_func::EQUAL_FUNC))
    {
      Item_func_eq *func=(Item_func_eq*) cond;
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      Item **args= func->arguments();
      bool left_const= args[0]->const_item();
      bool right_const= args[1]->const_item();
4686
      if (!(left_const && right_const) &&
4687
          args[0]->result_type() == args[1]->result_type())
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      {
	if (right_const)
	{
4691
          resolve_const_item(thd, &args[1], args[0]);
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	  func->update_used_tables();
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          change_cond_ref_to_const(thd, save_list, and_father, and_father,
                                   args[0], args[1]);
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	}
	else if (left_const)
	{
4698
          resolve_const_item(thd, &args[0], args[1]);
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	  func->update_used_tables();
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          change_cond_ref_to_const(thd, save_list, and_father, and_father,
                                   args[1], args[0]);
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	}
      }
    }
  }
}


static COND *
4710
optimize_cond(THD *thd, COND *conds, Item::cond_result *cond_value)
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{
4712
  SELECT_LEX *select= thd->lex->current_select;
4713
  DBUG_ENTER("optimize_cond");
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  if (conds)
  {
    DBUG_EXECUTE("where", print_where(conds, "original"););
    /* change field = field to field = const for each found field = const */
4718
    propagate_cond_constants(thd, (I_List<COND_CMP> *) 0, conds, conds);
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    /*
      Remove all instances of item == item
      Remove all and-levels where CONST item != CONST item
    */
    DBUG_EXECUTE("where", print_where(conds, "after const change"););
    conds= remove_eq_conds(thd, conds, cond_value);
    DBUG_EXECUTE("info", print_where(conds, "after remove"););
  }
  else
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    *cond_value= Item::COND_TRUE;
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  DBUG_RETURN(conds);
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}


/*
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  Remove const and eq items. Return new item, or NULL if no condition
  cond_value is set to according:
  COND_OK    query is possible (field = constant)
  COND_TRUE  always true	( 1 = 1 )
  COND_FALSE always false	( 1 = 2 )
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*/

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COND *
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remove_eq_conds(THD *thd, COND *cond, Item::cond_result *cond_value)
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{
  if (cond->type() == Item::COND_ITEM)
  {
    bool and_level= ((Item_cond*) cond)->functype()
      == Item_func::COND_AND_FUNC;
    List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
    Item::cond_result tmp_cond_value;
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    bool should_fix_fields=0;
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    *cond_value=Item::COND_UNDEF;
    Item *item;
    while ((item=li++))
    {
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      Item *new_item=remove_eq_conds(thd, item, &tmp_cond_value);
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      if (!new_item)
	li.remove();
      else if (item != new_item)
      {
	VOID(li.replace(new_item));
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	should_fix_fields=1;
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      }
      if (*cond_value == Item::COND_UNDEF)
	*cond_value=tmp_cond_value;
      switch (tmp_cond_value) {
      case Item::COND_OK:			// Not TRUE or FALSE
	if (and_level || *cond_value == Item::COND_FALSE)
	  *cond_value=tmp_cond_value;
	break;
      case Item::COND_FALSE:
	if (and_level)
	{
	  *cond_value=tmp_cond_value;
	  return (COND*) 0;			// Always false
	}
	break;
      case Item::COND_TRUE:
	if (!and_level)
	{
	  *cond_value= tmp_cond_value;
	  return (COND*) 0;			// Always true
	}
	break;
      case Item::COND_UNDEF:			// Impossible
	break; /* purecov: deadcode */
      }
    }
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    if (should_fix_fields)
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      cond->update_used_tables();
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    if (!((Item_cond*) cond)->argument_list()->elements ||
	*cond_value != Item::COND_OK)
      return (COND*) 0;
    if (((Item_cond*) cond)->argument_list()->elements == 1)
    {						// Remove list
      item= ((Item_cond*) cond)->argument_list()->head();
      ((Item_cond*) cond)->argument_list()->empty();
      return item;
    }
  }
  else if (cond->type() == Item::FUNC_ITEM &&
	   ((Item_func*) cond)->functype() == Item_func::ISNULL_FUNC)
  {
    /*
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      Handles this special case for some ODBC applications:
      The are requesting the row that was just updated with a auto_increment
      value with this construct:

      SELECT * from table_name where auto_increment_column IS NULL
      This will be changed to:
      SELECT * from table_name where auto_increment_column = LAST_INSERT_ID
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    */

    Item_func_isnull *func=(Item_func_isnull*) cond;
    Item **args= func->arguments();
    if (args[0]->type() == Item::FIELD_ITEM)
    {
      Field *field=((Item_field*) args[0])->field;
      if (field->flags & AUTO_INCREMENT_FLAG && !field->table->maybe_null &&
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	  (thd->options & OPTION_AUTO_IS_NULL) &&
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	  thd->insert_id() && thd->substitute_null_with_insert_id)
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      {
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#ifdef HAVE_QUERY_CACHE
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	query_cache_abort(&thd->net);
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#endif
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	COND *new_cond;
	if ((new_cond= new Item_func_eq(args[0],
					new Item_int("last_insert_id()",
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						     thd->insert_id(),
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						     21))))
	{
	  cond=new_cond;
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	  cond->fix_fields(thd, 0, &cond);
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	}
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	thd->substitute_null_with_insert_id= FALSE;   // Clear for next request
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      }
      /* fix to replace 'NULL' dates with '0' (shreeve@uci.edu) */
      else if (((field->type() == FIELD_TYPE_DATE) ||
		(field->type() == FIELD_TYPE_DATETIME)) &&
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		(field->flags & NOT_NULL_FLAG) &&
	       !field->table->maybe_null)
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      {
	COND *new_cond;
	if ((new_cond= new Item_func_eq(args[0],new Item_int("0", 0, 2))))
	{
	  cond=new_cond;
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	  cond->fix_fields(thd, 0, &cond);
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	}
      }
    }
  }
  else if (cond->const_item())
  {
    *cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE;
    return (COND*) 0;
  }
  else if ((*cond_value= cond->eq_cmp_result()) != Item::COND_OK)
  {						// boolan compare function
    Item *left_item=	((Item_func*) cond)->arguments()[0];
    Item *right_item= ((Item_func*) cond)->arguments()[1];
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    if (left_item->eq(right_item,1))
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    {
      if (!left_item->maybe_null ||
	  ((Item_func*) cond)->functype() == Item_func::EQUAL_FUNC)
	return (COND*) 0;			// Compare of identical items
    }
  }
  *cond_value=Item::COND_OK;
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  return cond;					// Point at next and level
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}

/*
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  Return 1 if the item is a const value in all the WHERE clause
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*/

static bool
const_expression_in_where(COND *cond, Item *comp_item, Item **const_item)
{
  if (cond->type() == Item::COND_ITEM)
  {
    bool and_level= (((Item_cond*) cond)->functype()
		     == Item_func::COND_AND_FUNC);
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    List_iterator_fast<Item> li(*((Item_cond*) cond)->argument_list());
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    Item *item;
    while ((item=li++))
    {
      bool res=const_expression_in_where(item, comp_item, const_item);
      if (res)					// Is a const value
      {
	if (and_level)
	  return 1;
      }
      else if (!and_level)
	return 0;
    }
    return and_level ? 0 : 1;
  }
  else if (cond->eq_cmp_result() != Item::COND_OK)
  {						// boolan compare function
    Item_func* func= (Item_func*) cond;
    if (func->functype() != Item_func::EQUAL_FUNC &&
	func->functype() != Item_func::EQ_FUNC)
      return 0;
    Item *left_item=	((Item_func*) cond)->arguments()[0];
    Item *right_item= ((Item_func*) cond)->arguments()[1];
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    if (left_item->eq(comp_item,1))
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    {
      if (right_item->const_item())
      {
	if (*const_item)
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	  return right_item->eq(*const_item, 1);
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	*const_item=right_item;
	return 1;
      }
    }
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    else if (right_item->eq(comp_item,1))
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    {
      if (left_item->const_item())
      {
	if (*const_item)
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	  return left_item->eq(*const_item, 1);
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	*const_item=left_item;
	return 1;
      }
    }
  }
  return 0;
}


/****************************************************************************
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  Create internal temporary table
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****************************************************************************/

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/*
  Create field for temporary table from given field
  
  SYNOPSIS
    create_tmp_field_from_field()
    thd			Thread handler
    org_field           field from which new field will be created
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    name                New field name
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    item		Item to create a field for
    table		Temporary table
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    item	        !=NULL if item->result_field should point to new field.
			This is relevant for how fill_record() is going to work:
			If item != NULL then fill_record() will update
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			the record in the original table.
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			If item == NULL then fill_record() will update
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			the temporary table
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    convert_blob_length If >0 create a varstring(convert_blob_length) field 
                        instead of blob.
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  RETURN
    0			on error
    new_created field
*/
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static Field* create_tmp_field_from_field(THD *thd, Field* org_field,
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                                          const char *name, TABLE *table,
                                          Item_field *item,
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                                          uint convert_blob_length)
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{
  Field *new_field;

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  if (convert_blob_length && org_field->flags & BLOB_FLAG)
    new_field= new Field_varstring(convert_blob_length, org_field->maybe_null(),
                                   org_field->field_name, table,
                                   org_field->charset());
  else
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    new_field= org_field->new_field(thd->mem_root, table);
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  if (new_field)
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  {
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    if (item)
      item->result_field= new_field;
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    else
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      new_field->field_name= name;
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    if (org_field->maybe_null() || (item && item->maybe_null))
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      new_field->flags&= ~NOT_NULL_FLAG;	// Because of outer join
    if (org_field->type() == FIELD_TYPE_VAR_STRING)
      table->db_create_options|= HA_OPTION_PACK_RECORD;
  }
  return new_field;
}

/*
  Create field for temporary table using type of given item
  
  SYNOPSIS
    create_tmp_field_from_item()
    thd			Thread handler
    item		Item to create a field for
    table		Temporary table
    copy_func		If set and item is a function, store copy of item
			in this array
    modify_item		1 if item->result_field should point to new item.
			This is relevent for how fill_record() is going to
			work:
			If modify_item is 1 then fill_record() will update
			the record in the original table.
			If modify_item is 0 then fill_record() will update
			the temporary table
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    convert_blob_length If >0 create a varstring(convert_blob_length) field 
                        instead of blob.
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  RETURN
    0			on error
    new_created field
*/
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static Field* create_tmp_field_from_item(THD *thd, Item *item, TABLE *table,
                                         Item ***copy_func, bool modify_item,
                                         uint convert_blob_length)
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{
  bool maybe_null=item->maybe_null;
  Field *new_field;
  LINT_INIT(new_field);

  switch (item->result_type()) {
  case REAL_RESULT:
    new_field=new Field_double(item->max_length, maybe_null,
			       item->name, table, item->decimals);
    break;
  case INT_RESULT:
    new_field=new Field_longlong(item->max_length, maybe_null,
				   item->name, table, item->unsigned_flag);
    break;
  case STRING_RESULT:
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    DBUG_ASSERT(item->collation.collation);
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    enum enum_field_types type;
    /*
      DATE/TIME fields have STRING_RESULT result type. To preserve
      type they needed to be handled separately.
    */
    if ((type= item->field_type()) == MYSQL_TYPE_DATETIME ||
        type == MYSQL_TYPE_TIME || type == MYSQL_TYPE_DATE)
      new_field= item->tmp_table_field_from_field_type(table);
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    else if (item->max_length/item->collation.collation->mbmaxlen >
             CONVERT_IF_BIGGER_TO_BLOB)
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    {
      if (convert_blob_length)
        new_field= new Field_varstring(convert_blob_length, maybe_null,
                                       item->name, table,
                                       item->collation.collation);
      else
        new_field= new Field_blob(item->max_length, maybe_null, item->name,
                                  table, item->collation.collation);
    }
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    else
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      new_field= new Field_string(item->max_length, maybe_null, item->name, 
                                  table, item->collation.collation);
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    break;
  case ROW_RESULT: 
  default: 
    // This case should never be choosen
    DBUG_ASSERT(0);
    new_field= 0; // to satisfy compiler (uninitialized variable)
    break;
  }
  if (copy_func && item->is_result_field())
    *((*copy_func)++) = item;			// Save for copy_funcs
  if (modify_item)
    item->set_result_field(new_field);
  return new_field;
}

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/*
  Create field for temporary table

  SYNOPSIS
    create_tmp_field()
    thd			Thread handler
    table		Temporary table
    item		Item to create a field for
    type		Type of item (normally item->type)
    copy_func		If set and item is a function, store copy of item
			in this array
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    from_field          if field will be created using other field as example,
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                        pointer example field will be written here
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    group		1 if we are going to do a relative group by on result
    modify_item		1 if item->result_field should point to new item.
			This is relevent for how fill_record() is going to
			work:
			If modify_item is 1 then fill_record() will update
			the record in the original table.
			If modify_item is 0 then fill_record() will update
			the temporary table
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    convert_blob_length If >0 create a varstring(convert_blob_length) field 
                        instead of blob.
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  RETURN
    0			on error
    new_created field
*/

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Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
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                        Item ***copy_func, Field **from_field,
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                        bool group, bool modify_item, uint convert_blob_length,
                        bool make_copy_field)
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{
  switch (type) {
  case Item::SUM_FUNC_ITEM:
  {
    Item_sum *item_sum=(Item_sum*) item;
    bool maybe_null=item_sum->maybe_null;
    switch (item_sum->sum_func()) {
    case Item_sum::AVG_FUNC:			/* Place for sum & count */
      if (group)
	return new Field_string(sizeof(double)+sizeof(longlong),
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				0, item->name,table,&my_charset_bin);
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      else
	return new Field_double(item_sum->max_length,maybe_null,
				item->name, table, item_sum->decimals);
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    case Item_sum::VARIANCE_FUNC:		/* Place for sum & count */
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    case Item_sum::STD_FUNC:
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      if (group)
	return	new Field_string(sizeof(double)*2+sizeof(longlong),
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				 0, item->name,table,&my_charset_bin);
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      else
	return new Field_double(item_sum->max_length, maybe_null,
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				item->name,table,item_sum->decimals);
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    case Item_sum::UNIQUE_USERS_FUNC:
      return new Field_long(9,maybe_null,item->name,table,1);
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    case Item_sum::MIN_FUNC:
    case Item_sum::MAX_FUNC:
      if (item_sum->args[0]->type() == Item::FIELD_ITEM)
      {
        *from_field= ((Item_field*) item_sum->args[0])->field;
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        return create_tmp_field_from_field(thd, *from_field, item->name, table,
                                           NULL, convert_blob_length);
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      }
      /* fall through */
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    default:
      switch (item_sum->result_type()) {
      case REAL_RESULT:
	return new Field_double(item_sum->max_length,maybe_null,
				item->name,table,item_sum->decimals);
      case INT_RESULT:
	return new Field_longlong(item_sum->max_length,maybe_null,
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				  item->name,table,item->unsigned_flag);
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      case STRING_RESULT:
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	if (item_sum->max_length/item_sum->collation.collation->mbmaxlen >
            CONVERT_IF_BIGGER_TO_BLOB)
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        {
          if (convert_blob_length)
            return new Field_varstring(convert_blob_length, maybe_null,
                                       item->name, table,
                                       item->collation.collation);
          else
            return new Field_blob(item_sum->max_length, maybe_null, item->name,
                                  table, item->collation.collation);
        }
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	return	new Field_string(item_sum->max_length,maybe_null,
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				 item->name,table,item->collation.collation);
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      case ROW_RESULT:
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      default:
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	// This case should never be choosen
	DBUG_ASSERT(0);
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	thd->fatal_error();
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	return 0;
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      }
    }
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    /* We never come here */
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  }
  case Item::FIELD_ITEM:
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  case Item::DEFAULT_VALUE_ITEM:
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  {
    Item_field *field= (Item_field*) item;
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    return create_tmp_field_from_field(thd, (*from_field= field->field),
                                       item->name, table,
                                       modify_item ? (Item_field*) item : NULL,
                                       convert_blob_length);
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  }
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  case Item::FUNC_ITEM:
  case Item::COND_ITEM:
  case Item::FIELD_AVG_ITEM:
  case Item::FIELD_STD_ITEM:
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  case Item::SUBSELECT_ITEM:
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    /* The following can only happen with 'CREATE TABLE ... SELECT' */
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  case Item::PROC_ITEM:
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  case Item::INT_ITEM:
  case Item::REAL_ITEM:
  case Item::STRING_ITEM:
  case Item::REF_ITEM:
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  case Item::NULL_ITEM:
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  case Item::VARBIN_ITEM:
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    if (make_copy_field)
    {
      DBUG_ASSERT(((Item_result_field*)item)->result_field);
      *from_field= ((Item_result_field*)item)->result_field;
    }
    return create_tmp_field_from_item(thd, item, table, (make_copy_field ? 0 :
                                      copy_func), modify_item,
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                                      convert_blob_length);
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  case Item::TYPE_HOLDER:
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    return ((Item_type_holder *)item)->make_field_by_type(table);
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  default:					// Dosen't have to be stored
    return 0;
  }
}


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/*
  Create a temp table according to a field list.
  Set distinct if duplicates could be removed
  Given fields field pointers are changed to point at tmp_table
  for send_fields
*/

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TABLE *
create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
		 ORDER *group, bool distinct, bool save_sum_fields,
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		 ulong select_options, ha_rows rows_limit,
		 char *table_alias)
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{
  TABLE *table;
  uint	i,field_count,reclength,null_count,null_pack_length,
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        hidden_null_count, hidden_null_pack_length, hidden_field_count,
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	blob_count,group_null_items;
  bool	using_unique_constraint=0;
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  bool  not_all_columns= !(select_options & TMP_TABLE_ALL_COLUMNS);
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  char	*tmpname,path[FN_REFLEN];
  byte	*pos,*group_buff;
  uchar *null_flags;
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  Field **reg_field, **from_field, **blob_field;
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  Copy_field *copy=0;
  KEY *keyinfo;
  KEY_PART_INFO *key_part_info;
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  Item **copy_func;
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  MI_COLUMNDEF *recinfo;
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  uint temp_pool_slot=MY_BIT_NONE;
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  bool force_copy_fields= param->force_copy_fields;
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  DBUG_ENTER("create_tmp_table");
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  DBUG_PRINT("enter",("distinct: %d  save_sum_fields: %d  rows_limit: %lu  group: %d",
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		      (int) distinct, (int) save_sum_fields,
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		      (ulong) rows_limit,test(group)));
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  statistic_increment(created_tmp_tables, &LOCK_status);
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5242
  if (use_temp_pool)
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    temp_pool_slot = bitmap_set_next(&temp_pool);
5244 5245

  if (temp_pool_slot != MY_BIT_NONE) // we got a slot
5246
    sprintf(path, "%s_%lx_%i", tmp_file_prefix,
5247 5248
	    current_pid, temp_pool_slot);
  else // if we run out of slots or we are not using tempool
5249
    sprintf(path,"%s%lx_%lx_%x", tmp_file_prefix,current_pid,
5250
            thd->thread_id, thd->tmp_table++);
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5251

5252 5253
  fn_format(path, path, mysql_tmpdir, "", MY_REPLACE_EXT|MY_UNPACK_FILENAME);

5254 5255
  if (lower_case_table_names)
    my_casedn_str(files_charset_info, path);
5256

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  if (group)
  {
    if (!param->quick_group)
      group=0;					// Can't use group key
    else for (ORDER *tmp=group ; tmp ; tmp=tmp->next)
5262
    {
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      (*tmp->item)->marker=4;			// Store null in key
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      if ((*tmp->item)->max_length >= MAX_CHAR_WIDTH)
	using_unique_constraint=1;
    }
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    if (param->group_length >= MAX_BLOB_WIDTH)
      using_unique_constraint=1;
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    if (group)
      distinct=0;				// Can't use distinct
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  }

  field_count=param->field_count+param->func_count+param->sum_func_count;
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  hidden_field_count=param->hidden_field_count;
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  if (!my_multi_malloc(MYF(MY_WME),
		       &table,sizeof(*table),
5277 5278 5279
		       &reg_field,  sizeof(Field*)*(field_count+1),
		       &blob_field, sizeof(Field*)*(field_count+1),
		       &from_field, sizeof(Field*)*field_count,
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		       &copy_func,sizeof(*copy_func)*(param->func_count+1),
		       &param->keyinfo,sizeof(*param->keyinfo),
		       &key_part_info,
		       sizeof(*key_part_info)*(param->group_parts+1),
		       &param->start_recinfo,
		       sizeof(*param->recinfo)*(field_count*2+4),
		       &tmpname,(uint) strlen(path)+1,
		       &group_buff,group && ! using_unique_constraint ?
		       param->group_length : 0,
		       NullS))
  {
5291 5292
    if (temp_pool_slot != MY_BIT_NONE)
      bitmap_clear_bit(&temp_pool, temp_pool_slot);
5293
    DBUG_RETURN(NULL);				/* purecov: inspected */
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  }
  if (!(param->copy_field=copy=new Copy_field[field_count]))
  {
5297 5298
    if (temp_pool_slot != MY_BIT_NONE)
      bitmap_clear_bit(&temp_pool, temp_pool_slot);
5299 5300
    my_free((gptr) table,MYF(0));		/* purecov: inspected */
    DBUG_RETURN(NULL);				/* purecov: inspected */
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  }
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  param->items_to_copy= copy_func;
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  strmov(tmpname,path);
  /* make table according to fields */

  bzero((char*) table,sizeof(*table));
  bzero((char*) reg_field,sizeof(Field*)*(field_count+1));
  bzero((char*) from_field,sizeof(Field*)*field_count);
  table->field=reg_field;
5310
  table->blob_field= (Field_blob**) blob_field;
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  table->real_name=table->path=tmpname;
5312
  table->table_name= table_alias;
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  table->reginfo.lock_type=TL_WRITE;	/* Will be updated */
  table->db_stat=HA_OPEN_KEYFILE+HA_OPEN_RNDFILE;
  table->blob_ptr_size=mi_portable_sizeof_char_ptr;
  table->map=1;
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  table->tmp_table= TMP_TABLE;
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  table->db_low_byte_first=1;			// True for HEAP and MyISAM
5319
  table->temp_pool_slot = temp_pool_slot;
5320
  table->copy_blobs= 1;
5321
  table->in_use= thd;
5322 5323 5324 5325 5326 5327
  table->keys_for_keyread.init();
  table->keys_in_use.init();
  table->read_only_keys.init();
  table->quick_keys.init();
  table->used_keys.init();
  table->keys_in_use_for_query.init();
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5328

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  /* Calculate which type of fields we will store in the temporary table */
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  reclength=blob_count=null_count=hidden_null_count=group_null_items=0;
  param->using_indirect_summary_function=0;
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  List_iterator_fast<Item> li(fields);
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  Item *item;
  Field **tmp_from_field=from_field;
5337
  while ((item=li++))
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  {
    Item::Type type=item->type();
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    if (not_all_columns)
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    {
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      if (item->with_sum_func && type != Item::SUM_FUNC_ITEM)
      {
	/*
	  Mark that the we have ignored an item that refers to a summary
	  function. We need to know this if someone is going to use
	  DISTINCT on the result.
	*/
	param->using_indirect_summary_function=1;
	continue;
      }
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      if (item->const_item() && (int) hidden_field_count <= 0)
5353
        continue; // We don't have to store this
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    }
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    if (type == Item::SUM_FUNC_ITEM && !group && !save_sum_fields)
    {						/* Can't calc group yet */
      ((Item_sum*) item)->result_field=0;
      for (i=0 ; i < ((Item_sum*) item)->arg_count ; i++)
      {
5360 5361
	Item **argp= ((Item_sum*) item)->args + i;
	Item *arg= *argp;
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	if (!arg->const_item())
	{
	  Field *new_field=
5365 5366
            create_tmp_field(thd, table, arg, arg->type(), &copy_func,
                             tmp_from_field, group != 0,not_all_columns,
5367
                             param->convert_blob_length, 0);
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	  if (!new_field)
	    goto err;					// Should be OOM
	  tmp_from_field++;
	  *(reg_field++)= new_field;
	  reclength+=new_field->pack_length();
	  if (new_field->flags & BLOB_FLAG)
5374 5375
	  {
	    *blob_field++= new_field;
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5376
	    blob_count++;
5377
	  }
5378
          thd->change_item_tree(argp, new Item_field(new_field));
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	  if (!(new_field->flags & NOT_NULL_FLAG))
          {
	    null_count++;
            /*
              new_field->maybe_null() is still false, it will be
              changed below. But we have to setup Item_field correctly
            */
5386
            (*argp)->maybe_null=1;
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          }
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	}
      }
    }
    else
    {
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      /*
	The last parameter to create_tmp_field() is a bit tricky:

	We need to set it to 0 in union, to get fill_record() to modify the
	temporary table.
	We need to set it to 1 on multi-table-update and in select to
	write rows to the temporary table.
	We here distinguish between UNION and multi-table-updates by the fact
	that in the later case group is set to the row pointer.
      */
5403 5404
      Field *new_field= create_tmp_field(thd, table, item, type, &copy_func,
                                         tmp_from_field, group != 0,
5405 5406 5407 5408
                                         !force_copy_fields &&
                                           (not_all_columns || group !=0),
                                         param->convert_blob_length,
                                         force_copy_fields);
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5409 5410
      if (!new_field)
      {
5411
	if (thd->is_fatal_error)
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	  goto err;				// Got OOM
	continue;				// Some kindf of const item
      }
      if (type == Item::SUM_FUNC_ITEM)
	((Item_sum *) item)->result_field= new_field;
      tmp_from_field++;
      reclength+=new_field->pack_length();
      if (!(new_field->flags & NOT_NULL_FLAG))
	null_count++;
      if (new_field->flags & BLOB_FLAG)
5422 5423
      {
	*blob_field++= new_field;
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5424
	blob_count++;
5425
      }
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      if (item->marker == 4 && item->maybe_null)
      {
	group_null_items++;
	new_field->flags|= GROUP_FLAG;
      }
      *(reg_field++) =new_field;
    }
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5433
    if (!--hidden_field_count)
5434
    {
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      hidden_null_count=null_count;
5436 5437 5438 5439 5440 5441
      /*
        We need to update hidden_field_count as we may have stored group
        functions with constant arguments
      */
      param->hidden_field_count= (uint) (reg_field - table->field);
    }
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5442
  }
5443
  DBUG_ASSERT(field_count >= (uint) (reg_field - table->field));
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  field_count= (uint) (reg_field - table->field);
5445
  *blob_field= 0;				// End marker
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  /* If result table is small; use a heap */
5448
  if (blob_count || using_unique_constraint ||
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      (select_options & (OPTION_BIG_TABLES | SELECT_SMALL_RESULT)) ==
5450
      OPTION_BIG_TABLES ||(select_options & TMP_TABLE_FORCE_MYISAM))
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  {
    table->file=get_new_handler(table,table->db_type=DB_TYPE_MYISAM);
    if (group &&
	(param->group_parts > table->file->max_key_parts() ||
	 param->group_length > table->file->max_key_length()))
      using_unique_constraint=1;
  }
  else
  {
    table->file=get_new_handler(table,table->db_type=DB_TYPE_HEAP);
  }

  if (!using_unique_constraint)
    reclength+= group_null_items;	// null flag is stored separately

  table->blob_fields=blob_count;
  if (blob_count == 0)
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  {
    /* We need to ensure that first byte is not 0 for the delete link */
5470
    if (param->hidden_field_count)
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      hidden_null_count++;
    else
      null_count++;
  }
  hidden_null_pack_length=(hidden_null_count+7)/8;
  null_pack_length=hidden_null_count+(null_count+7)/8;
  reclength+=null_pack_length;
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  if (!reclength)
    reclength=1;				// Dummy select

  table->fields=field_count;
  table->reclength=reclength;
  {
    uint alloc_length=ALIGN_SIZE(reclength+MI_UNIQUE_HASH_LENGTH+1);
    table->rec_buff_length=alloc_length;
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5486
    if (!(table->record[0]= (byte *) my_malloc(alloc_length*3, MYF(MY_WME))))
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      goto err;
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    table->record[1]= table->record[0]+alloc_length;
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    table->default_values= table->record[1]+alloc_length;
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  }
  copy_func[0]=0;				// End marker

  recinfo=param->start_recinfo;
  null_flags=(uchar*) table->record[0];
  pos=table->record[0]+ null_pack_length;
  if (null_pack_length)
  {
    bzero((byte*) recinfo,sizeof(*recinfo));
    recinfo->type=FIELD_NORMAL;
    recinfo->length=null_pack_length;
    recinfo++;
    bfill(null_flags,null_pack_length,255);	// Set null fields
5503 5504 5505 5506

    table->null_flags= (uchar*) table->record[0];
    table->null_fields= null_count+ hidden_null_count;
    table->null_bytes= null_pack_length;
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  }
  null_count= (blob_count == 0) ? 1 : 0;
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  hidden_field_count=param->hidden_field_count;
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  for (i=0,reg_field=table->field; i < field_count; i++,reg_field++,recinfo++)
  {
    Field *field= *reg_field;
    uint length;
    bzero((byte*) recinfo,sizeof(*recinfo));

    if (!(field->flags & NOT_NULL_FLAG))
    {
      if (field->flags & GROUP_FLAG && !using_unique_constraint)
      {
5520 5521 5522 5523
	/*
	  We have to reserve one byte here for NULL bits,
	  as this is updated by 'end_update()'
	*/
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	*pos++=0;				// Null is stored here
	recinfo->length=1;
	recinfo->type=FIELD_NORMAL;
	recinfo++;
	bzero((byte*) recinfo,sizeof(*recinfo));
      }
      else
      {
	recinfo->null_bit= 1 << (null_count & 7);
	recinfo->null_pos= null_count/8;
      }
      field->move_field((char*) pos,null_flags+null_count/8,
			1 << (null_count & 7));
      null_count++;
    }
    else
      field->move_field((char*) pos,(uchar*) 0,0);
    field->reset();
    if (from_field[i])
    {						/* Not a table Item */
      copy->set(field,from_field[i],save_sum_fields);
      copy++;
    }
    length=field->pack_length();
    pos+= length;

    /* Make entry for create table */
    recinfo->length=length;
    if (field->flags & BLOB_FLAG)
      recinfo->type= (int) FIELD_BLOB;
    else if (!field->zero_pack() &&
	     (field->type() == FIELD_TYPE_STRING ||
	      field->type() == FIELD_TYPE_VAR_STRING) &&
	     length >= 10 && blob_count)
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      recinfo->type=FIELD_SKIP_ENDSPACE;
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    else
      recinfo->type=FIELD_NORMAL;
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    if (!--hidden_field_count)
      null_count=(null_count+7) & ~7;		// move to next byte
5563 5564 5565

    // fix table name in field entry
    field->table_name= table->table_name;
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  }

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  param->copy_field_end=copy;
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5569
  param->recinfo=recinfo;
5570
  store_record(table,default_values);		// Make empty default record
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5571

5572
  if (thd->variables.tmp_table_size == ~(ulong) 0)		// No limit
5573 5574 5575
    table->max_rows= ~(ha_rows) 0;
  else
    table->max_rows=(((table->db_type == DB_TYPE_HEAP) ?
5576 5577 5578
		      min(thd->variables.tmp_table_size,
			  thd->variables.max_heap_table_size) :
		      thd->variables.tmp_table_size)/ table->reclength);
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5579
  set_if_bigger(table->max_rows,1);		// For dummy start options
5580 5581 5582 5583 5584 5585 5586
  /*
    Push the LIMIT clause to the temporary table creation, so that we
    materialize only up to 'rows_limit' records instead of all result records.
  */
  set_if_smaller(table->max_rows, rows_limit);
  param->end_write_records= rows_limit;

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  keyinfo=param->keyinfo;

  if (group)
  {
    DBUG_PRINT("info",("Creating group key in temporary table"));
    table->group=group;				/* Table is grouped by key */
    param->group_buff=group_buff;
    table->keys=1;
    table->uniques= test(using_unique_constraint);
    table->key_info=keyinfo;
    keyinfo->key_part=key_part_info;
    keyinfo->flags=HA_NOSAME;
    keyinfo->usable_key_parts=keyinfo->key_parts= param->group_parts;
    keyinfo->key_length=0;
    keyinfo->rec_per_key=0;
5602
    keyinfo->algorithm= HA_KEY_ALG_UNDEF;
5603 5604
    ORDER *cur_group= group;
    for (; cur_group ; cur_group= cur_group->next, key_part_info++)
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    {
5606 5607
      Field *field=(*cur_group->item)->get_tmp_table_field();
      bool maybe_null=(*cur_group->item)->maybe_null;
5608
      key_part_info->null_bit=0;
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      key_part_info->field=  field;
      key_part_info->offset= field->offset();
      key_part_info->length= (uint16) field->pack_length();
      key_part_info->type=   (uint8) field->key_type();
      key_part_info->key_type =
	((ha_base_keytype) key_part_info->type == HA_KEYTYPE_TEXT ||
	 (ha_base_keytype) key_part_info->type == HA_KEYTYPE_VARTEXT) ?
	0 : FIELDFLAG_BINARY;
      if (!using_unique_constraint)
      {
5619 5620
	cur_group->buff=(char*) group_buff;
	if (!(cur_group->field=field->new_field(thd->mem_root,table)))
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	  goto err; /* purecov: inspected */
	if (maybe_null)
	{
	  /*
5625 5626 5627 5628
	    To be able to group on NULL, we reserve place in group_buff
	    for the NULL flag just before the column.
	    The field data is after this flag.
	    The NULL flag is updated by 'end_update()' and 'end_write()'
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	  */
5630 5631 5632 5633
	  keyinfo->flags|= HA_NULL_ARE_EQUAL;	// def. that NULL == NULL
	  key_part_info->null_bit=field->null_bit;
	  key_part_info->null_offset= (uint) (field->null_ptr -
					      (uchar*) table->record[0]);
5634
	  cur_group->field->move_field((char*) ++cur_group->buff);
5635
	  group_buff++;
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	}
	else
5638
	  cur_group->field->move_field((char*) group_buff);
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	group_buff+= key_part_info->length;
      }
      keyinfo->key_length+=  key_part_info->length;
    }
  }

5645
  if (distinct && field_count != param->hidden_field_count)
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5646
  {
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    /*
      Create an unique key or an unique constraint over all columns
      that should be in the result.  In the temporary table, there are
      'param->hidden_field_count' extra columns, whose null bits are stored
      in the first 'hidden_null_pack_length' bytes of the row.
    */
5653 5654
    DBUG_PRINT("info",("hidden_field_count: %d", param->hidden_field_count));

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    null_pack_length-=hidden_null_pack_length;
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    keyinfo->key_parts= ((field_count-param->hidden_field_count)+
5657
			 test(null_pack_length));
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    table->distinct=1;
    table->keys=1;
    if (blob_count)
    {
      using_unique_constraint=1;
      table->uniques=1;
    }
    if (!(key_part_info= (KEY_PART_INFO*)
	  sql_calloc((keyinfo->key_parts)*sizeof(KEY_PART_INFO))))
      goto err;
    table->key_info=keyinfo;
    keyinfo->key_part=key_part_info;
5670
    keyinfo->flags=HA_NOSAME | HA_NULL_ARE_EQUAL;
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    keyinfo->key_length=(uint16) reclength;
    keyinfo->name=(char*) "tmp";
5673
    keyinfo->algorithm= HA_KEY_ALG_UNDEF;
5674
    keyinfo->rec_per_key=0;
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    if (null_pack_length)
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    {
5677
      key_part_info->null_bit=0;
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      key_part_info->offset=hidden_null_pack_length;
      key_part_info->length=null_pack_length;
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      key_part_info->field=new Field_string((char*) table->record[0],
					    (uint32) key_part_info->length,
					    (uchar*) 0,
					    (uint) 0,
					    Field::NONE,
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					    NullS, table, &my_charset_bin);
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      key_part_info->key_type=FIELDFLAG_BINARY;
      key_part_info->type=    HA_KEYTYPE_BINARY;
      key_part_info++;
    }
5690
    /* Create a distinct key over the columns we are going to return */
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    for (i=param->hidden_field_count, reg_field=table->field + i ;
	 i < field_count;
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	 i++, reg_field++, key_part_info++)
    {
5695
      key_part_info->null_bit=0;
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      key_part_info->field=    *reg_field;
      key_part_info->offset=   (*reg_field)->offset();
      key_part_info->length=   (uint16) (*reg_field)->pack_length();
      key_part_info->type=     (uint8) (*reg_field)->key_type();
      key_part_info->key_type =
	((ha_base_keytype) key_part_info->type == HA_KEYTYPE_TEXT ||
	 (ha_base_keytype) key_part_info->type == HA_KEYTYPE_VARTEXT) ?
	0 : FIELDFLAG_BINARY;
    }
  }
5706

5707
  if (thd->is_fatal_error)				// If end of memory
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    goto err;					 /* purecov: inspected */
  table->db_record_offset=1;
  if (table->db_type == DB_TYPE_MYISAM)
  {
    if (create_myisam_tmp_table(table,param,select_options))
      goto err;
  }
  if (!open_tmp_table(table))
    DBUG_RETURN(table);

 err:
5719 5720 5721 5722 5723
  /*
    Hack to ensure that free_blobs() doesn't fail if blob_field is not yet
    complete
  */
  *table->blob_field= 0;
5724
  free_tmp_table(thd,table);                    /* purecov: inspected */
5725 5726
  if (temp_pool_slot != MY_BIT_NONE)
    bitmap_clear_bit(&temp_pool, temp_pool_slot);
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  DBUG_RETURN(NULL);				/* purecov: inspected */
}


static bool open_tmp_table(TABLE *table)
{
  int error;
  if ((error=table->file->ha_open(table->real_name,O_RDWR,HA_OPEN_TMP_TABLE)))
  {
    table->file->print_error(error,MYF(0)); /* purecov: inspected */
    table->db_stat=0;
    return(1);
  }
  (void) table->file->extra(HA_EXTRA_QUICK);		/* Faster */
  return(0);
}


static bool create_myisam_tmp_table(TABLE *table,TMP_TABLE_PARAM *param,
5746
				    ulong options)
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{
  int error;
  MI_KEYDEF keydef;
  MI_UNIQUEDEF uniquedef;
  KEY *keyinfo=param->keyinfo;

  DBUG_ENTER("create_myisam_tmp_table");
  if (table->keys)
  {						// Get keys for ni_create
    bool using_unique_constraint=0;
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    HA_KEYSEG *seg= (HA_KEYSEG*) sql_calloc(sizeof(*seg) *
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					    keyinfo->key_parts);
    if (!seg)
      goto err;

    if (keyinfo->key_length >= table->file->max_key_length() ||
	keyinfo->key_parts > table->file->max_key_parts() ||
	table->uniques)
    {
      /* Can't create a key; Make a unique constraint instead of a key */
      table->keys=0;
      table->uniques=1;
      using_unique_constraint=1;
      bzero((char*) &uniquedef,sizeof(uniquedef));
      uniquedef.keysegs=keyinfo->key_parts;
      uniquedef.seg=seg;
      uniquedef.null_are_equal=1;

      /* Create extra column for hash value */
      bzero((byte*) param->recinfo,sizeof(*param->recinfo));
      param->recinfo->type= FIELD_CHECK;
      param->recinfo->length=MI_UNIQUE_HASH_LENGTH;
      param->recinfo++;
      table->reclength+=MI_UNIQUE_HASH_LENGTH;
    }
    else
    {
      /* Create an unique key */
      bzero((char*) &keydef,sizeof(keydef));
      keydef.flag=HA_NOSAME | HA_BINARY_PACK_KEY | HA_PACK_KEY;
      keydef.keysegs=  keyinfo->key_parts;
      keydef.seg= seg;
    }
    for (uint i=0; i < keyinfo->key_parts ; i++,seg++)
    {
      Field *field=keyinfo->key_part[i].field;
5793
      seg->flag=     0;
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      seg->language= field->charset()->number;
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      seg->length=   keyinfo->key_part[i].length;
      seg->start=    keyinfo->key_part[i].offset;
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      if (field->flags & BLOB_FLAG)
      {
	seg->type=
	((keyinfo->key_part[i].key_type & FIELDFLAG_BINARY) ?
	 HA_KEYTYPE_VARBINARY : HA_KEYTYPE_VARTEXT);
	seg->bit_start=seg->length - table->blob_ptr_size;
	seg->flag= HA_BLOB_PART;
	seg->length=0;			// Whole blob in unique constraint
      }
      else
      {
	seg->type=
	  ((keyinfo->key_part[i].key_type & FIELDFLAG_BINARY) ?
	   HA_KEYTYPE_BINARY : HA_KEYTYPE_TEXT);
	if (!(field->flags & ZEROFILL_FLAG) &&
	    (field->type() == FIELD_TYPE_STRING ||
	     field->type() == FIELD_TYPE_VAR_STRING) &&
	    keyinfo->key_part[i].length > 4)
	  seg->flag|=HA_SPACE_PACK;
      }
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      if (!(field->flags & NOT_NULL_FLAG))
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      {
	seg->null_bit= field->null_bit;
	seg->null_pos= (uint) (field->null_ptr - (uchar*) table->record[0]);
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	/*
	  We are using a GROUP BY on something that contains NULL
	  In this case we have to tell MyISAM that two NULL should
	  on INSERT be compared as equal
	*/
	if (!using_unique_constraint)
	  keydef.flag|= HA_NULL_ARE_EQUAL;
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      }
    }
  }
  MI_CREATE_INFO create_info;
  bzero((char*) &create_info,sizeof(create_info));
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5834 5835
  if ((options & (OPTION_BIG_TABLES | SELECT_SMALL_RESULT)) ==
      OPTION_BIG_TABLES)
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    create_info.data_file_length= ~(ulonglong) 0;

  if ((error=mi_create(table->real_name,table->keys,&keydef,
		       (uint) (param->recinfo-param->start_recinfo),
		       param->start_recinfo,
		       table->uniques, &uniquedef,
		       &create_info,
		       HA_CREATE_TMP_TABLE)))
  {
    table->file->print_error(error,MYF(0));	/* purecov: inspected */
    table->db_stat=0;
    goto err;
  }
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  statistic_increment(created_tmp_disk_tables, &LOCK_status);
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  table->db_record_offset=1;
  DBUG_RETURN(0);
 err:
  DBUG_RETURN(1);
}


void
free_tmp_table(THD *thd, TABLE *entry)
{
  const char *save_proc_info;
  DBUG_ENTER("free_tmp_table");
  DBUG_PRINT("enter",("table: %s",entry->table_name));

  save_proc_info=thd->proc_info;
  thd->proc_info="removing tmp table";
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  free_blobs(entry);
5867
  if (entry->file)
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  {
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    if (entry->db_stat)
    {
      (void) entry->file->close();
    }
    /*
      We can't call ha_delete_table here as the table may created in mixed case
      here and we have to ensure that delete_table gets the table name in
      the original case.
    */
    if (!(test_flags & TEST_KEEP_TMP_TABLES) || entry->db_type == DB_TYPE_HEAP)
      entry->file->delete_table(entry->real_name);
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    delete entry->file;
  }
5882

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  /* free blobs */
  for (Field **ptr=entry->field ; *ptr ; ptr++)
5885
    (*ptr)->free();
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  my_free((gptr) entry->record[0],MYF(0));
  free_io_cache(entry);
5888

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  if (entry->temp_pool_slot != MY_BIT_NONE)
    bitmap_clear_bit(&temp_pool, entry->temp_pool_slot);
5891

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  my_free((gptr) entry,MYF(0));
  thd->proc_info=save_proc_info;

  DBUG_VOID_RETURN;
}

/*
* If a HEAP table gets full, create a MyISAM table and copy all rows to this
*/

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bool create_myisam_from_heap(THD *thd, TABLE *table, TMP_TABLE_PARAM *param,
			     int error, bool ignore_last_dupp_key_error)
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{
  TABLE new_table;
  const char *save_proc_info;
  int write_err;
  DBUG_ENTER("create_myisam_from_heap");

  if (table->db_type != DB_TYPE_HEAP || error != HA_ERR_RECORD_FILE_FULL)
  {
    table->file->print_error(error,MYF(0));
    DBUG_RETURN(1);
  }
  new_table= *table;
  new_table.db_type=DB_TYPE_MYISAM;
  if (!(new_table.file=get_new_handler(&new_table,DB_TYPE_MYISAM)))
    DBUG_RETURN(1);				// End of memory

  save_proc_info=thd->proc_info;
  thd->proc_info="converting HEAP to MyISAM";

  if (create_myisam_tmp_table(&new_table,param,
5924
			      thd->lex->select_lex.options | thd->options))
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    goto err2;
  if (open_tmp_table(&new_table))
    goto err1;
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  if (table->file->indexes_are_disabled())
    new_table.file->disable_indexes(HA_KEY_SWITCH_ALL);
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  table->file->ha_index_or_rnd_end();
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  table->file->ha_rnd_init(1);
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  if (table->no_rows)
  {
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    new_table.file->extra(HA_EXTRA_NO_ROWS);
    new_table.no_rows=1;
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  }

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#ifdef TO_BE_DONE_LATER_IN_4_1
  /*
    To use start_bulk_insert() (which is new in 4.1) we need to find
    all places where a corresponding end_bulk_insert() should be put.
  */
  table->file->info(HA_STATUS_VARIABLE); /* update table->file->records */
  new_table.file->start_bulk_insert(table->file->records);
#else
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  /* HA_EXTRA_WRITE_CACHE can stay until close, no need to disable it */
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  new_table.file->extra(HA_EXTRA_WRITE_CACHE);
#endif

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  /* copy all old rows */
  while (!table->file->rnd_next(new_table.record[1]))
  {
    if ((write_err=new_table.file->write_row(new_table.record[1])))
      goto err;
  }
  /* copy row that filled HEAP table */
  if ((write_err=new_table.file->write_row(table->record[0])))
  {
    if (write_err != HA_ERR_FOUND_DUPP_KEY &&
	write_err != HA_ERR_FOUND_DUPP_UNIQUE || !ignore_last_dupp_key_error)
    goto err;
  }

  /* remove heap table and change to use myisam table */
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  (void) table->file->ha_rnd_end();
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  (void) table->file->close();
  (void) table->file->delete_table(table->real_name);
  delete table->file;
  table->file=0;
  *table =new_table;
  table->file->change_table_ptr(table);
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  thd->proc_info= (!strcmp(save_proc_info,"Copying to tmp table") ?
		   "Copying to tmp table on disk" : save_proc_info);
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  DBUG_RETURN(0);

 err:
  DBUG_PRINT("error",("Got error: %d",write_err));
  table->file->print_error(error,MYF(0));	// Give table is full error
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  (void) table->file->ha_rnd_end();
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  (void) new_table.file->close();
 err1:
  new_table.file->delete_table(new_table.real_name);
  delete new_table.file;
 err2:
  thd->proc_info=save_proc_info;
  DBUG_RETURN(1);
}


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/****************************************************************************
  Make a join of all tables and write it on socket or to table
  Return:  0 if ok
           1 if error is sent
          -1 if error should be sent
****************************************************************************/
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static int
do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
{
6000
  int error= 0;
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  JOIN_TAB *join_tab;
  int (*end_select)(JOIN *, struct st_join_table *,bool);
  DBUG_ENTER("do_select");
6004
  List<Item> *columns_list= procedure ? &join->procedure_fields_list : fields;
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  join->procedure=procedure;
  /*
6007
    Tell the client how many fields there are in a row
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  */
  if (!table)
6010
    join->result->send_fields(*columns_list, 1);
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  else
  {
    VOID(table->file->extra(HA_EXTRA_WRITE_CACHE));
    empty_record(table);
  }
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  join->tmp_table= table;			/* Save for easy recursion */
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  join->fields= fields;

  /* Set up select_end */
  if (table)
  {
    if (table->group && join->tmp_table_param.sum_func_count)
    {
      if (table->keys)
      {
6026
	DBUG_PRINT("info",("Using end_update"));
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	end_select=end_update;
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        if (!table->file->inited)
          table->file->ha_index_init(0);
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      }
      else
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      {
	DBUG_PRINT("info",("Using end_unique_update"));
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	end_select=end_unique_update;
6035
      }
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    }
    else if (join->sort_and_group)
    {
      DBUG_PRINT("info",("Using end_write_group"));
      end_select=end_write_group;
    }
    else
    {
      DBUG_PRINT("info",("Using end_write"));
      end_select=end_write;
    }
  }
  else
  {
    if (join->sort_and_group || (join->procedure &&
				 join->procedure->flags & PROC_GROUP))
      end_select=end_send_group;
    else
      end_select=end_send;
  }
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  if (join->tables)
  {
    join->join_tab[join->tables-1].next_select=end_select;
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6060 6061
    join_tab=join->join_tab+join->const_tables;
  }
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  join->send_records=0;
  if (join->tables == join->const_tables)
  {
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    /*
      HAVING will be chcked after processing aggregate functions,
      But WHERE should checkd here (we alredy have read tables)
    */
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    if (!join->conds || join->conds->val_int())
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    {
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      if (!(error=(*end_select)(join,join_tab,0)) || error == -3)
	error=(*end_select)(join,join_tab,1);
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    }
6074
    else if (join->send_row_on_empty_set())
6075
      error= join->result->send_data(*columns_list);
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  }
  else
  {
6079
    DBUG_ASSERT(join_tab);
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    error= sub_select(join,join_tab,0);
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    if (error >= 0)
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      error= sub_select(join,join_tab,1);
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    if (error == -3)
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      error= 0;					/* select_limit used */
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  }
6086

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  if (error >= 0)
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  {
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    error=0;
    if (!table)					// If sending data to client
6091
    {
6092
      /*
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	The following will unlock all cursors if the command wasn't an
	update command
6095
      */
6096
      join->join_free(0);				// Unlock all cursors
6097
      if (join->result->send_eof())
6098
	error= 1;				// Don't send error
6099
    }
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    DBUG_PRINT("info",("%ld records output",join->send_records));
  }
  if (table)
  {
6104
    int tmp, new_errno= 0;
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    if ((tmp=table->file->extra(HA_EXTRA_NO_CACHE)))
    {
6107
      DBUG_PRINT("error",("extra(HA_EXTRA_NO_CACHE) failed"));
6108
      new_errno= tmp;
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    }
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    if ((tmp=table->file->ha_index_or_rnd_end()))
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    {
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      DBUG_PRINT("error",("ha_index_or_rnd_end() failed"));
6113
      new_errno= tmp;
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    }
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    if (new_errno)
      table->file->print_error(new_errno,MYF(0));
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  }
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#ifndef DBUG_OFF
  if (error)
  {
    DBUG_PRINT("error",("Error: do_select() failed"));
  }
#endif
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  DBUG_RETURN(join->thd->net.report_error ? -1 : error);
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}


static int
sub_select_cache(JOIN *join,JOIN_TAB *join_tab,bool end_of_records)
{
  int error;

  if (end_of_records)
  {
    if ((error=flush_cached_records(join,join_tab,FALSE)) < 0)
      return error; /* purecov: inspected */
    return sub_select(join,join_tab,end_of_records);
  }
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  if (join->thd->killed)		// If aborted by user
  {
    my_error(ER_SERVER_SHUTDOWN,MYF(0)); /* purecov: inspected */
    return -2;				 /* purecov: inspected */
  }
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  if (join_tab->use_quick != 2 || test_if_quick_select(join_tab) <= 0)
  {
    if (!store_record_in_cache(&join_tab->cache))
      return 0;					// There is more room in cache
    return flush_cached_records(join,join_tab,FALSE);
  }
  if ((error=flush_cached_records(join,join_tab,TRUE)) < 0)
    return error; /* purecov: inspected */
  return sub_select(join,join_tab,end_of_records); /* Use ordinary select */
}


static int
sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records)
{

  join_tab->table->null_row=0;
  if (end_of_records)
    return (*join_tab->next_select)(join,join_tab+1,end_of_records);

  /* Cache variables for faster loop */
  int error;
  bool found=0;
  COND *on_expr=join_tab->on_expr, *select_cond=join_tab->select_cond;
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  my_bool *report_error= &(join->thd->net.report_error);
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  if (!(error=(*join_tab->read_first_record)(join_tab)))
  {
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    bool not_exists_optimize= join_tab->table->reginfo.not_exists_optimize;
    bool not_used_in_distinct=join_tab->not_used_in_distinct;
    ha_rows found_records=join->found_records;
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    READ_RECORD *info= &join_tab->read_record;

6177
    join->thd->row_count= 0;
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    do
    {
      if (join->thd->killed)			// Aborted by user
      {
	my_error(ER_SERVER_SHUTDOWN,MYF(0));	/* purecov: inspected */
	return -2;				/* purecov: inspected */
      }
6185
      join->examined_rows++;
6186
      join->thd->row_count++;
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      if (!on_expr || on_expr->val_int())
      {
	found=1;
	if (not_exists_optimize)
	  break;			// Searching after not null columns
	if (!select_cond || select_cond->val_int())
	{
6194
	  if ((error=(*join_tab->next_select)(join,join_tab+1,0)) < 0)
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	    return error;
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	  /*
	    Test if this was a SELECT DISTINCT query on a table that
	    was not in the field list;  In this case we can abort if
	    we found a row, as no new rows can be added to the result.
	  */
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	  if (not_used_in_distinct && found_records != join->found_records)
	    return 0;
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	}
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	else
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        {
          /* 
            This row failed selection, release lock on it.
            XXX: There is no table handler in MySQL which makes use of this
            call. It's kept from Gemini times. A lot of new code was added
            recently (i. e. subselects) without having it in mind.
          */
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	  info->file->unlock_row();
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        }
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      }
6215
    } while (!(error=info->read_record(info)) && !(*report_error));
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  }
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  if (error > 0 || (*report_error))				// Fatal error
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    return -1;

  if (!found && on_expr)
  {						// OUTER JOIN
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    restore_record(join_tab->table,default_values);		// Make empty record
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    mark_as_null_row(join_tab->table);		// For group by without error
    if (!select_cond || select_cond->val_int())
    {
6226
      if ((error=(*join_tab->next_select)(join,join_tab+1,0)) < 0)
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	return error;				/* purecov: inspected */
    }
  }
  return 0;
}


static int
6235
flush_cached_records(JOIN *join,JOIN_TAB *join_tab,bool skip_last)
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{
  int error;
  READ_RECORD *info;

  if (!join_tab->cache.records)
    return 0;				/* Nothing to do */
6242
  if (skip_last)
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    (void) store_record_in_cache(&join_tab->cache); // Must save this for later
  if (join_tab->use_quick == 2)
  {
    if (join_tab->select->quick)
    {					/* Used quick select last. reset it */
      delete join_tab->select->quick;
      join_tab->select->quick=0;
    }
  }
 /* read through all records */
  if ((error=join_init_read_record(join_tab)))
  {
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    reset_cache_write(&join_tab->cache);
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    return -error;			/* No records or error */
  }

  for (JOIN_TAB *tmp=join->join_tab; tmp != join_tab ; tmp++)
  {
    tmp->status=tmp->table->status;
    tmp->table->status=0;
  }

  info= &join_tab->read_record;
  do
  {
    if (join->thd->killed)
    {
      my_error(ER_SERVER_SHUTDOWN,MYF(0)); /* purecov: inspected */
      return -2;				// Aborted by user /* purecov: inspected */
    }
    SQL_SELECT *select=join_tab->select;
    if (!error && (!join_tab->cache.select ||
6275
		   !join_tab->cache.select->skip_record()))
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    {
      uint i;
6278
      reset_cache_read(&join_tab->cache);
6279
      for (i=(join_tab->cache.records- (skip_last ? 1 : 0)) ; i-- > 0 ;)
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      {
	read_cached_record(join_tab);
6282
	if (!select || !select->skip_record())
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	  if ((error=(join_tab->next_select)(join,join_tab+1,0)) < 0)
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          {
            reset_cache_write(&join_tab->cache);
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	    return error; /* purecov: inspected */
6287
          }
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      }
    }
  } while (!(error=info->read_record(info)));

6292
  if (skip_last)
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    read_cached_record(join_tab);		// Restore current record
6294
  reset_cache_write(&join_tab->cache);
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  if (error > 0)				// Fatal error
    return -1;					/* purecov: inspected */
  for (JOIN_TAB *tmp2=join->join_tab; tmp2 != join_tab ; tmp2++)
    tmp2->table->status=tmp2->status;
  return 0;
}


/*****************************************************************************
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  The different ways to read a record
  Returns -1 if row was not found, 0 if row was found and 1 on errors
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*****************************************************************************/
6307 6308 6309

/* Help function when we get some an error from the table handler */

6310
int report_error(TABLE *table, int error)
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{
  if (error == HA_ERR_END_OF_FILE || error == HA_ERR_KEY_NOT_FOUND)
  {
    table->status= STATUS_GARBAGE;
    return -1;					// key not found; ok
  }
  /*
    Locking reads can legally return also these errors, do not
    print them to the .err log
  */
  if (error != HA_ERR_LOCK_DEADLOCK && error != HA_ERR_LOCK_WAIT_TIMEOUT)
    sql_print_error("Got error %d when reading table '%s'",
		    error, table->path);
  table->file->print_error(error,MYF(0));
  return 1;
}


6329
int safe_index_read(JOIN_TAB *tab)
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{
  int error;
  TABLE *table= tab->table;
  if ((error=table->file->index_read(table->record[0],
				     tab->ref.key_buff,
				     tab->ref.key_length, HA_READ_KEY_EXACT)))
    return report_error(table, error);
  return 0;
}


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static int
6342
join_read_const_table(JOIN_TAB *tab, POSITION *pos)
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{
  int error;
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  DBUG_ENTER("join_read_const_table");
  TABLE *table=tab->table;
  table->const_table=1;
  table->null_row=0;
  table->status=STATUS_NO_RECORD;
  
  if (tab->type == JT_SYSTEM)
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  {
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    if ((error=join_read_system(tab)))
    {						// Info for DESCRIBE
      tab->info="const row not found";
      /* Mark for EXPLAIN that the row was not found */
      pos->records_read=0.0;
      if (!table->outer_join || error > 0)
	DBUG_RETURN(error);
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    }
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  }
  else
  {
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    if (!table->key_read && table->used_keys.is_set(tab->ref.key) &&
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	!table->no_keyread &&
        (int) table->reginfo.lock_type <= (int) TL_READ_HIGH_PRIORITY)
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    {
      table->key_read=1;
      table->file->extra(HA_EXTRA_KEYREAD);
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      tab->index= tab->ref.key;
6371
    }
6372
    if ((error=join_read_const(tab)))
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    {
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      tab->info="unique row not found";
      /* Mark for EXPLAIN that the row was not found */
      pos->records_read=0.0;
      if (!table->outer_join || error > 0)
	DBUG_RETURN(error);
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    }
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    if (table->key_read)
    {
      table->key_read=0;
      table->file->extra(HA_EXTRA_NO_KEYREAD);
    }
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  }
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  if (tab->on_expr && !table->null_row)
  {
    if ((table->null_row= test(tab->on_expr->val_int() == 0)))
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      mark_as_null_row(table);  
  }
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  if (!table->null_row)
    table->maybe_null=0;
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  DBUG_RETURN(0);
}


static int
join_read_system(JOIN_TAB *tab)
{
  TABLE *table= tab->table;
  int error;
  if (table->status & STATUS_GARBAGE)		// If first read
  {
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    if ((error=table->file->read_first_row(table->record[0],
					   table->primary_key)))
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    {
      if (error != HA_ERR_END_OF_FILE)
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	return report_error(table, error);
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      mark_as_null_row(tab->table);
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      empty_record(table);			// Make empty record
      return -1;
    }
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    store_record(table,record[1]);
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  }
  else if (!table->status)			// Only happens with left join
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    restore_record(table,record[1]);			// restore old record
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  table->null_row=0;
  return table->status ? -1 : 0;
}


static int
join_read_const(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;
  if (table->status & STATUS_GARBAGE)		// If first read
  {
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    if (cp_buffer_from_ref(tab->join->thd, &tab->ref))
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      error=HA_ERR_KEY_NOT_FOUND;
    else
    {
      error=table->file->index_read_idx(table->record[0],tab->ref.key,
					(byte*) tab->ref.key_buff,
					tab->ref.key_length,HA_READ_KEY_EXACT);
    }
    if (error)
    {
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      mark_as_null_row(tab->table);
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      empty_record(table);
      if (error != HA_ERR_KEY_NOT_FOUND)
6442
	return report_error(table, error);
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      return -1;
    }
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    store_record(table,record[1]);
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  }
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  else if (!(table->status & ~STATUS_NULL_ROW))	// Only happens with left join
  {
    table->status=0;
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    restore_record(table,record[1]);			// restore old record
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  }
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  table->null_row=0;
  return table->status ? -1 : 0;
}


static int
join_read_key(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;

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  if (!table->file->inited)
    table->file->ha_index_init(tab->ref.key);
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  if (cmp_buffer_with_ref(tab) ||
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      (table->status & (STATUS_GARBAGE | STATUS_NO_PARENT | STATUS_NULL_ROW)))
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  {
    if (tab->ref.key_err)
    {
      table->status=STATUS_NOT_FOUND;
      return -1;
    }
    error=table->file->index_read(table->record[0],
				  tab->ref.key_buff,
				  tab->ref.key_length,HA_READ_KEY_EXACT);
    if (error && error != HA_ERR_KEY_NOT_FOUND)
6477
      return report_error(table, error);
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  }
6479
  table->null_row=0;
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  return table->status ? -1 : 0;
}


static int
join_read_always_key(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;

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  for (uint i= 0 ; i < tab->ref.key_parts ; i++)
  {
    if ((tab->ref.null_rejecting & 1 << i) && tab->ref.items[i]->is_null())
        return -1;
  } 
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  if (!table->file->inited)
    table->file->ha_index_init(tab->ref.key);
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  if (cp_buffer_from_ref(tab->join->thd, &tab->ref))
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    return -1;
  if ((error=table->file->index_read(table->record[0],
				     tab->ref.key_buff,
				     tab->ref.key_length,HA_READ_KEY_EXACT)))
  {
    if (error != HA_ERR_KEY_NOT_FOUND)
6504
      return report_error(table, error);
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    return -1; /* purecov: inspected */
  }
  return 0;
}

6510

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/*
  This function is used when optimizing away ORDER BY in 
  SELECT * FROM t1 WHERE a=1 ORDER BY a DESC,b DESC
*/
  
static int
join_read_last_key(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;

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  if (!table->file->inited)
    table->file->ha_index_init(tab->ref.key);
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  if (cp_buffer_from_ref(tab->join->thd, &tab->ref))
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    return -1;
  if ((error=table->file->index_read_last(table->record[0],
					  tab->ref.key_buff,
					  tab->ref.key_length)))
  {
    if (error != HA_ERR_KEY_NOT_FOUND)
6531
      return report_error(table, error);
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    return -1; /* purecov: inspected */
  }
  return 0;
}

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	/* ARGSUSED */
static int
join_no_more_records(READ_RECORD *info __attribute__((unused)))
{
  return -1;
}


static int
6547
join_read_next_same(READ_RECORD *info)
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{
  int error;
  TABLE *table= info->table;
  JOIN_TAB *tab=table->reginfo.join_tab;

  if ((error=table->file->index_next_same(table->record[0],
					  tab->ref.key_buff,
					  tab->ref.key_length)))
  {
    if (error != HA_ERR_END_OF_FILE)
6558
      return report_error(table, error);
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    table->status= STATUS_GARBAGE;
    return -1;
  }
  return 0;
}

6565

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static int
join_read_prev_same(READ_RECORD *info)
{
  int error;
  TABLE *table= info->table;
  JOIN_TAB *tab=table->reginfo.join_tab;

  if ((error=table->file->index_prev(table->record[0])))
6574
    return report_error(table, error);
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  if (key_cmp_if_same(table, tab->ref.key_buff, tab->ref.key,
                      tab->ref.key_length))
6577 6578
  {
    table->status=STATUS_NOT_FOUND;
6579
    error= -1;
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  }
  return error;
}

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static int
join_init_quick_read_record(JOIN_TAB *tab)
{
  if (test_if_quick_select(tab) == -1)
    return -1;					/* No possible records */
  return join_init_read_record(tab);
}


static int
test_if_quick_select(JOIN_TAB *tab)
{
  delete tab->select->quick;
  tab->select->quick=0;
6599
  return tab->select->test_quick_select(tab->join->thd, tab->keys,
6600
					(table_map) 0, HA_POS_ERROR, 0);
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}


static int
join_init_read_record(JOIN_TAB *tab)
{
  if (tab->select && tab->select->quick)
    tab->select->quick->reset();
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  init_read_record(&tab->read_record, tab->join->thd, tab->table,
		   tab->select,1,1);
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  return (*tab->read_record.read_record)(&tab->read_record);
}

6614

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static int
6616
join_read_first(JOIN_TAB *tab)
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{
  int error;
  TABLE *table=tab->table;
6620
  if (!table->key_read && table->used_keys.is_set(tab->index) &&
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      !table->no_keyread)
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  {
    table->key_read=1;
    table->file->extra(HA_EXTRA_KEYREAD);
  }
  tab->table->status=0;
6627
  tab->read_record.read_record=join_read_next;
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  tab->read_record.table=table;
  tab->read_record.file=table->file;
  tab->read_record.index=tab->index;
  tab->read_record.record=table->record[0];
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  if (!table->file->inited)
    table->file->ha_index_init(tab->index);
6634
  if ((error=tab->table->file->index_first(tab->table->record[0])))
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  {
    if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
6637
      report_error(table, error);
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    return -1;
  }
  return 0;
}

6643

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static int
6645
join_read_next(READ_RECORD *info)
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{
6647 6648 6649
  int error;
  if ((error=info->file->index_next(info->record)))
    return report_error(info->table, error);
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  return 0;
}

6653

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static int
6655
join_read_last(JOIN_TAB *tab)
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{
  TABLE *table=tab->table;
  int error;
6659
  if (!table->key_read && table->used_keys.is_set(tab->index) &&
6660
      !table->no_keyread)
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  {
    table->key_read=1;
    table->file->extra(HA_EXTRA_KEYREAD);
  }
  tab->table->status=0;
6666
  tab->read_record.read_record=join_read_prev;
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  tab->read_record.table=table;
  tab->read_record.file=table->file;
  tab->read_record.index=tab->index;
  tab->read_record.record=table->record[0];
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  if (!table->file->inited)
    table->file->ha_index_init(tab->index);
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  if ((error= tab->table->file->index_last(tab->table->record[0])))
    return report_error(table, error);
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  return 0;
}

6678

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static int
6680
join_read_prev(READ_RECORD *info)
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{
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  int error;
  if ((error= info->file->index_prev(info->record)))
    return report_error(info->table, error);
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  return 0;
}

6688

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static int
join_ft_read_first(JOIN_TAB *tab)
{
  int error;
  TABLE *table= tab->table;

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  if (!table->file->inited)
    table->file->ha_index_init(tab->ref.key);
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#if NOT_USED_YET
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  if (cp_buffer_from_ref(tab->join->thd, &tab->ref)) // as ft-key doesn't use store_key's
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    return -1;                             // see also FT_SELECT::init()
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#endif
6701
  table->file->ft_init();
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6703 6704
  if ((error= table->file->ft_read(table->record[0])))
    return report_error(table, error);
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  return 0;
}

static int
join_ft_read_next(READ_RECORD *info)
{
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  int error;
  if ((error= info->file->ft_read(info->table->record[0])))
    return report_error(info->table, error);
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  return 0;
}


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/*
  Reading of key with key reference and one part that may be NULL
*/

static int
join_read_always_key_or_null(JOIN_TAB *tab)
{
  int res;

  /* First read according to key which is NOT NULL */
6728
  *tab->ref.null_ref_key= 0;			// Clear null byte
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  if ((res= join_read_always_key(tab)) >= 0)
    return res;

  /* Then read key with null value */
6733
  *tab->ref.null_ref_key= 1;			// Set null byte
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  return safe_index_read(tab);
}


static int
join_read_next_same_or_null(READ_RECORD *info)
{
  int error;
  if ((error= join_read_next_same(info)) >= 0)
    return error;
  JOIN_TAB *tab= info->table->reginfo.join_tab;

  /* Test if we have already done a read after null key */
6747
  if (*tab->ref.null_ref_key)
6748
    return -1;					// All keys read
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  *tab->ref.null_ref_key= 1;			// Set null byte
  return safe_index_read(tab);			// then read null keys
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}


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/*****************************************************************************
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  The different end of select functions
  These functions returns < 0 when end is reached, 0 on ok and > 0 if a
  fatal error (like table corruption) was detected
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*****************************************************************************/

6760
/* ARGSUSED */
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static int
end_send(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
	 bool end_of_records)
{
  DBUG_ENTER("end_send");
  if (!end_of_records)
  {
    int error;
6769
    if (join->having && join->having->val_int() == 0)
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      DBUG_RETURN(0);				// Didn't match having
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    error=0;
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    if (join->procedure)
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      error=join->procedure->send_row(join->procedure_fields_list);
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    else if (join->do_send_rows)
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      error=join->result->send_data(*join->fields);
    if (error)
      DBUG_RETURN(-1); /* purecov: inspected */
6778
    if (++join->send_records >= join->unit->select_limit_cnt &&
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	join->do_send_rows)
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    {
      if (join->select_options & OPTION_FOUND_ROWS)
      {
6783
	JOIN_TAB *jt=join->join_tab;
6784
	if ((join->tables == 1) && !join->tmp_table && !join->sort_and_group
6785
	    && !join->send_group_parts && !join->having && !jt->select_cond &&
6786
	    !(jt->select && jt->select->quick) &&
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	    !(jt->table->file->table_flags() & HA_NOT_EXACT_COUNT) &&
            (jt->ref.key < 0))
6789
	{
6790
	  /* Join over all rows in table;  Return number of found rows */
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	  TABLE *table=jt->table;

6793
	  join->select_options ^= OPTION_FOUND_ROWS;
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	  if (table->sort.record_pointers ||
	      (table->sort.io_cache && my_b_inited(table->sort.io_cache)))
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	  {
	    /* Using filesort */
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	    join->send_records= table->sort.found_records;
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	  }
	  else
	  {
	    table->file->info(HA_STATUS_VARIABLE);
	    join->send_records = table->file->records;
	  }
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	}
	else 
	{
6808
	  join->do_send_rows= 0;
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	  if (join->unit->fake_select_lex)
	    join->unit->fake_select_lex->select_limit= HA_POS_ERROR;
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	  DBUG_RETURN(0);
	}
6813
      }
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      DBUG_RETURN(-3);				// Abort nicely
6815
    }
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  }
  else
  {
    if (join->procedure && join->procedure->end_of_records())
      DBUG_RETURN(-1);
  }
  DBUG_RETURN(0);
}


	/* ARGSUSED */
static int
end_send_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
	       bool end_of_records)
{
  int idx= -1;
  DBUG_ENTER("end_send_group");

  if (!join->first_record || end_of_records ||
      (idx=test_if_group_changed(join->group_fields)) >= 0)
  {
    if (join->first_record || (end_of_records && !join->group))
    {
      if (join->procedure)
	join->procedure->end_group();
      if (idx < (int) join->send_group_parts)
      {
6843
	int error=0;
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	if (join->procedure)
	{
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	  if (join->having && join->having->val_int() == 0)
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	    error= -1;				// Didn't satisfy having
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 	  else
	  {
	    if (join->do_send_rows)
	      error=join->procedure->send_row(*join->fields) ? 1 : 0;
	    join->send_records++;
	  }
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	  if (end_of_records && join->procedure->end_of_records())
	    error= 1;				// Fatal error
	}
	else
	{
	  if (!join->first_record)
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	  {
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            List_iterator_fast<Item> it(*join->fields);
            Item *item;
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	    /* No matching rows for group function */
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	    join->clear();
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            while ((item= it++))
              item->no_rows_in_result();
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	  }
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	  if (join->having && join->having->val_int() == 0)
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	    error= -1;				// Didn't satisfy having
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	  else
	  {
	    if (join->do_send_rows)
	      error=join->result->send_data(*join->fields) ? 1 : 0;
	    join->send_records++;
	  }
	  if (join->rollup.state != ROLLUP::STATE_NONE && error <= 0)
	  {
	    if (join->rollup_send_data((uint) (idx+1)))
	      error= 1;
	  }
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	}
	if (error > 0)
	  DBUG_RETURN(-1);			/* purecov: inspected */
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	if (end_of_records)
	  DBUG_RETURN(0);
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	if (join->send_records >= join->unit->select_limit_cnt &&
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	    join->do_send_rows)
	{
	  if (!(join->select_options & OPTION_FOUND_ROWS))
	    DBUG_RETURN(-3);				// Abort nicely
	  join->do_send_rows=0;
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	  join->unit->select_limit_cnt = HA_POS_ERROR;
6894
        }
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      }
    }
    else
    {
      if (end_of_records)
	DBUG_RETURN(0);
      join->first_record=1;
      VOID(test_if_group_changed(join->group_fields));
    }
    if (idx < (int) join->send_group_parts)
    {
      copy_fields(&join->tmp_table_param);
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      if (init_sum_functions(join->sum_funcs, join->sum_funcs_end[idx+1]))
	DBUG_RETURN(-1);
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      if (join->procedure)
	join->procedure->add();
      DBUG_RETURN(0);
    }
  }
  if (update_sum_func(join->sum_funcs))
    DBUG_RETURN(-1);
  if (join->procedure)
    join->procedure->add();
  DBUG_RETURN(0);
}


	/* ARGSUSED */
static int
end_write(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
	  bool end_of_records)
{
  TABLE *table=join->tmp_table;
  int error;
  DBUG_ENTER("end_write");

  if (join->thd->killed)			// Aborted by user
  {
    my_error(ER_SERVER_SHUTDOWN,MYF(0));	/* purecov: inspected */
    DBUG_RETURN(-2);				/* purecov: inspected */
  }
  if (!end_of_records)
  {
    copy_fields(&join->tmp_table_param);
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    copy_funcs(join->tmp_table_param.items_to_copy);
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#ifdef TO_BE_DELETED
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    if (!table->uniques)			// If not unique handling
    {
      /* Copy null values from group to row */
      ORDER   *group;
      for (group=table->group ; group ; group=group->next)
      {
	Item *item= *group->item;
	if (item->maybe_null)
	{
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	  Field *field=item->get_tmp_table_field();
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	  field->ptr[-1]= (byte) (field->is_null() ? 1 : 0);
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	}
      }
    }
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#endif
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    if (!join->having || join->having->val_int())
    {
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      join->found_records++;
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      if ((error=table->file->write_row(table->record[0])))
      {
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	if (error == HA_ERR_FOUND_DUPP_KEY ||
	    error == HA_ERR_FOUND_DUPP_UNIQUE)
	  goto end;
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	if (create_myisam_from_heap(join->thd, table, &join->tmp_table_param,
				    error,1))
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	  DBUG_RETURN(-1);			// Not a table_is_full error
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	table->uniques=0;			// To ensure rows are the same
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      }
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      if (++join->send_records >= join->tmp_table_param.end_write_records &&
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	  join->do_send_rows)
      {
	if (!(join->select_options & OPTION_FOUND_ROWS))
	  DBUG_RETURN(-3);
	join->do_send_rows=0;
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	join->unit->select_limit_cnt = HA_POS_ERROR;
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	DBUG_RETURN(0);
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      }
    }
  }
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end:
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  DBUG_RETURN(0);
}

/* Group by searching after group record and updating it if possible */
/* ARGSUSED */

static int
end_update(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
	   bool end_of_records)
{
  TABLE *table=join->tmp_table;
  ORDER   *group;
  int	  error;
  DBUG_ENTER("end_update");

  if (end_of_records)
    DBUG_RETURN(0);
  if (join->thd->killed)			// Aborted by user
  {
    my_error(ER_SERVER_SHUTDOWN,MYF(0));	/* purecov: inspected */
    DBUG_RETURN(-2);				/* purecov: inspected */
  }

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  join->found_records++;
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  copy_fields(&join->tmp_table_param);		// Groups are copied twice.
  /* Make a key of group index */
  for (group=table->group ; group ; group=group->next)
  {
    Item *item= *group->item;
    item->save_org_in_field(group->field);
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#ifdef EMBEDDED_LIBRARY
    join->thd->net.last_errno= 0;
#endif
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    /* Store in the used key if the field was 0 */
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    if (item->maybe_null)
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      group->buff[-1]=item->null_value ? 1 : 0;
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  }
  if (!table->file->index_read(table->record[1],
			       join->tmp_table_param.group_buff,0,
			       HA_READ_KEY_EXACT))
  {						/* Update old record */
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    restore_record(table,record[1]);
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    update_tmptable_sum_func(join->sum_funcs,table);
    if ((error=table->file->update_row(table->record[1],
				       table->record[0])))
    {
      table->file->print_error(error,MYF(0));	/* purecov: inspected */
      DBUG_RETURN(-1);				/* purecov: inspected */
    }
    DBUG_RETURN(0);
  }

  /* The null bits are already set */
  KEY_PART_INFO *key_part;
  for (group=table->group,key_part=table->key_info[0].key_part;
       group ;
       group=group->next,key_part++)
    memcpy(table->record[0]+key_part->offset, group->buff, key_part->length);

  init_tmptable_sum_functions(join->sum_funcs);
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  copy_funcs(join->tmp_table_param.items_to_copy);
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  if ((error=table->file->write_row(table->record[0])))
  {
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    if (create_myisam_from_heap(join->thd, table, &join->tmp_table_param,
				error, 0))
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      DBUG_RETURN(-1);				// Not a table_is_full error
    /* Change method to update rows */
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    table->file->ha_index_init(0);
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    join->join_tab[join->tables-1].next_select=end_unique_update;
  }
  join->send_records++;
  DBUG_RETURN(0);
}

/* Like end_update, but this is done with unique constraints instead of keys */

static int
end_unique_update(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
		  bool end_of_records)
{
  TABLE *table=join->tmp_table;
  int	  error;
  DBUG_ENTER("end_unique_update");

  if (end_of_records)
    DBUG_RETURN(0);
  if (join->thd->killed)			// Aborted by user
  {
    my_error(ER_SERVER_SHUTDOWN,MYF(0));	/* purecov: inspected */
    DBUG_RETURN(-2);				/* purecov: inspected */
  }

  init_tmptable_sum_functions(join->sum_funcs);
  copy_fields(&join->tmp_table_param);		// Groups are copied twice.
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  copy_funcs(join->tmp_table_param.items_to_copy);
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  if (!(error=table->file->write_row(table->record[0])))
    join->send_records++;			// New group
  else
  {
    if ((int) table->file->get_dup_key(error) < 0)
    {
      table->file->print_error(error,MYF(0));	/* purecov: inspected */
      DBUG_RETURN(-1);				/* purecov: inspected */
    }
    if (table->file->rnd_pos(table->record[1],table->file->dupp_ref))
    {
      table->file->print_error(error,MYF(0));	/* purecov: inspected */
      DBUG_RETURN(-1);				/* purecov: inspected */
    }
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    restore_record(table,record[1]);
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    update_tmptable_sum_func(join->sum_funcs,table);
    if ((error=table->file->update_row(table->record[1],
				       table->record[0])))
    {
      table->file->print_error(error,MYF(0));	/* purecov: inspected */
      DBUG_RETURN(-1);				/* purecov: inspected */
    }
  }
  DBUG_RETURN(0);
}


	/* ARGSUSED */
static int
end_write_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
		bool end_of_records)
{
  TABLE *table=join->tmp_table;
  int	  error;
  int	  idx= -1;
  DBUG_ENTER("end_write_group");

  if (join->thd->killed)
  {						// Aborted by user
    my_error(ER_SERVER_SHUTDOWN,MYF(0));	/* purecov: inspected */
    DBUG_RETURN(-2);				/* purecov: inspected */
  }
  if (!join->first_record || end_of_records ||
      (idx=test_if_group_changed(join->group_fields)) >= 0)
  {
    if (join->first_record || (end_of_records && !join->group))
    {
      if (join->procedure)
	join->procedure->end_group();
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      int send_group_parts= join->send_group_parts;
      if (idx < send_group_parts)
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      {
	if (!join->first_record)
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	{
	  /* No matching rows for group function */
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	  join->clear();
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	}
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        copy_sum_funcs(join->sum_funcs,
                       join->sum_funcs_end[send_group_parts]);
	if (join->having && join->having->val_int() == 0)
          error= -1;
        else if ((error=table->file->write_row(table->record[0])))
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	{
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	  if (create_myisam_from_heap(join->thd, table,
				      &join->tmp_table_param,
				      error, 0))
	    DBUG_RETURN(-1);		       
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            /* 
              If table->file->write_row() was failed because of 'out of memory'
              and tmp table succesfully created, reset error.
             */
            error=0;
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        }
        if (join->rollup.state != ROLLUP::STATE_NONE && error <= 0)
	{
	  if (join->rollup_write_data((uint) (idx+1), table))
	    error= 1;
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	}
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	if (error > 0)
	  DBUG_RETURN(-1);	  
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	if (end_of_records)
	  DBUG_RETURN(0);
      }
    }
    else
    {
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      if (end_of_records)
	DBUG_RETURN(0);
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      join->first_record=1;
      VOID(test_if_group_changed(join->group_fields));
    }
    if (idx < (int) join->send_group_parts)
    {
      copy_fields(&join->tmp_table_param);
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      copy_funcs(join->tmp_table_param.items_to_copy);
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      if (init_sum_functions(join->sum_funcs, join->sum_funcs_end[idx+1]))
	DBUG_RETURN(-1);
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      if (join->procedure)
	join->procedure->add();
      DBUG_RETURN(0);
    }
  }
  if (update_sum_func(join->sum_funcs))
    DBUG_RETURN(-1);
  if (join->procedure)
    join->procedure->add();
  DBUG_RETURN(0);
}


/*****************************************************************************
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  Remove calculation with tables that aren't yet read. Remove also tests
  against fields that are read through key where the table is not a
  outer join table.
  We can't remove tests that are made against columns which are stored
  in sorted order.
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*****************************************************************************/

/* Return 1 if right_item is used removable reference key on left_item */

static bool test_if_ref(Item_field *left_item,Item *right_item)
{
  Field *field=left_item->field;
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  // No need to change const test. We also have to keep tests on LEFT JOIN
  if (!field->table->const_table && !field->table->maybe_null)
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  {
    Item *ref_item=part_of_refkey(field->table,field);
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    if (ref_item && ref_item->eq(right_item,1))
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    {
      if (right_item->type() == Item::FIELD_ITEM)
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	return (field->eq_def(((Item_field *) right_item)->field));
      if (right_item->const_item() && !(right_item->is_null()))
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      {
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	/*
	  We can remove binary fields and numerical fields except float,
	  as float comparison isn't 100 % secure
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	  We have to keep binary strings to be able to check for end spaces
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	*/
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	if (field->binary() &&
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	    field->real_type() != FIELD_TYPE_STRING &&
	    field->real_type() != FIELD_TYPE_VAR_STRING &&
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	    (field->type() != FIELD_TYPE_FLOAT || field->decimals() == 0))
	{
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	  return !store_val_in_field(field, right_item, CHECK_FIELD_WARN);
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	}
      }
    }
  }
  return 0;					// keep test
}


static COND *
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make_cond_for_table(COND *cond, table_map tables, table_map used_table)
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{
  if (used_table && !(cond->used_tables() & used_table))
    return (COND*) 0;				// Already checked
  if (cond->type() == Item::COND_ITEM)
  {
    if (((Item_cond*) cond)->functype() == Item_func::COND_AND_FUNC)
    {
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      /* Create new top level AND item */
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      Item_cond_and *new_cond=new Item_cond_and;
      if (!new_cond)
	return (COND*) 0;			// OOM /* purecov: inspected */
      List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
      Item *item;
      while ((item=li++))
      {
	Item *fix=make_cond_for_table(item,tables,used_table);
	if (fix)
	  new_cond->argument_list()->push_back(fix);
      }
      switch (new_cond->argument_list()->elements) {
      case 0:
	return (COND*) 0;			// Always true
      case 1:
	return new_cond->argument_list()->head();
      default:
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	/*
	  Item_cond_and do not need fix_fields for execution, its parameters
	  are fixed or do not need fix_fields, too
	*/
	new_cond->quick_fix_field();
	new_cond->used_tables_cache=
	  ((Item_cond_and*) cond)->used_tables_cache &
	  tables;
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	return new_cond;
      }
    }
    else
    {						// Or list
      Item_cond_or *new_cond=new Item_cond_or;
      if (!new_cond)
	return (COND*) 0;			// OOM /* purecov: inspected */
      List_iterator<Item> li(*((Item_cond*) cond)->argument_list());
      Item *item;
      while ((item=li++))
      {
	Item *fix=make_cond_for_table(item,tables,0L);
	if (!fix)
	  return (COND*) 0;			// Always true
	new_cond->argument_list()->push_back(fix);
      }
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      /*
	Item_cond_and do not need fix_fields for execution, its parameters
	are fixed or do not need fix_fields, too
      */
      new_cond->quick_fix_field();
      new_cond->used_tables_cache= ((Item_cond_or*) cond)->used_tables_cache;
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      new_cond->top_level_item();
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      return new_cond;
    }
  }

  /*
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    Because the following test takes a while and it can be done
    table_count times, we mark each item that we have examined with the result
    of the test
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  */

  if (cond->marker == 3 || (cond->used_tables() & ~tables))
    return (COND*) 0;				// Can't check this yet
  if (cond->marker == 2 || cond->eq_cmp_result() == Item::COND_OK)
    return cond;				// Not boolean op

  if (((Item_func*) cond)->functype() == Item_func::EQ_FUNC)
  {
    Item *left_item=	((Item_func*) cond)->arguments()[0];
    Item *right_item= ((Item_func*) cond)->arguments()[1];
    if (left_item->type() == Item::FIELD_ITEM &&
	test_if_ref((Item_field*) left_item,right_item))
    {
      cond->marker=3;			// Checked when read
      return (COND*) 0;
    }
    if (right_item->type() == Item::FIELD_ITEM &&
	test_if_ref((Item_field*) right_item,left_item))
    {
      cond->marker=3;			// Checked when read
      return (COND*) 0;
    }
  }
  cond->marker=2;
  return cond;
}

static Item *
part_of_refkey(TABLE *table,Field *field)
{
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  if (!table->reginfo.join_tab)
    return (Item*) 0;             // field from outer non-select (UPDATE,...)

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  uint ref_parts=table->reginfo.join_tab->ref.key_parts;
  if (ref_parts)
  {
    KEY_PART_INFO *key_part=
      table->key_info[table->reginfo.join_tab->ref.key].key_part;

    for (uint part=0 ; part < ref_parts ; part++,key_part++)
      if (field->eq(key_part->field) &&
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	  !(key_part->key_part_flag & HA_PART_KEY_SEG))
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	return table->reginfo.join_tab->ref.items[part];
  }
  return (Item*) 0;
}


/*****************************************************************************
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  Test if one can use the key to resolve ORDER BY
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  SYNOPSIS
    test_if_order_by_key()
    order		Sort order
    table		Table to sort
    idx			Index to check
    used_key_parts	Return value for used key parts.


  NOTES
    used_key_parts is set to correct key parts used if return value != 0
    (On other cases, used_key_part may be changed)

  RETURN
    1   key is ok.
    0   Key can't be used
    -1  Reverse key can be used
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*****************************************************************************/

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static int test_if_order_by_key(ORDER *order, TABLE *table, uint idx,
				uint *used_key_parts)
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{
  KEY_PART_INFO *key_part,*key_part_end;
  key_part=table->key_info[idx].key_part;
  key_part_end=key_part+table->key_info[idx].key_parts;
  key_part_map const_key_parts=table->const_key_parts[idx];
  int reverse=0;
7375
  DBUG_ENTER("test_if_order_by_key");
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  for (; order ; order=order->next, const_key_parts>>=1)
  {
    Field *field=((Item_field*) (*order->item))->field;
    int flag;

    /*
      Skip key parts that are constants in the WHERE clause.
      These are already skipped in the ORDER BY by const_expression_in_where()
    */
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    for (; const_key_parts & 1 ; const_key_parts>>= 1)
      key_part++; 

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    if (key_part == key_part_end || key_part->field != field)
7390
      DBUG_RETURN(0);
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    /* set flag to 1 if we can use read-next on key, else to -1 */
7393 7394
    flag= ((order->asc == !(key_part->key_part_flag & HA_REVERSE_SORT)) ?
           1 : -1);
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    if (reverse && flag != reverse)
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      DBUG_RETURN(0);
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    reverse=flag;				// Remember if reverse
    key_part++;
  }
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  *used_key_parts= (uint) (key_part - table->key_info[idx].key_part);
  if (reverse == -1 && !(table->file->index_flags(idx, *used_key_parts-1, 1) &
                         HA_READ_PREV))
    reverse= 0;                                 // Index can't be used
7404
  DBUG_RETURN(reverse);
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}

7407

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static uint find_shortest_key(TABLE *table, const key_map *usable_keys)
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{
  uint min_length= (uint) ~0;
  uint best= MAX_KEY;
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  if (!usable_keys->is_clear_all())
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  {
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    for (uint nr=0; nr < table->keys ; nr++)
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    {
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      if (usable_keys->is_set(nr))
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      {
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        if (table->key_info[nr].key_length < min_length)
        {
          min_length=table->key_info[nr].key_length;
          best=nr;
        }
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      }
    }
  }
  return best;
}

7429
/*
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  Test if a second key is the subkey of the first one.

7432 7433
  SYNOPSIS
    is_subkey()
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    key_part		First key parts
    ref_key_part	Second key parts
    ref_key_part_end	Last+1 part of the second key

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  NOTE
    Second key MUST be shorter than the first one.
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  RETURN
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    1	is a subkey
    0	no sub key
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*/

inline bool 
is_subkey(KEY_PART_INFO *key_part, KEY_PART_INFO *ref_key_part,
	  KEY_PART_INFO *ref_key_part_end)
{
  for (; ref_key_part < ref_key_part_end; key_part++, ref_key_part++)
    if (!key_part->field->eq(ref_key_part->field))
      return 0;
  return 1;
}

/*
7457 7458
  Test if we can use one of the 'usable_keys' instead of 'ref' key for sorting

7459 7460
  SYNOPSIS
    test_if_subkey()
7461 7462 7463
    ref			Number of key, used for WHERE clause
    usable_keys		Keys for testing

7464
  RETURN
7465 7466
    MAX_KEY			If we can't use other key
    the number of found key	Otherwise
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*/

static uint
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test_if_subkey(ORDER *order, TABLE *table, uint ref, uint ref_key_parts,
7471
	       const key_map *usable_keys)
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{
  uint nr;
  uint min_length= (uint) ~0;
  uint best= MAX_KEY;
  uint not_used;
  KEY_PART_INFO *ref_key_part= table->key_info[ref].key_part;
  KEY_PART_INFO *ref_key_part_end= ref_key_part + ref_key_parts;
7479

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  for (nr= 0 ; nr < table->keys ; nr++)
7481
  {
7482
    if (usable_keys->is_set(nr) &&
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	table->key_info[nr].key_length < min_length &&
	table->key_info[nr].key_parts >= ref_key_parts &&
	is_subkey(table->key_info[nr].key_part, ref_key_part,
		  ref_key_part_end) &&
	test_if_order_by_key(order, table, nr, &not_used))
    {
      min_length= table->key_info[nr].key_length;
      best= nr;
    }
  }
  return best;
}
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/*
  Check if GROUP BY/DISTINCT can be optimized away because the set is 
  already known to be distinct.
  
  SYNOPSIS
    list_contains_unique_index ()
    table                The table to operate on.
    find_func            function to iterate over the list and search
                         for a field
  
  DESCRIPTION
    Used in removing the GROUP BY/DISTINCT of the following types of
    statements:
      SELECT [DISTINCT] <unique_key_cols>... FROM <single_table_ref>
        [GROUP BY <unique_key_cols>,...]

    If (a,b,c is distinct)
      then <any combination of a,b,c>,{whatever} is also distinct

    This function checks if all the key parts of any of the unique keys
    of the table are referenced by a list : either the select list 
    through find_field_in_item_list or GROUP BY list through
    find_field_in_order_list.
    If the above holds then we can safely remove the GROUP BY/DISTINCT,
    as no result set can be more distinct than an unique key.
  
  RETURN VALUE
    1                    found
    0                    not found.
*/

static bool
list_contains_unique_index(TABLE *table,
                          bool (*find_func) (Field *, void *), void *data)
{
  for (uint keynr= 0; keynr < table->keys; keynr++)
  {
    if (keynr == table->primary_key ||
         (table->key_info[keynr].flags & HA_NOSAME))
    {
      KEY *keyinfo= table->key_info + keynr;
      KEY_PART_INFO *key_part, *key_part_end;

      for (key_part=keyinfo->key_part,
           key_part_end=key_part+ keyinfo->key_parts;
           key_part < key_part_end;
           key_part++)
      {
        if (!find_func(key_part->field, data))
          break;
      }
      if (key_part == key_part_end)
        return 1;
    }
  }
  return 0;
}


/*
  Helper function for list_contains_unique_index.
  Find a field reference in a list of ORDER structures.
  
  SYNOPSIS
    find_field_in_order_list ()
    field                The field to search for.
    data                 ORDER *.The list to search in
  
  DESCRIPTION
    Finds a direct reference of the Field in the list.
  
  RETURN VALUE
    1                    found
    0                    not found.
*/

static bool
find_field_in_order_list (Field *field, void *data)
{
  ORDER *group= (ORDER *) data;
  bool part_found= 0;
  for (ORDER *tmp_group= group; tmp_group; tmp_group=tmp_group->next)
  {
    Item *item= (*tmp_group->item)->real_item();
    if (item->type() == Item::FIELD_ITEM &&
        ((Item_field*) item)->field->eq(field))
    {
      part_found= 1;
      break;
    }
  }
  return part_found;
}


/*
  Helper function for list_contains_unique_index.
  Find a field reference in a dynamic list of Items.
  
  SYNOPSIS
    find_field_in_item_list ()
    field in             The field to search for.
    data  in             List<Item> *.The list to search in
  
  DESCRIPTION
    Finds a direct reference of the Field in the list.
  
  RETURN VALUE
    1                    found
    0                    not found.
*/

static bool
find_field_in_item_list (Field *field, void *data)
{
  List<Item> *fields= (List<Item> *) data;
  bool part_found= 0;
  List_iterator<Item> li(*fields);
  Item *item;

  while ((item= li++))
  {
    if (item->type() == Item::FIELD_ITEM &&
        ((Item_field*) item)->field->eq(field))
    {
      part_found= 1;
      break;
    }
  }
  return part_found;
}


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/*
  Test if we can skip the ORDER BY by using an index.

  If we can use an index, the JOIN_TAB / tab->select struct
  is changed to use the index.

  Return:
     0 We have to use filesort to do the sorting
     1 We can use an index.
*/
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static bool
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test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
			bool no_changes)
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{
  int ref_key;
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  uint ref_key_parts;
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  TABLE *table=tab->table;
  SQL_SELECT *select=tab->select;
  key_map usable_keys;
  DBUG_ENTER("test_if_skip_sort_order");
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  LINT_INIT(ref_key_parts);
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  /*
    Check which keys can be used to resolve ORDER BY.
    We must not try to use disabled keys.
  */
  usable_keys= table->keys_in_use;

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  for (ORDER *tmp_order=order; tmp_order ; tmp_order=tmp_order->next)
  {
    if ((*tmp_order->item)->type() != Item::FIELD_ITEM)
    {
7663
      usable_keys.clear_all();
7664
      DBUG_RETURN(0);
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    }
7666 7667
    usable_keys.intersect(((Item_field*) (*tmp_order->item))->
			  field->part_of_sortkey);
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    if (usable_keys.is_clear_all())
7669
      DBUG_RETURN(0);					// No usable keys
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  }

  ref_key= -1;
7673
  /* Test if constant range in WHERE */
7674
  if (tab->ref.key >= 0 && tab->ref.key_parts)
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  {
    ref_key=	   tab->ref.key;
    ref_key_parts= tab->ref.key_parts;
7678
    if (tab->type == JT_REF_OR_NULL || tab->type == JT_FT)
7679
      DBUG_RETURN(0);
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  }
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  else if (select && select->quick)		// Range found by opt_range
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  {
    ref_key=	   select->quick->index;
    ref_key_parts= select->quick->used_key_parts;
  }
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  if (ref_key >= 0)
  {
7689 7690 7691
    /*
      We come here when there is a REF key.
    */
7692
    int order_direction;
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    uint used_key_parts;
7694
    if (!usable_keys.is_set(ref_key))
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    {
      /*
	We come here when ref_key is not among usable_keys
      */
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      uint new_ref_key;
      /*
	If using index only read, only consider other possible index only
	keys
      */
7704
      if (table->used_keys.is_set(ref_key))
7705
	usable_keys.intersect(table->used_keys);
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      if ((new_ref_key= test_if_subkey(order, table, ref_key, ref_key_parts,
7707
				       &usable_keys)) < MAX_KEY)
7708
      {
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	/* Found key that can be used to retrieve data in sorted order */
7710 7711
	if (tab->ref.key >= 0)
	{
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          /*
            We'll use ref access method on key new_ref_key. In general case 
            the index search tuple for new_ref_key will be different (e.g.
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            when one index is defined as (part1, part2, ...) and another as
            (part1, part2(N), ...) and the WHERE clause contains 
            "part1 = const1 AND part2=const2". 
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            So we build tab->ref from scratch here.
          */
          KEYUSE *keyuse= tab->keyuse;
          while (keyuse->key != new_ref_key && keyuse->table == tab->table)
            keyuse++;
          if (create_ref_for_key(tab->join, tab, keyuse, 
                                 tab->join->const_table_map))
            DBUG_RETURN(0);
7726 7727 7728
	}
	else
	{
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          /*
            The range optimizer constructed QUICK_RANGE for ref_key, and
            we want to use instead new_ref_key as the index. We can't
            just change the index of the quick select, because this may
            result in an incosistent QUICK_SELECT object. Below we
            create a new QUICK_SELECT from scratch so that all its
            parameres are set correctly by the range optimizer.
           */
          key_map new_ref_key_map;
7738 7739
          new_ref_key_map.clear_all();  // Force the creation of quick select
          new_ref_key_map.set_bit(new_ref_key); // only for new_ref_key.
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          if (select->test_quick_select(tab->join->thd, new_ref_key_map, 0,
7742 7743 7744 7745 7746
                                        (tab->join->select_options &
                                         OPTION_FOUND_ROWS) ?
                                        HA_POS_ERROR :
                                        tab->join->unit->select_limit_cnt,0) <=
              0)
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            DBUG_RETURN(0);
7748
	}
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        ref_key= new_ref_key;
7750
      }
7751
    }
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    /* Check if we get the rows in requested sorted order by using the key */
7753
    if (usable_keys.is_set(ref_key) &&
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	(order_direction = test_if_order_by_key(order,table,ref_key,
						&used_key_parts)))
7756
    {
7757
      if (order_direction == -1)		// If ORDER BY ... DESC
7758
      {
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	if (select && select->quick)
	{
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	  /*
	    Don't reverse the sort order, if it's already done.
	    (In some cases test_if_order_by_key() can be called multiple times
	  */
	  if (!select->quick->reverse_sorted())
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	  {
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	    // ORDER BY range_key DESC
	    QUICK_SELECT_DESC *tmp=new QUICK_SELECT_DESC(select->quick,
							 used_key_parts);
	    if (!tmp || tmp->error)
	    {
	      delete tmp;
	      DBUG_RETURN(0);		// Reverse sort not supported
	    }
	    select->quick=tmp;
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	  }
	  DBUG_RETURN(1);
	}
	if (tab->ref.key_parts < used_key_parts)
	{
	  /*
	    SELECT * FROM t1 WHERE a=1 ORDER BY a DESC,b DESC
7783 7784 7785

	    Use a traversal function that starts by reading the last row
	    with key part (A) and then traverse the index backwards.
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	  */
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	  tab->read_first_record=       join_read_last_key;
	  tab->read_record.read_record= join_read_prev_same;
	  /* fall through */
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	}
7791
      }
7792 7793
      else if (select && select->quick)
	  select->quick->sorted= 1;
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      DBUG_RETURN(1);			/* No need to sort */
7795
    }
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  }
  else
  {
    /* check if we can use a key to resolve the group */
    /* Tables using JT_NEXT are handled here */
    uint nr;
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    key_map keys;
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    /*
      If not used with LIMIT, only use keys if the whole query can be
      resolved with a key;  This is because filesort() is usually faster than
      retrieving all rows through an index.
    */
    if (select_limit >= table->file->records)
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    {
      keys= *table->file->keys_to_use_for_scanning();
      keys.merge(table->used_keys);
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      /*
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	We are adding here also the index specified in FORCE INDEX clause, 
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	if any.
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        This is to allow users to use index in ORDER BY.
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      */
      if (table->force_index) 
	keys.merge(table->keys_in_use_for_query);
      keys.intersect(usable_keys);
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    }
    else
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      keys= usable_keys;
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    for (nr=0; nr < table->keys ; nr++)
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    {
7828
      uint not_used;
7829
      if (keys.is_set(nr))
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      {
	int flag;
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	if ((flag= test_if_order_by_key(order, table, nr, &not_used)))
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	{
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	  if (!no_changes)
	  {
	    tab->index=nr;
7837 7838
	    tab->read_first_record=  (flag > 0 ? join_read_first:
				      join_read_last);
7839
	    tab->type=JT_NEXT;	// Read with index_first(), index_next()
7840
	    if (table->used_keys.is_set(nr))
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	    {
	      table->key_read=1;
	      table->file->extra(HA_EXTRA_KEYREAD);
	    }
7845
	  }
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	  DBUG_RETURN(1);
	}
      }
    }
  }
  DBUG_RETURN(0);				// Can't use index.
}

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/*
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  If not selecting by given key, create an index how records should be read
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  SYNOPSIS
   create_sort_index()
     thd		Thread handler
     tab		Table to sort (in join structure)
     order		How table should be sorted
     filesort_limit	Max number of rows that needs to be sorted
     select_limit	Max number of rows in final output
7865
		        Used to decide if we should use index or not
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  IMPLEMENTATION
   - If there is an index that can be used, 'tab' is modified to use
     this index.
   - If no index, create with filesort() an index file that can be used to
     retrieve rows in order (should be done with 'read_record').
     The sorted data is stored in tab->table and will be freed when calling
     free_io_cache(tab->table).

  RETURN VALUES
    0		ok
    -1		Some fatal error
    1		No records
*/
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7881

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static int
7883
create_sort_index(THD *thd, JOIN *join, ORDER *order,
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		  ha_rows filesort_limit, ha_rows select_limit)
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{
  SORT_FIELD *sortorder;
  uint length;
7888
  ha_rows examined_rows;
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  TABLE *table;
  SQL_SELECT *select;
  JOIN_TAB *tab;
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  DBUG_ENTER("create_sort_index");

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  if (join->tables == join->const_tables)
    DBUG_RETURN(0);				// One row, no need to sort
  tab=    join->join_tab + join->const_tables;
  table=  tab->table;
  select= tab->select;

7900
  if (test_if_skip_sort_order(tab,order,select_limit,0))
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    DBUG_RETURN(0);
  if (!(sortorder=make_unireg_sortorder(order,&length)))
    goto err;				/* purecov: inspected */
  /* It's not fatal if the following alloc fails */
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  table->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
                                             MYF(MY_WME | MY_ZEROFILL));
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  table->status=0;				// May be wrong if quick_select

  // If table has a range, move it to select
  if (select && !select->quick && tab->ref.key >= 0)
  {
    if (tab->quick)
    {
      select->quick=tab->quick;
      tab->quick=0;
      /* We can only use 'Only index' if quick key is same as ref_key */
      if (table->key_read && (uint) tab->ref.key != select->quick->index)
      {
	table->key_read=0;
	table->file->extra(HA_EXTRA_NO_KEYREAD);
      }
    }
    else
    {
      /*
	We have a ref on a const;  Change this to a range that filesort
	can use.
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	For impossible ranges (like when doing a lookup on NULL on a NOT NULL
	field, quick will contain an empty record set.
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      */
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      if (!(select->quick= (tab->type == JT_FT ?
			    new FT_SELECT(thd, table, tab->ref.key) :
			    get_quick_select_for_ref(thd, table, &tab->ref))))
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	goto err;
    }
  }
7937 7938
  if (table->tmp_table)
    table->file->info(HA_STATUS_VARIABLE);	// Get record count
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  table->sort.found_records=filesort(thd, table,sortorder, length,
                                     select, filesort_limit, &examined_rows);
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  tab->records= table->sort.found_records;	// For SQL_CALC_ROWS
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  if (select)
  {
    select->cleanup();				// filesort did select
    tab->select= 0;
  }
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  tab->select_cond=0;
  tab->type=JT_ALL;				// Read with normal read_record
  tab->read_first_record= join_init_read_record;
7950
  tab->join->examined_rows+=examined_rows;
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  if (table->key_read)				// Restore if we used indexes
  {
    table->key_read=0;
    table->file->extra(HA_EXTRA_NO_KEYREAD);
  }
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  DBUG_RETURN(table->sort.found_records == HA_POS_ERROR);
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err:
  DBUG_RETURN(-1);
}

7961
/*
7962
  Add the HAVING criteria to table->select
7963 7964
*/

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#ifdef NOT_YET
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static bool fix_having(JOIN *join, Item **having)
{
  (*having)->update_used_tables();	// Some tables may have been const
  JOIN_TAB *table=&join->join_tab[join->const_tables];
  table_map used_tables= join->const_table_map | table->table->map;

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  DBUG_EXECUTE("where",print_where(*having,"having"););
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  Item* sort_table_cond=make_cond_for_table(*having,used_tables,used_tables);
  if (sort_table_cond)
  {
    if (!table->select)
      if (!(table->select=new SQL_SELECT))
	return 1;
    if (!table->select->cond)
      table->select->cond=sort_table_cond;
    else					// This should never happen
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      if (!(table->select->cond= new Item_cond_and(table->select->cond,
						   sort_table_cond)) ||
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	  table->select->cond->fix_fields(join->thd, join->tables_list,
7985
					  &table->select->cond))
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	return 1;
    table->select_cond=table->select->cond;
7988
    table->select_cond->top_level_item();
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    DBUG_EXECUTE("where",print_where(table->select_cond,
				     "select and having"););
    *having=make_cond_for_table(*having,~ (table_map) 0,~used_tables);
    DBUG_EXECUTE("where",print_where(*having,"having after make_cond"););
  }
  return 0;
}
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#endif
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/*****************************************************************************
8000 8001 8002 8003 8004
  Remove duplicates from tmp table
  This should be recoded to add a unique index to the table and remove
  duplicates
  Table is a locked single thread table
  fields is the number of fields to check (from the end)
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*****************************************************************************/

static bool compare_record(TABLE *table, Field **ptr)
{
  for (; *ptr ; ptr++)
  {
    if ((*ptr)->cmp_offset(table->rec_buff_length))
      return 1;
  }
  return 0;
}

static bool copy_blobs(Field **ptr)
{
  for (; *ptr ; ptr++)
  {
    if ((*ptr)->flags & BLOB_FLAG)
      if (((Field_blob *) (*ptr))->copy())
	return 1;				// Error
  }
  return 0;
}

static void free_blobs(Field **ptr)
{
  for (; *ptr ; ptr++)
  {
    if ((*ptr)->flags & BLOB_FLAG)
      ((Field_blob *) (*ptr))->free();
  }
}


static int
8039
remove_duplicates(JOIN *join, TABLE *entry,List<Item> &fields, Item *having)
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{
  int error;
  ulong reclength,offset;
  uint field_count;
8044
  THD *thd= join->thd;
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  DBUG_ENTER("remove_duplicates");

  entry->reginfo.lock_type=TL_WRITE;

  /* Calculate how many saved fields there is in list */
  field_count=0;
  List_iterator<Item> it(fields);
  Item *item;
  while ((item=it++))
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  {
8055
    if (item->get_tmp_table_field() && ! item->const_item())
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      field_count++;
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  }
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  if (!field_count && !(join->select_options & OPTION_FOUND_ROWS)) 
  {                    // only const items with no OPTION_FOUND_ROWS
8061
    join->unit->select_limit_cnt= 1;		// Only send first row
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    DBUG_RETURN(0);
  }
  Field **first_field=entry->field+entry->fields - field_count;
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  offset= field_count ? 
          entry->field[entry->fields - field_count]->offset() : 0;
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  reclength=entry->reclength-offset;

  free_io_cache(entry);				// Safety
  entry->file->info(HA_STATUS_VARIABLE);
  if (entry->db_type == DB_TYPE_HEAP ||
      (!entry->blob_fields &&
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       ((ALIGN_SIZE(reclength) + HASH_OVERHEAD) * entry->file->records <
8074
	thd->variables.sortbuff_size)))
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    error=remove_dup_with_hash_index(join->thd, entry,
				     field_count, first_field,
8077
				     reclength, having);
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  else
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    error=remove_dup_with_compare(join->thd, entry, first_field, offset,
				  having);
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  free_blobs(first_field);
  DBUG_RETURN(error);
}


static int remove_dup_with_compare(THD *thd, TABLE *table, Field **first_field,
8088
				   ulong offset, Item *having)
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{
  handler *file=table->file;
  char *org_record,*new_record;
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  byte *record;
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  int error;
  ulong reclength=table->reclength-offset;
  DBUG_ENTER("remove_dup_with_compare");

8097
  org_record=(char*) (record=table->record[0])+offset;
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  new_record=(char*) table->record[1]+offset;

8100
  file->ha_rnd_init(1);
8101
  error=file->rnd_next(record);
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  for (;;)
  {
    if (thd->killed)
    {
      my_error(ER_SERVER_SHUTDOWN,MYF(0));
      error=0;
      goto err;
    }
    if (error)
    {
      if (error == HA_ERR_RECORD_DELETED)
	continue;
      if (error == HA_ERR_END_OF_FILE)
	break;
      goto err;
    }
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    if (having && !having->val_int())
    {
      if ((error=file->delete_row(record)))
	goto err;
8122
      error=file->rnd_next(record);
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      continue;
    }
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    if (copy_blobs(first_field))
    {
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      my_error(ER_OUTOFMEMORY,MYF(0));
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      error=0;
      goto err;
    }
    memcpy(new_record,org_record,reclength);

    /* Read through rest of file and mark duplicated rows deleted */
    bool found=0;
    for (;;)
    {
8137
      if ((error=file->rnd_next(record)))
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      {
	if (error == HA_ERR_RECORD_DELETED)
	  continue;
	if (error == HA_ERR_END_OF_FILE)
	  break;
	goto err;
      }
      if (compare_record(table, first_field) == 0)
      {
8147
	if ((error=file->delete_row(record)))
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	  goto err;
      }
      else if (!found)
      {
	found=1;
8153
	file->position(record);	// Remember position
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      }
    }
    if (!found)
      break;					// End of file
    /* Restart search on next row */
8159
    error=file->restart_rnd_next(record,file->ref);
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  }

  file->extra(HA_EXTRA_NO_CACHE);
  DBUG_RETURN(0);
err:
  file->extra(HA_EXTRA_NO_CACHE);
  if (error)
    file->print_error(error,MYF(0));
  DBUG_RETURN(1);
}


/*
  Generate a hash index for each row to quickly find duplicate rows
  Note that this will not work on tables with blobs!
*/

static int remove_dup_with_hash_index(THD *thd, TABLE *table,
				      uint field_count,
				      Field **first_field,
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				      ulong key_length,
				      Item *having)
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{
  byte *key_buffer, *key_pos, *record=table->record[0];
  int error;
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  handler *file= table->file;
  ulong extra_length= ALIGN_SIZE(key_length)-key_length;
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  uint *field_lengths,*field_length;
  HASH hash;
  DBUG_ENTER("remove_dup_with_hash_index");

  if (!my_multi_malloc(MYF(MY_WME),
		       &key_buffer,
		       (uint) ((key_length + extra_length) *
			       (long) file->records),
		       &field_lengths,
		       (uint) (field_count*sizeof(*field_lengths)),
		       NullS))
    DBUG_RETURN(1);
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  {
    Field **ptr;
    ulong total_length= 0;
    for (ptr= first_field, field_length=field_lengths ; *ptr ; ptr++)
    {
      uint length= (*ptr)->pack_length();
      (*field_length++)= length;
      total_length+= length;
    }
    DBUG_PRINT("info",("field_count: %u  key_length: %lu  total_length: %lu",
                       field_count, key_length, total_length));
    DBUG_ASSERT(total_length <= key_length);
    key_length= total_length;
    extra_length= ALIGN_SIZE(key_length)-key_length;
  }

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  if (hash_init(&hash, &my_charset_bin, (uint) file->records, 0, 
8217
		key_length, (hash_get_key) 0, 0, 0))
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  {
    my_free((char*) key_buffer,MYF(0));
    DBUG_RETURN(1);
  }

8223
  file->ha_rnd_init(1);
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  key_pos=key_buffer;
  for (;;)
  {
8227
    byte *org_key_pos;
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    if (thd->killed)
    {
      my_error(ER_SERVER_SHUTDOWN,MYF(0));
      error=0;
      goto err;
    }
    if ((error=file->rnd_next(record)))
    {
      if (error == HA_ERR_RECORD_DELETED)
	continue;
      if (error == HA_ERR_END_OF_FILE)
	break;
      goto err;
    }
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    if (having && !having->val_int())
    {
      if ((error=file->delete_row(record)))
	goto err;
      continue;
8247
    }
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    /* copy fields to key buffer */
8250
    org_key_pos= key_pos;
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    field_length=field_lengths;
    for (Field **ptr= first_field ; *ptr ; ptr++)
    {
      (*ptr)->sort_string((char*) key_pos,*field_length);
      key_pos+= *field_length++;
    }
    /* Check if it exists before */
8258
    if (hash_search(&hash, org_key_pos, key_length))
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    {
      /* Duplicated found ; Remove the row */
      if ((error=file->delete_row(record)))
	goto err;
    }
8264
    else
8265
      (void) my_hash_insert(&hash, org_key_pos);
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    key_pos+=extra_length;
  }
  my_free((char*) key_buffer,MYF(0));
  hash_free(&hash);
  file->extra(HA_EXTRA_NO_CACHE);
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  (void) file->ha_rnd_end();
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  DBUG_RETURN(0);

err:
  my_free((char*) key_buffer,MYF(0));
  hash_free(&hash);
  file->extra(HA_EXTRA_NO_CACHE);
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  (void) file->ha_rnd_end();
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  if (error)
    file->print_error(error,MYF(0));
  DBUG_RETURN(1);
}


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SORT_FIELD *make_unireg_sortorder(ORDER *order, uint *length)
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{
  uint count;
  SORT_FIELD *sort,*pos;
  DBUG_ENTER("make_unireg_sortorder");

  count=0;
  for (ORDER *tmp = order; tmp; tmp=tmp->next)
    count++;
  pos=sort=(SORT_FIELD*) sql_alloc(sizeof(SORT_FIELD)*(count+1));
  if (!pos)
    return 0;

  for (;order;order=order->next,pos++)
  {
    pos->field=0; pos->item=0;
    if (order->item[0]->type() == Item::FIELD_ITEM)
      pos->field= ((Item_field*) (*order->item))->field;
    else if (order->item[0]->type() == Item::SUM_FUNC_ITEM &&
	     !order->item[0]->const_item())
8305
      pos->field= ((Item_sum*) order->item[0])->get_tmp_table_field();
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    else if (order->item[0]->type() == Item::COPY_STR_ITEM)
    {						// Blob patch
      pos->item= ((Item_copy_string*) (*order->item))->item;
    }
    else
      pos->item= *order->item;
    pos->reverse=! order->asc;
  }
  *length=count;
  DBUG_RETURN(sort);
}


/*****************************************************************************
8320 8321 8322 8323
  Fill join cache with packed records
  Records are stored in tab->cache.buffer and last record in
  last record is stored with pointers to blobs to support very big
  records
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******************************************************************************/

static int
join_init_cache(THD *thd,JOIN_TAB *tables,uint table_count)
{
  reg1 uint i;
  uint length,blobs,size;
  CACHE_FIELD *copy,**blob_ptr;
  JOIN_CACHE  *cache;
8333
  JOIN_TAB *join_tab;
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  DBUG_ENTER("join_init_cache");

  cache= &tables[table_count].cache;
  cache->fields=blobs=0;

8339 8340
  join_tab=tables;
  for (i=0 ; i < table_count ; i++,join_tab++)
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  {
8342 8343 8344 8345
    if (!join_tab->used_fieldlength)		/* Not calced yet */
      calc_used_field_length(thd, join_tab);
    cache->fields+=join_tab->used_fields;
    blobs+=join_tab->used_blobs;
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  }
  if (!(cache->field=(CACHE_FIELD*)
	sql_alloc(sizeof(CACHE_FIELD)*(cache->fields+table_count*2)+(blobs+1)*
		  sizeof(CACHE_FIELD*))))
  {
    my_free((gptr) cache->buff,MYF(0));		/* purecov: inspected */
    cache->buff=0;				/* purecov: inspected */
    DBUG_RETURN(1);				/* purecov: inspected */
  }
  copy=cache->field;
  blob_ptr=cache->blob_ptr=(CACHE_FIELD**)
    (cache->field+cache->fields+table_count*2);

  length=0;
  for (i=0 ; i < table_count ; i++)
  {
    uint null_fields=0,used_fields;

    Field **f_ptr,*field;
    for (f_ptr=tables[i].table->field,used_fields=tables[i].used_fields ;
	 used_fields ;
	 f_ptr++)
    {
      field= *f_ptr;
      if (field->query_id == thd->query_id)
      {
	used_fields--;
	length+=field->fill_cache_field(copy);
	if (copy->blob_field)
	  (*blob_ptr++)=copy;
	if (field->maybe_null())
	  null_fields++;
	copy++;
      }
    }
    /* Copy null bits from table */
    if (null_fields && tables[i].table->null_fields)
    {						/* must copy null bits */
      copy->str=(char*) tables[i].table->null_flags;
8385
      copy->length=tables[i].table->null_bytes;
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      copy->strip=0;
      copy->blob_field=0;
      length+=copy->length;
      copy++;
      cache->fields++;
    }
    /* If outer join table, copy null_row flag */
    if (tables[i].table->maybe_null)
    {
      copy->str= (char*) &tables[i].table->null_row;
      copy->length=sizeof(tables[i].table->null_row);
      copy->strip=0;
      copy->blob_field=0;
      length+=copy->length;
      copy++;
      cache->fields++;
    }
  }

  cache->length=length+blobs*sizeof(char*);
  cache->blobs=blobs;
  *blob_ptr=0;					/* End sequentel */
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  size=max(thd->variables.join_buff_size, cache->length);
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  if (!(cache->buff=(uchar*) my_malloc(size,MYF(0))))
    DBUG_RETURN(1);				/* Don't use cache */ /* purecov: inspected */
  cache->end=cache->buff+size;
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  reset_cache_write(cache);
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  DBUG_RETURN(0);
}


static ulong
used_blob_length(CACHE_FIELD **ptr)
{
  uint length,blob_length;
  for (length=0 ; *ptr ; ptr++)
  {
    (*ptr)->blob_length=blob_length=(*ptr)->blob_field->get_length();
    length+=blob_length;
    (*ptr)->blob_field->get_ptr(&(*ptr)->str);
  }
  return length;
}


static bool
store_record_in_cache(JOIN_CACHE *cache)
{
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  uint length;
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  uchar *pos;
  CACHE_FIELD *copy,*end_field;
  bool last_record;

  pos=cache->pos;
  end_field=cache->field+cache->fields;

  length=cache->length;
  if (cache->blobs)
    length+=used_blob_length(cache->blob_ptr);
  if ((last_record=(length+cache->length > (uint) (cache->end - pos))))
    cache->ptr_record=cache->records;

  /*
8449
    There is room in cache. Put record there
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  */
  cache->records++;
  for (copy=cache->field ; copy < end_field; copy++)
  {
    if (copy->blob_field)
    {
      if (last_record)
      {
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	copy->blob_field->get_image((char*) pos,copy->length+sizeof(char*), 
				    copy->blob_field->charset());
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	pos+=copy->length+sizeof(char*);
      }
      else
      {
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	copy->blob_field->get_image((char*) pos,copy->length, // blob length
				    copy->blob_field->charset());
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	memcpy(pos+copy->length,copy->str,copy->blob_length);  // Blob data
	pos+=copy->length+copy->blob_length;
      }
    }
    else
    {
      if (copy->strip)
      {
	char *str,*end;
	for (str=copy->str,end= str+copy->length;
	     end > str && end[-1] == ' ' ;
	     end--) ;
	length=(uint) (end-str);
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	memcpy(pos+2, str, length);
        int2store(pos, length);
	pos+= length+2;
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      }
      else
      {
	memcpy(pos,copy->str,copy->length);
	pos+=copy->length;
      }
    }
  }
  cache->pos=pos;
  return last_record || (uint) (cache->end -pos) < cache->length;
}


static void
8496
reset_cache_read(JOIN_CACHE *cache)
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{
  cache->record_nr=0;
  cache->pos=cache->buff;
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}


static void reset_cache_write(JOIN_CACHE *cache)
{
  reset_cache_read(cache);
  cache->records= 0;
  cache->ptr_record= (uint) ~0;
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}


static void
read_cached_record(JOIN_TAB *tab)
{
  uchar *pos;
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  uint length;
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  bool last_record;
  CACHE_FIELD *copy,*end_field;

  last_record=tab->cache.record_nr++ == tab->cache.ptr_record;
  pos=tab->cache.pos;

  for (copy=tab->cache.field,end_field=copy+tab->cache.fields ;
       copy < end_field;
       copy++)
  {
    if (copy->blob_field)
    {
      if (last_record)
      {
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	copy->blob_field->set_image((char*) pos,copy->length+sizeof(char*),
				    copy->blob_field->charset());
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	pos+=copy->length+sizeof(char*);
      }
      else
      {
	copy->blob_field->set_ptr((char*) pos,(char*) pos+copy->length);
	pos+=copy->length+copy->blob_field->get_length();
      }
    }
    else
    {
      if (copy->strip)
      {
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        length= uint2korr(pos);
	memcpy(copy->str, pos+2, length);
8546
	memset(copy->str+length, ' ', copy->length-length);
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	pos+= 2 + length;
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      }
      else
      {
	memcpy(copy->str,pos,copy->length);
	pos+=copy->length;
      }
    }
  }
  tab->cache.pos=pos;
  return;
}


static bool
cmp_buffer_with_ref(JOIN_TAB *tab)
{
  bool diff;
  if (!(diff=tab->ref.key_err))
  {
    memcpy(tab->ref.key_buff2, tab->ref.key_buff, tab->ref.key_length);
  }
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  if ((tab->ref.key_err= cp_buffer_from_ref(tab->join->thd, &tab->ref)) || 
      diff)
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    return 1;
  return memcmp(tab->ref.key_buff2, tab->ref.key_buff, tab->ref.key_length)
    != 0;
}


bool
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cp_buffer_from_ref(THD *thd, TABLE_REF *ref)
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{
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  enum enum_check_fields save_count_cuted_fields= thd->count_cuted_fields;
  thd->count_cuted_fields= CHECK_FIELD_IGNORE;
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  for (store_key **copy=ref->key_copy ; *copy ; copy++)
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  {
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    if ((*copy)->copy() & 1)
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    {
      thd->count_cuted_fields= save_count_cuted_fields;
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      return 1;                                 // Something went wrong
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    }
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  }
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  thd->count_cuted_fields= save_count_cuted_fields;
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  return 0;
}


/*****************************************************************************
8596
  Group and order functions
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*****************************************************************************/

/*
8600 8601 8602
  Find order/group item in requested columns and change the item to point at
  it. If item doesn't exists, add it first in the field list
  Return 0 if ok.
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*/

static int
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find_order_in_list(THD *thd, Item **ref_pointer_array,
		   TABLE_LIST *tables,ORDER *order, List<Item> &fields,
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		   List<Item> &all_fields)
{
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  Item *it= *order->item;
  if (it->type() == Item::INT_ITEM)
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  {						/* Order by position */
8613
    uint count= (uint) it->val_int();
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    if (!count || count > fields.elements)
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    {
      my_printf_error(ER_BAD_FIELD_ERROR,ER(ER_BAD_FIELD_ERROR),
8617
		      MYF(0), it->full_name(), thd->where);
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      return 1;
    }
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    order->item= ref_pointer_array + count-1;
    order->in_field_list= 1;
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    return 0;
  }
8624
  uint counter;
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  bool unaliased;
  Item **item= find_item_in_list(it, fields, &counter,
                                 REPORT_EXCEPT_NOT_FOUND, &unaliased);
8628 8629 8630
  if (!item)
    return 1;

8631
  if (item != (Item **)not_found_item)
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  {
8633 8634 8635 8636 8637 8638 8639 8640
    /*
      If we have found field not by its alias in select list but by its
      original field name, we should additionaly check if we have conflict
      for this name (in case if we would perform lookup in all tables).
    */
    if (unaliased && !it->fixed && it->fix_fields(thd, tables, order->item))
      return 1;

8641
    order->item= ref_pointer_array + counter;
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    order->in_field_list=1;
    return 0;
  }
8645

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  order->in_field_list=0;
8647
  /*
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    We check it->fixed because Item_func_group_concat can put
    arguments for which fix_fields already was called.

    'it' reassigned in if condition because fix_field can change it.
8652
  */
8653
  thd->lex->current_select->is_item_list_lookup= 1;
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  if (!it->fixed &&
      (it->fix_fields(thd, tables, order->item) ||
       (it= *order->item)->check_cols(1) ||
       thd->is_fatal_error))
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  {
    thd->lex->current_select->is_item_list_lookup= 0;
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    return 1;					// Wrong field 
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  }
  thd->lex->current_select->is_item_list_lookup= 0;
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  uint el= all_fields.elements;
  all_fields.push_front(it);		        // Add new field to field list
  ref_pointer_array[el]= it;
  order->item= ref_pointer_array + el;
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  return 0;
}

/*
8671 8672
  Change order to point at item in select list. If item isn't a number
  and doesn't exits in the select list, add it the the field list.
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*/

8675 8676
int setup_order(THD *thd, Item **ref_pointer_array, TABLE_LIST *tables,
		List<Item> &fields, List<Item> &all_fields, ORDER *order)
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{
  thd->where="order clause";
  for (; order; order=order->next)
  {
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    if (find_order_in_list(thd, ref_pointer_array, tables, order, fields,
			   all_fields))
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      return 1;
  }
  return 0;
}


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/*
  Intitialize the GROUP BY list.

  SYNOPSIS
   setup_group()
   thd			Thread handler
   ref_pointer_array	We store references to all fields that was not in
			'fields' here.   
   fields		All fields in the select part. Any item in 'order'
			that is part of these list is replaced by a pointer
			to this fields.
   all_fields		Total list of all unique fields used by the select.
			All items in 'order' that was not part of fields will
			be added first to this list.
  order			The fields we should do GROUP BY on.
  hidden_group_fields	Pointer to flag that is set to 1 if we added any fields
			to all_fields.

  RETURN
   0  ok
   1  error (probably out of memory)
*/

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int
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setup_group(THD *thd, Item **ref_pointer_array, TABLE_LIST *tables,
	    List<Item> &fields, List<Item> &all_fields, ORDER *order,
	    bool *hidden_group_fields)
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{
  *hidden_group_fields=0;
  if (!order)
    return 0;				/* Everything is ok */

8721
  if (thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY)
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  {
    Item *item;
    List_iterator<Item> li(fields);
    while ((item=li++))
      item->marker=0;			/* Marker that field is not used */
  }
  uint org_fields=all_fields.elements;

  thd->where="group statement";
8731
  for (; order; order=order->next)
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  {
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    if (find_order_in_list(thd, ref_pointer_array, tables, order, fields,
			   all_fields))
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      return 1;
    (*order->item)->marker=1;		/* Mark found */
    if ((*order->item)->with_sum_func)
    {
      my_printf_error(ER_WRONG_GROUP_FIELD, ER(ER_WRONG_GROUP_FIELD),MYF(0),
		      (*order->item)->full_name());
      return 1;
    }
  }
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  if (thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY)
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  {
    /* Don't allow one to use fields that is not used in GROUP BY */
    Item *item;
    List_iterator<Item> li(fields);

    while ((item=li++))
    {
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      if (item->type() != Item::SUM_FUNC_ITEM && !item->marker &&
	  !item->const_item())
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      {
	my_printf_error(ER_WRONG_FIELD_WITH_GROUP,
			ER(ER_WRONG_FIELD_WITH_GROUP),
			MYF(0),item->full_name());
	return 1;
      }
    }
  }
  if (org_fields != all_fields.elements)
    *hidden_group_fields=1;			// group fields is not used
  return 0;
}

/*
8768
  Add fields with aren't used at start of field list. Return FALSE if ok
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*/

static bool
setup_new_fields(THD *thd,TABLE_LIST *tables,List<Item> &fields,
		 List<Item> &all_fields, ORDER *new_field)
{
  Item	  **item;
  DBUG_ENTER("setup_new_fields");

  thd->set_query_id=1;				// Not really needed, but...
8779
  uint counter;
8780
  bool not_used;
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  for (; new_field ; new_field= new_field->next)
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  {
8783
    if ((item= find_item_in_list(*new_field->item, fields, &counter,
8784
				 IGNORE_ERRORS, &not_used)))
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      new_field->item=item;			/* Change to shared Item */
    else
    {
      thd->where="procedure list";
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      if ((*new_field->item)->fix_fields(thd, tables, new_field->item))
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	DBUG_RETURN(1); /* purecov: inspected */
      all_fields.push_front(*new_field->item);
      new_field->item=all_fields.head_ref();
    }
  }
  DBUG_RETURN(0);
}

/*
8799 8800 8801
  Create a group by that consist of all non const fields. Try to use
  the fields in the order given by 'order' to allow one to optimize
  away 'order by'.
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*/

static ORDER *
8805 8806
create_distinct_group(THD *thd, Item **ref_pointer_array,
                      ORDER *order_list, List<Item> &fields, 
8807
		      bool *all_order_by_fields_used)
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{
  List_iterator<Item> li(fields);
  Item *item;
  ORDER *order,*group,**prev;
8812
  uint index= 0;
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8814
  *all_order_by_fields_used= 1;
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  while ((item=li++))
    item->marker=0;			/* Marker that field is not used */

  prev= &group;  group=0;
  for (order=order_list ; order; order=order->next)
  {
    if (order->in_field_list)
    {
8823
      ORDER *ord=(ORDER*) thd->memdup((char*) order,sizeof(ORDER));
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      if (!ord)
	return 0;
      *prev=ord;
      prev= &ord->next;
      (*ord->item)->marker=1;
    }
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    else
      *all_order_by_fields_used= 0;
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  }

  li.rewind();
  while ((item=li++))
  {
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    if (!item->const_item() && !item->with_sum_func && !item->marker)
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    {
8839
      ORDER *ord=(ORDER*) thd->calloc(sizeof(ORDER));
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      if (!ord)
	return 0;
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      /*
        We have here only field_list (not all_field_list), so we can use
        simple indexing of ref_pointer_array (order in the array and in the
        list are same)
      */
      ord->item= ref_pointer_array + index;
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      ord->asc=1;
      *prev=ord;
      prev= &ord->next;
    }
8852
    index++;
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  }
  *prev=0;
  return group;
}


/*****************************************************************************
8860
  Update join with count of the different type of fields
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*****************************************************************************/

void
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count_field_types(TMP_TABLE_PARAM *param, List<Item> &fields,
		  bool reset_with_sum_func)
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{
  List_iterator<Item> li(fields);
  Item *field;

8870
  param->field_count=param->sum_func_count=param->func_count=
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    param->hidden_field_count=0;
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  param->quick_group=1;
  while ((field=li++))
  {
    Item::Type type=field->type();
    if (type == Item::FIELD_ITEM)
      param->field_count++;
    else if (type == Item::SUM_FUNC_ITEM)
    {
      if (! field->const_item())
      {
	Item_sum *sum_item=(Item_sum*) field;
	if (!sum_item->quick_group)
	  param->quick_group=0;			// UDF SUM function
	param->sum_func_count++;

	for (uint i=0 ; i < sum_item->arg_count ; i++)
	{
	  if (sum_item->args[0]->type() == Item::FIELD_ITEM)
	    param->field_count++;
	  else
	    param->func_count++;
	}
      }
    }
    else
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    {
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      param->func_count++;
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      if (reset_with_sum_func)
	field->with_sum_func=0;
    }
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  }
}


/*
  Return 1 if second is a subpart of first argument
  If first parts has different direction, change it to second part
  (group is sorted like order)
*/

static bool
test_if_subpart(ORDER *a,ORDER *b)
{
  for (; a && b; a=a->next,b=b->next)
  {
8917
    if ((*a->item)->eq(*b->item,1))
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      a->asc=b->asc;
    else
      return 0;
  }
  return test(!b);
}

/*
  Return table number if there is only one table in sort order
  and group and order is compatible
  else return 0;
*/

static TABLE *
get_sort_by_table(ORDER *a,ORDER *b,TABLE_LIST *tables)
{
  table_map map= (table_map) 0;
  DBUG_ENTER("get_sort_by_table");

  if (!a)
    a=b;					// Only one need to be given
  else if (!b)
    b=a;

  for (; a && b; a=a->next,b=b->next)
  {
8944
    if (!(*a->item)->eq(*b->item,1))
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      DBUG_RETURN(0);
    map|=a->item[0]->used_tables();
  }
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  if (!map || (map & (RAND_TABLE_BIT | OUTER_REF_TABLE_BIT)))
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    DBUG_RETURN(0);

8951
  for (; !(map & tables->table->map) ; tables=tables->next) ;
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  if (map != tables->table->map)
    DBUG_RETURN(0);				// More than one table
  DBUG_PRINT("exit",("sort by table: %d",tables->table->tablenr));
  DBUG_RETURN(tables->table);
}


	/* calc how big buffer we need for comparing group entries */

static void
calc_group_buffer(JOIN *join,ORDER *group)
{
8964 8965
  uint key_length=0, parts=0, null_parts=0;

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  if (group)
    join->group= 1;
  for (; group ; group=group->next)
  {
8970
    Field *field=(*group->item)->get_tmp_table_field();
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    if (field)
    {
      if (field->type() == FIELD_TYPE_BLOB)
	key_length+=MAX_BLOB_WIDTH;		// Can't be used as a key
      else
	key_length+=field->pack_length();
    }
    else if ((*group->item)->result_type() == REAL_RESULT)
      key_length+=sizeof(double);
    else if ((*group->item)->result_type() == INT_RESULT)
      key_length+=sizeof(longlong);
    else
      key_length+=(*group->item)->max_length;
    parts++;
    if ((*group->item)->maybe_null)
8986
      null_parts++;
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  }
8988
  join->tmp_table_param.group_length=key_length+null_parts;
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  join->tmp_table_param.group_parts=parts;
8990
  join->tmp_table_param.group_null_parts=null_parts;
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}

8993

8994
/*
8995
  allocate group fields or take prepared (cached)
8996

8997
  SYNOPSIS
8998 8999 9000 9001 9002 9003 9004 9005 9006 9007 9008 9009
    make_group_fields()
    main_join - join of current select
    curr_join - current join (join of current select or temporary copy of it)

  RETURN
    0 - ok
    1 - failed
*/

static bool
make_group_fields(JOIN *main_join, JOIN *curr_join)
{
9010 9011 9012 9013 9014 9015 9016 9017 9018 9019 9020 9021
  if (main_join->group_fields_cache.elements)
  {
    curr_join->group_fields= main_join->group_fields_cache;
    curr_join->sort_and_group= 1;
  }
  else
  {
    if (alloc_group_fields(curr_join, curr_join->group_list))
      return (1);
    main_join->group_fields_cache= curr_join->group_fields;
  }
  return (0);
9022
}
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9024

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/*
9026 9027
  Get a list of buffers for saveing last group
  Groups are saved in reverse order for easyer check loop
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*/

static bool
alloc_group_fields(JOIN *join,ORDER *group)
{
  if (group)
  {
    for (; group ; group=group->next)
    {
9037
      Item_buff *tmp=new_Item_buff(join->thd, *group->item);
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      if (!tmp || join->group_fields.push_front(tmp))
	return TRUE;
    }
  }
  join->sort_and_group=1;			/* Mark for do_select */
  return FALSE;
}


static int
test_if_group_changed(List<Item_buff> &list)
{
9050
  DBUG_ENTER("test_if_group_changed");
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  List_iterator<Item_buff> li(list);
  int idx= -1,i;
  Item_buff *buff;

  for (i=(int) list.elements-1 ; (buff=li++) ; i--)
  {
    if (buff->cmp())
      idx=i;
  }
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  DBUG_PRINT("info", ("idx: %d", idx));
  DBUG_RETURN(idx);
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}


/*
9066
  Setup copy_fields to save fields at start of new group
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  setup_copy_fields()
    thd - THD pointer
    param - temporary table parameters
    ref_pointer_array - array of pointers to top elements of filed list
    res_selected_fields - new list of items of select item list
    res_all_fields - new list of all items
    elements - number of elements in select item list
    all_fields - all fields list

  DESCRIPTION
    Setup copy_fields to save fields at start of new group
    Only FIELD_ITEM:s and FUNC_ITEM:s needs to be saved between groups.
    Change old item_field to use a new field with points at saved fieldvalue
    This function is only called before use of send_fields
  
  RETURN
    0 - ok
    !=0 - error
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*/

bool
9089 9090
setup_copy_fields(THD *thd, TMP_TABLE_PARAM *param,
		  Item **ref_pointer_array,
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		  List<Item> &res_selected_fields, List<Item> &res_all_fields,
		  uint elements, List<Item> &all_fields)
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{
  Item *pos;
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  List_iterator_fast<Item> li(all_fields);
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  Copy_field *copy= NULL;
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  res_selected_fields.empty();
  res_all_fields.empty();
  List_iterator_fast<Item> itr(res_all_fields);
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  List<Item> extra_funcs;
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  uint i, border= all_fields.elements - elements;
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  DBUG_ENTER("setup_copy_fields");
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9103

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  if (param->field_count && 
      !(copy=param->copy_field= new Copy_field[param->field_count]))
9106
    goto err2;
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  param->copy_funcs.empty();
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  for (i= 0; (pos= li++); i++)
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  {
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    Field *field;
    char *tmp;
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    if (pos->type() == Item::FIELD_ITEM)
    {
9115
      Item_field *item;
9116
      if (!(item= new Item_field(thd, ((Item_field*) pos))))
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	goto err;
      pos= item;
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      if (item->field->flags & BLOB_FLAG)
      {
9121
	if (!(pos= new Item_copy_string(pos)))
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	  goto err;
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       /*
         Item_copy_string::copy for function can call 
         Item_copy_string::val_int for blob via Item_ref.
         But if Item_copy_string::copy for blob isn't called before,
         it's value will be wrong
         so let's insert Item_copy_string for blobs in the beginning of 
         copy_funcs
         (to see full test case look at having.test, BUG #4358) 
       */
	if (param->copy_funcs.push_front(pos))
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	  goto err;
      }
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      else
      {
	/* 
	   set up save buffer and change result_field to point at 
	   saved value
	*/
9141
	field= item->field;
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	item->result_field=field->new_field(thd->mem_root,field->table);
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        /*
          We need to allocate one extra byte for null handling and
          another extra byte to not get warnings from purify in
          Field_string::val_int
        */
	tmp= (char*) sql_alloc(field->pack_length()+2);
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	if (!tmp)
	  goto err;
	copy->set(tmp, item->result_field);
	item->result_field->move_field(copy->to_ptr,copy->to_null_ptr,1);
9153
#ifdef HAVE_purify
9154
        copy->to_ptr[copy->from_length]= 0;
9155
#endif
9156
        copy++;
9157
      }
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    }
    else if ((pos->type() == Item::FUNC_ITEM ||
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	      pos->type() == Item::SUBSELECT_ITEM ||
	      pos->type() == Item::CACHE_ITEM ||
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	      pos->type() == Item::COND_ITEM) &&
	     !pos->with_sum_func)
    {						// Save for send fields
      /* TODO:
	 In most cases this result will be sent to the user.
	 This should be changed to use copy_int or copy_real depending
	 on how the value is to be used: In some cases this may be an
	 argument in a group function, like: IF(ISNULL(col),0,COUNT(*))
      */
      if (!(pos=new Item_copy_string(pos)))
	goto err;
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      if (i < border)                           // HAVING, ORDER and GROUP BY
      {
        if (extra_funcs.push_back(pos))
          goto err;
      }
      else if (param->copy_funcs.push_back(pos))
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	goto err;
    }
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    res_all_fields.push_back(pos);
    ref_pointer_array[((i < border)? all_fields.elements-i-1 : i-border)]=
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      pos;
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  }
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  param->copy_field_end= copy;
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  for (i= 0; i < border; i++)
    itr++;
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  itr.sublist(res_selected_fields, elements);
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  /*
    Put elements from HAVING, ORDER BY and GROUP BY last to ensure that any
    reference used in these will resolve to a item that is already calculated
  */
  param->copy_funcs.concat(&extra_funcs);

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  DBUG_RETURN(0);

 err:
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  if (copy)
    delete [] param->copy_field;
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  param->copy_field=0;
9202
err2:
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  DBUG_RETURN(TRUE);
}


/*
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  Make a copy of all simple SELECT'ed items

  This is done at the start of a new group so that we can retrieve
  these later when the group changes.
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*/

void
copy_fields(TMP_TABLE_PARAM *param)
{
  Copy_field *ptr=param->copy_field;
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  Copy_field *end=param->copy_field_end;
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  for (; ptr != end; ptr++)
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    (*ptr->do_copy)(ptr);

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  List_iterator_fast<Item> it(param->copy_funcs);
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  Item_copy_string *item;
  while ((item = (Item_copy_string*) it++))
    item->copy();
}


9230 9231
/*
  Make an array of pointers to sum_functions to speed up sum_func calculation
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  SYNOPSIS
    alloc_func_list()

  RETURN
    0	ok
    1	Error
*/

bool JOIN::alloc_func_list()
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{
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  uint func_count, group_parts;
  DBUG_ENTER("alloc_func_list");

  func_count= tmp_table_param.sum_func_count;
  /*
    If we are using rollup, we need a copy of the summary functions for
    each level
  */
  if (rollup.state != ROLLUP::STATE_NONE)
    func_count*= (send_group_parts+1);

  group_parts= send_group_parts;
  /*
    If distinct, reserve memory for possible
    disctinct->group_by optimization
  */
  if (select_distinct)
    group_parts+= fields_list.elements;

  /* This must use calloc() as rollup_make_fields depends on this */
  sum_funcs= (Item_sum**) thd->calloc(sizeof(Item_sum**) * (func_count+1) +
				      sizeof(Item_sum***) * (group_parts+1));
  sum_funcs_end= (Item_sum***) (sum_funcs+func_count+1);
  DBUG_RETURN(sum_funcs == 0);
}


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/*
  Initialize 'sum_funcs' array with all Item_sum objects

  SYNOPSIS
    make_sum_func_list()
    field_list		All items
    send_fields		Items in select list
    before_group_by	Set to 1 if this is called before GROUP BY handling

  NOTES
    Calls ::setup() for all item_sum objects in field_list

  RETURN
    0  ok
    1  error
*/

9287
bool JOIN::make_sum_func_list(List<Item> &field_list, List<Item> &send_fields,
9288
			      bool before_group_by)
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{
9290
  List_iterator_fast<Item> it(field_list);
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  Item_sum **func;
  Item *item;
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  DBUG_ENTER("make_sum_func_list");

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  func= sum_funcs;
  while ((item=it++))
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  {
9298
    if (item->type() == Item::SUM_FUNC_ITEM && !item->const_item())
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    {
9300
      *func++= (Item_sum*) item;
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      /* let COUNT(DISTINCT) create the temporary table */
9302
      if (((Item_sum*) item)->setup(thd))
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	DBUG_RETURN(TRUE);
    }
  }
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  if (before_group_by && rollup.state == ROLLUP::STATE_INITED)
  {
    rollup.state= ROLLUP::STATE_READY;
9309
    if (rollup_make_fields(field_list, send_fields, &func))
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      DBUG_RETURN(TRUE);			// Should never happen
  }
  else if (rollup.state == ROLLUP::STATE_NONE)
  {
    for (uint i=0 ; i <= send_group_parts ;i++)
      sum_funcs_end[i]= func;
  }
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  else if (rollup.state == ROLLUP::STATE_READY)
    DBUG_RETURN(FALSE);                         // Don't put end marker
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  *func=0;					// End marker
  DBUG_RETURN(FALSE);
}


/*
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  Change all funcs and sum_funcs to fields in tmp table, and create
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  new list of all items.

  change_to_use_tmp_fields()
    thd - THD pointer
    ref_pointer_array - array of pointers to top elements of filed list
    res_selected_fields - new list of items of select item list
    res_all_fields - new list of all items
    elements - number of elements in select item list
    all_fields - all fields list

   RETURN
    0 - ok
    !=0 - error
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*/

static bool
9342
change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
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			 List<Item> &res_selected_fields,
			 List<Item> &res_all_fields,
			 uint elements, List<Item> &all_fields)
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{
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  List_iterator_fast<Item> it(all_fields);
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  Item *item_field,*item;
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  res_selected_fields.empty();
  res_all_fields.empty();
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  uint i, border= all_fields.elements - elements;
9353
  for (i= 0; (item= it++); i++)
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  {
    Field *field;
9356
    
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    if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM)
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      item_field= item;
    else
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    {
9361
      if (item->type() == Item::FIELD_ITEM)
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      {
9363
	item_field= item->get_tmp_table_item(thd);
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      }
9365
      else if ((field= item->get_tmp_table_field()))
9366 9367 9368 9369
      {
	if (item->type() == Item::SUM_FUNC_ITEM && field->table->group)
	  item_field= ((Item_sum*) item)->result_item(field);
	else
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	  item_field= (Item*) new Item_field(field);
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	if (!item_field)
	  return TRUE;				// Fatal error
	item_field->name= item->name;		/*lint -e613 */
#ifndef DBUG_OFF
	if (_db_on_ && !item_field->name)
	{
	  char buff[256];
9378
	  String str(buff,sizeof(buff),&my_charset_bin);
9379 9380 9381 9382
	  str.length(0);
	  item->print(&str);
	  item_field->name= sql_strmake(str.ptr(),str.length());
	}
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#endif
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      }
      else
	item_field= item;
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    }
    res_all_fields.push_back(item_field);
    ref_pointer_array[((i < border)? all_fields.elements-i-1 : i-border)]=
9390
      item_field;
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  }
9392

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  List_iterator_fast<Item> itr(res_all_fields);
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  for (i= 0; i < border; i++)
    itr++;
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  itr.sublist(res_selected_fields, elements);
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  return FALSE;
}


/*
9402 9403
  Change all sum_func refs to fields to point at fields in tmp table
  Change all funcs to be fields in tmp table
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  change_refs_to_tmp_fields()
    thd - THD pointer
    ref_pointer_array - array of pointers to top elements of filed list
    res_selected_fields - new list of items of select item list
    res_all_fields - new list of all items
    elements - number of elements in select item list
    all_fields - all fields list

   RETURN
9414 9415
    0	ok
    1	error
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*/

static bool
9419
change_refs_to_tmp_fields(THD *thd, Item **ref_pointer_array,
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			  List<Item> &res_selected_fields,
			  List<Item> &res_all_fields, uint elements,
			  List<Item> &all_fields)
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{
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  List_iterator_fast<Item> it(all_fields);
9425
  Item *item, *new_item;
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  res_selected_fields.empty();
  res_all_fields.empty();
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  uint i, border= all_fields.elements - elements;
9430
  for (i= 0; (item= it++); i++)
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  {
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    res_all_fields.push_back(new_item= item->get_tmp_table_item(thd));
    ref_pointer_array[((i < border)? all_fields.elements-i-1 : i-border)]=
9434
      new_item;
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  }
9436

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  List_iterator_fast<Item> itr(res_all_fields);
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  for (i= 0; i < border; i++)
    itr++;
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  itr.sublist(res_selected_fields, elements);
9441

9442
  return thd->is_fatal_error;
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}



/******************************************************************************
9448
  Code for calculating functions
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******************************************************************************/

static void
init_tmptable_sum_functions(Item_sum **func_ptr)
{
  Item_sum *func;
  while ((func= *(func_ptr++)))
    func->reset_field();
}


	/* Update record 0 in tmp_table from record 1 */

static void
update_tmptable_sum_func(Item_sum **func_ptr,
			 TABLE *tmp_table __attribute__((unused)))
{
  Item_sum *func;
  while ((func= *(func_ptr++)))
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    func->update_field();
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}


	/* Copy result of sum functions to record in tmp_table */

static void
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copy_sum_funcs(Item_sum **func_ptr, Item_sum **end_ptr)
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{
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  for (; func_ptr != end_ptr ; func_ptr++)
    (void) (*func_ptr)->save_in_result_field(1);
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  return;
}


9483 9484
static bool
init_sum_functions(Item_sum **func_ptr, Item_sum **end_ptr)
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{
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  for (; func_ptr != end_ptr ;func_ptr++)
  {
    if ((*func_ptr)->reset())
      return 1;
  }
  /* If rollup, calculate the upper sum levels */
  for ( ; *func_ptr ; func_ptr++)
  {
    if ((*func_ptr)->add())
      return 1;
  }
  return 0;
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}


static bool
update_sum_func(Item_sum **func_ptr)
{
  Item_sum *func;
  for (; (func= (Item_sum*) *func_ptr) ; func_ptr++)
    if (func->add())
      return 1;
  return 0;
}

	/* Copy result of functions to record in tmp_table */

void
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copy_funcs(Item **func_ptr)
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{
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  Item *func;
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  for (; (func = *func_ptr) ; func_ptr++)
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    func->save_in_result_field(1);
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}


9522
/*
9523 9524
  Create a condition for a const reference and add this to the
  currenct select for the table
9525
*/
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static bool add_ref_to_table_cond(THD *thd, JOIN_TAB *join_tab)
{
  DBUG_ENTER("add_ref_to_table_cond");
  if (!join_tab->ref.key_parts)
    DBUG_RETURN(FALSE);

  Item_cond_and *cond=new Item_cond_and();
  TABLE *table=join_tab->table;
  int error;
  if (!cond)
    DBUG_RETURN(TRUE);

  for (uint i=0 ; i < join_tab->ref.key_parts ; i++)
  {
9541 9542
    Field *field=table->field[table->key_info[join_tab->ref.key].key_part[i].
			      fieldnr-1];
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    Item *value=join_tab->ref.items[i];
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    cond->add(new Item_func_equal(new Item_field(field), value));
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  }
9546
  if (thd->is_fatal_error)
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    DBUG_RETURN(TRUE);
9548

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  if (!cond->fixed)
    cond->fix_fields(thd,(TABLE_LIST *) 0, (Item**)&cond);
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  if (join_tab->select)
  {
    error=(int) cond->add(join_tab->select->cond);
    join_tab->select_cond=join_tab->select->cond=cond;
  }
  else if ((join_tab->select=make_select(join_tab->table, 0, 0, cond,&error)))
    join_tab->select_cond=cond;

  DBUG_RETURN(error ? TRUE : FALSE);
}

9562 9563 9564 9565 9566 9567 9568 9569 9570 9571 9572 9573 9574 9575 9576 9577 9578

/*
  Free joins of subselect of this select.

  free_underlaid_joins()
    thd - THD pointer
    select - pointer to st_select_lex which subselects joins we will free
*/

void free_underlaid_joins(THD *thd, SELECT_LEX *select)
{
  for (SELECT_LEX_UNIT *unit= select->first_inner_unit();
       unit;
       unit= unit->next_unit())
    unit->cleanup();
}

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/****************************************************************************
9580 9581 9582
  ROLLUP handling
****************************************************************************/

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/*
  Replace occurences of group by fields in an expression by ref items

  SYNOPSIS
    change_group_ref()
    thd                  reference to the context
    expr                 expression to make replacement
    group_list           list of references to group by items
    changed        out:  returns 1 if item contains a replaced field item 
     
  DESCRIPTION
    The function replaces occurrences of group by fields in expr
    by ref objects for these fields unless they are under aggregate
    functions.
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    The function also corrects value of the the maybe_null attribute
    for the items of all subexpressions containing group by fields.
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  IMPLEMENTATION
    The function recursively traverses the tree of the expr expression,
    looks for occurrences of the group by fields that are not under
    aggregate functions and replaces them for the corresponding ref items.

  NOTES
    This substitution is needed GROUP BY queries with ROLLUP if
    SELECT list contains expressions over group by attributes.

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  TODO: Some functions are not null-preserving. For those functions
    updating of the maybe_null attribute is an overkill. 

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  EXAMPLES
    SELECT a+1 FROM t1 GROUP BY a WITH ROLLUP
    SELECT SUM(a)+a FROM t1 GROUP BY a WITH ROLLUP 
    
  RETURN
    0	if ok
    1   on error
*/

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static bool change_group_ref(THD *thd, Item_func *expr, ORDER *group_list,
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                             bool *changed)
{
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  if (expr->arg_count)
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  {
    Item **arg,**arg_end;
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    bool arg_changed= FALSE;
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    for (arg= expr->arguments(),
         arg_end= expr->arguments()+expr->arg_count;
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         arg != arg_end; arg++)
    {
      Item *item= *arg;
      if (item->type() == Item::FIELD_ITEM || item->type() == Item::REF_ITEM)
      {
        ORDER *group_tmp;
        for (group_tmp= group_list; group_tmp; group_tmp= group_tmp->next)
        {
          if (item->eq(*group_tmp->item,0))
          {
            Item *new_item;    
            if(!(new_item= new Item_ref(group_tmp->item, 0, item->name)))
              return 1;                                 // fatal_error is set
            thd->change_item_tree(arg, new_item);
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            arg_changed= TRUE;
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          }
        }
      }
      else if (item->type() == Item::FUNC_ITEM)
      {
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        if (change_group_ref(thd, (Item_func *) item, group_list, &arg_changed))
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          return 1;
      }
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    }
    if (arg_changed)
    {
      expr->maybe_null= 1;
      *changed= TRUE;
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    }
  }
  return 0;
}


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/* Allocate memory needed for other rollup functions */

bool JOIN::rollup_init()
{
  uint i,j;
  Item **ref_array;

  tmp_table_param.quick_group= 0;	// Can't create groups in tmp table
  rollup.state= ROLLUP::STATE_INITED;

  /*
    Create pointers to the different sum function groups
    These are updated by rollup_make_fields()
  */
  tmp_table_param.group_parts= send_group_parts;

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  if (!(rollup.null_items= (Item_null_result**) thd->alloc((sizeof(Item*) +
                                                sizeof(Item**) +
                                                sizeof(List<Item>) +
				                ref_pointer_array_size)
				                * send_group_parts )))
9685
    return 1;
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  rollup.fields= (List<Item>*) (rollup.null_items + send_group_parts);
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  rollup.ref_pointer_arrays= (Item***) (rollup.fields + send_group_parts);
  ref_array= (Item**) (rollup.ref_pointer_arrays+send_group_parts);

  /*
    Prepare space for field list for the different levels
    These will be filled up in rollup_make_fields()
  */
  for (i= 0 ; i < send_group_parts ; i++)
  {
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    rollup.null_items[i]= new (thd->mem_root) Item_null_result();
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    List<Item> *rollup_fields= &rollup.fields[i];
    rollup_fields->empty();
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    rollup.ref_pointer_arrays[i]= ref_array;
    ref_array+= all_fields.elements;
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  }
  for (i= 0 ; i < send_group_parts; i++)
  {
9705
    for (j=0 ; j < fields_list.elements ; j++)
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      rollup.fields[i].push_back(rollup.null_items[i]);
9707
  }
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  List_iterator_fast<Item> it(all_fields);
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  Item *item;
  while ((item= it++))
  {
    ORDER *group_tmp;
    for (group_tmp= group_list; group_tmp; group_tmp= group_tmp->next)
    {
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      if (*group_tmp->item == item)
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        item->maybe_null= 1;
    }
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    if (item->type() == Item::FUNC_ITEM)
    {
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      bool changed= FALSE;
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      if (change_group_ref(thd, (Item_func *) item, group_list, &changed))
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        return 1;
      /*
        We have to prevent creation of a field in a temporary table for
        an expression that contains GROUP BY attributes.
        Marking the expression item as 'with_sum_func' will ensure this.
      */ 
      if (changed)
        item->with_sum_func= 1;
    }
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  }
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  return 0;
}
  

/*
  Fill up rollup structures with pointers to fields to use

  SYNOPSIS
    rollup_make_fields()
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    fields_arg			List of all fields (hidden and real ones)
    sel_fields			Pointer to selected fields
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    func			Store here a pointer to all fields

  IMPLEMENTATION:
    Creates copies of item_sum items for each sum level

  RETURN
    0	if ok
	In this case func is pointing to next not used element.
    1   on error
*/

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bool JOIN::rollup_make_fields(List<Item> &fields_arg, List<Item> &sel_fields,
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			      Item_sum ***func)
{
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  List_iterator_fast<Item> it(fields_arg);
  Item *first_field= sel_fields.head();
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  uint level;

  /*
    Create field lists for the different levels

    The idea here is to have a separate field list for each rollup level to
    avoid all runtime checks of which columns should be NULL.

    The list is stored in reverse order to get sum function in such an order
    in func that it makes it easy to reset them with init_sum_functions()

    Assuming:  SELECT a, b, c SUM(b) FROM t1 GROUP BY a,b WITH ROLLUP

    rollup.fields[0] will contain list where a,b,c is NULL
    rollup.fields[1] will contain list where b,c is NULL
    ...
    rollup.ref_pointer_array[#] points to fields for rollup.fields[#]
    ...
    sum_funcs_end[0] points to all sum functions
    sum_funcs_end[1] points to all sum functions, except grand totals
    ...
  */

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  for (level=0 ; level < send_group_parts ; level++)
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  {
    uint i;
    uint pos= send_group_parts - level -1;
    bool real_fields= 0;
    Item *item;
    List_iterator<Item> new_it(rollup.fields[pos]);
    Item **ref_array_start= rollup.ref_pointer_arrays[pos];
    ORDER *start_group;

    /* Point to first hidden field */
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    Item **ref_array= ref_array_start + fields_arg.elements-1;
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    /* Remember where the sum functions ends for the previous level */
    sum_funcs_end[pos+1]= *func;

    /* Find the start of the group for this level */
    for (i= 0, start_group= group_list ;
	 i++ < pos ;
	 start_group= start_group->next)
      ;

    it.rewind();
    while ((item= it++))
    {
      if (item == first_field)
      {
	real_fields= 1;				// End of hidden fields
	ref_array= ref_array_start;
      }

      if (item->type() == Item::SUM_FUNC_ITEM && !item->const_item())
      {
	/*
	  This is a top level summary function that must be replaced with
	  a sum function that is reset for this level.

	  NOTE: This code creates an object which is not that nice in a
	  sub select.  Fortunately it's not common to have rollup in
	  sub selects.
	*/
	item= item->copy_or_same(thd);
	((Item_sum*) item)->make_unique();
	if (((Item_sum*) item)->setup(thd))
	  return 1;
	*(*func)= (Item_sum*) item;
	(*func)++;
      }
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      else 
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      {
	/* Check if this is something that is part of this group by */
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	ORDER *group_tmp;
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	for (group_tmp= start_group, i= pos ;
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             group_tmp ; group_tmp= group_tmp->next, i++)
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	{
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          if (*group_tmp->item == item)
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	  {
	    /*
	      This is an element that is used by the GROUP BY and should be
	      set to NULL in this level
	    */
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            Item_null_result *null_item;
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	    item->maybe_null= 1;		// Value will be null sometimes
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            null_item= rollup.null_items[i];
            null_item->result_field= item->get_tmp_table_field();
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            item= null_item;
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	    break;
	  }
	}
      }
      *ref_array= item;
      if (real_fields)
      {
	(void) new_it++;			// Point to next item
	new_it.replace(item);			// Replace previous
	ref_array++;
      }
      else
	ref_array--;
    }
  }
  sum_funcs_end[0]= *func;			// Point to last function
  return 0;
}

/*
  Send all rollup levels higher than the current one to the client

  SYNOPSIS:
    rollup_send_data()
    idx			Level we are on:
			0 = Total sum level
			1 = First group changed  (a)
			2 = Second group changed (a,b)

  SAMPLE
    SELECT a, b, c SUM(b) FROM t1 GROUP BY a,b WITH ROLLUP

  RETURN
    0	ok
    1   If send_data_failed()
*/

int JOIN::rollup_send_data(uint idx)
{
  uint i;
  for (i= send_group_parts ; i-- > idx ; )
  {
    /* Get reference pointers to sum functions in place */
    memcpy((char*) ref_pointer_array,
	   (char*) rollup.ref_pointer_arrays[i],
	   ref_pointer_array_size);
    if ((!having || having->val_int()))
    {
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      if (send_records < unit->select_limit_cnt && do_send_rows &&
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	  result->send_data(rollup.fields[i]))
	return 1;
      send_records++;
    }
  }
  /* Restore ref_pointer_array */
  set_items_ref_array(current_ref_pointer_array);
  return 0;
}

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/*
  Write all rollup levels higher than the current one to a temp table

  SYNOPSIS:
    rollup_write_data()
    idx                 Level we are on:
                        0 = Total sum level
                        1 = First group changed  (a)
                        2 = Second group changed (a,b)
    table               reference to temp table

  SAMPLE
    SELECT a, b, SUM(c) FROM t1 GROUP BY a,b WITH ROLLUP

  RETURN
    0	ok
    1   if write_data_failed()
*/

int JOIN::rollup_write_data(uint idx, TABLE *table)
{
  uint i;
  for (i= send_group_parts ; i-- > idx ; )
  {
    /* Get reference pointers to sum functions in place */
    memcpy((char*) ref_pointer_array,
	   (char*) rollup.ref_pointer_arrays[i],
	   ref_pointer_array_size);
    if ((!having || having->val_int()))
    {
      int error;
      Item *item;
      List_iterator_fast<Item> it(rollup.fields[i]);
      while ((item= it++))
      {
        if (item->type() == Item::NULL_ITEM && item->is_result_field())
          item->save_in_result_field(1);
      }
      copy_sum_funcs(sum_funcs_end[i+1], sum_funcs_end[i]);
      if ((error= table->file->write_row(table->record[0])))
      {
	if (create_myisam_from_heap(thd, table, &tmp_table_param,
				      error, 0))
	  return 1;		     
      }
    }
  }
  /* Restore ref_pointer_array */
  set_items_ref_array(current_ref_pointer_array);
  return 0;
}

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/*
  clear results if there are not rows found for group
  (end_send_group/end_write_group)

  SYNOPSYS
     JOIN::clear()
*/

void JOIN::clear()
{
  clear_tables(this);
  copy_fields(&tmp_table_param);

  if (sum_funcs)
  {
    Item_sum *func, **func_ptr= sum_funcs;
    while ((func= *(func_ptr++)))
      func->clear();
  }
}
9979

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/****************************************************************************
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  EXPLAIN handling

9983
  Send a description about what how the select will be done to stdout
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****************************************************************************/

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static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
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			    bool distinct,const char *message)
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{
  List<Item> field_list;
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  List<Item> item_list;
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  THD *thd=join->thd;
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  select_result *result=join->result;
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  Item *item_null= new Item_null();
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  CHARSET_INFO *cs= system_charset_info;
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  DBUG_ENTER("select_describe");
9996
  DBUG_PRINT("info", ("Select 0x%lx, type %s, message %s",
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		      (ulong)join->select_lex, join->select_lex->type,
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		      message ? message : "NULL"));
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  /* Don't log this into the slow query log */
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  thd->server_status&= ~(SERVER_QUERY_NO_INDEX_USED | SERVER_QUERY_NO_GOOD_INDEX_USED);
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  join->unit->offset_limit_cnt= 0;
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  if (message)
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  {
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    item_list.push_back(new Item_int((int32)
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				     join->select_lex->select_number));
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    item_list.push_back(new Item_string(join->select_lex->type,
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					strlen(join->select_lex->type), cs));
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    for (uint i=0 ; i < 7; i++)
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      item_list.push_back(item_null);
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    item_list.push_back(new Item_string(message,strlen(message),cs));
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    if (result->send_data(item_list))
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      join->error= 1;
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  }
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  else if (join->select_lex == join->unit->fake_select_lex)
  {
    /* 
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      here we assume that the query will return at least two rows, so we
      show "filesort" in EXPLAIN. Of course, sometimes we'll be wrong
      and no filesort will be actually done, but executing all selects in
      the UNION to provide precise EXPLAIN information will hardly be
      appreciated :)
10023
    */
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    char table_name_buffer[NAME_LEN];
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    item_list.empty();
    /* id */
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    item_list.push_back(new Item_null);
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    /* select_type */
    item_list.push_back(new Item_string(join->select_lex->type,
					strlen(join->select_lex->type),
					cs));
    /* table */
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    {
      SELECT_LEX *sl= join->unit->first_select();
      uint len= 6, lastop= 0;
      memcpy(table_name_buffer, "<union", 6);
      for (; sl && len + lastop + 5 < NAME_LEN; sl= sl->next_select())
      {
        len+= lastop;
        lastop= my_snprintf(table_name_buffer + len, NAME_LEN - len,
                            "%u,", sl->select_number);
      }
      if (sl || len + lastop >= NAME_LEN)
      {
        memcpy(table_name_buffer + len, "...>", 5);
        len+= 4;
      }
      else
      {
        len+= lastop;
        table_name_buffer[len - 1]= '>';  // change ',' to '>'
      }
      item_list.push_back(new Item_string(table_name_buffer, len, cs));
    }
    /* type */
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    item_list.push_back(new Item_string(join_type_str[JT_ALL],
					  strlen(join_type_str[JT_ALL]),
					  cs));
    /* possible_keys */
    item_list.push_back(item_null);
    /* key*/
    item_list.push_back(item_null);
    /* key_len */
    item_list.push_back(item_null);
    /* ref */
    item_list.push_back(item_null);
    /* rows */
    item_list.push_back(item_null);
    /* extra */
    if (join->unit->global_parameters->order_list.first)
      item_list.push_back(new Item_string("Using filesort",
					  14, cs));
    else
      item_list.push_back(new Item_string("", 0, cs));

    if (result->send_data(item_list))
      join->error= 1;
  }
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  else
  {
    table_map used_tables=0;
    for (uint i=0 ; i < join->tables ; i++)
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    {
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      JOIN_TAB *tab=join->join_tab+i;
      TABLE *table=tab->table;
10086
      char buff[512],*buff_ptr=buff;
10087
      char buff1[512], buff2[512];
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      char table_name_buffer[NAME_LEN];
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      String tmp1(buff1,sizeof(buff1),cs);
      String tmp2(buff2,sizeof(buff2),cs);
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      tmp1.length(0);
      tmp2.length(0);

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      item_list.empty();
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      /* id */
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      item_list.push_back(new Item_uint((uint32)
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				       join->select_lex->select_number));
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      /* select_type */
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      item_list.push_back(new Item_string(join->select_lex->type,
					  strlen(join->select_lex->type),
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					  cs));
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      if (tab->type == JT_ALL && tab->select && tab->select->quick)
	tab->type= JT_RANGE;
10104
      /* table */
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      if (table->derived_select_number)
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      {
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	/* Derived table name generation */
10108
	int len= my_snprintf(table_name_buffer, sizeof(table_name_buffer)-1,
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			     "<derived%u>",
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			     table->derived_select_number);
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	item_list.push_back(new Item_string(table_name_buffer, len, cs));
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      }
      else
	item_list.push_back(new Item_string(table->table_name,
					    strlen(table->table_name),
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					    cs));
10117
      /* type */
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      item_list.push_back(new Item_string(join_type_str[tab->type],
					  strlen(join_type_str[tab->type]),
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					  cs));
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      uint j;
10122
      /* possible_keys */
10123
      if (!tab->keys.is_clear_all())
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      {
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        for (j=0 ; j < table->keys ; j++)
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        {
          if (tab->keys.is_set(j))
          {
            if (tmp1.length())
              tmp1.append(',');
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            tmp1.append(table->key_info[j].name, 
			strlen(table->key_info[j].name),
			system_charset_info);
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          }
        }
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      }
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      if (tmp1.length())
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	item_list.push_back(new Item_string(tmp1.ptr(),tmp1.length(),cs));
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      else
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	item_list.push_back(item_null);
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      /* key key_len ref */
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      if (tab->ref.key_parts)
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      {
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	KEY *key_info=table->key_info+ tab->ref.key;
	item_list.push_back(new Item_string(key_info->name,
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					    strlen(key_info->name),
					    system_charset_info));
10148
	item_list.push_back(new Item_int((int32) tab->ref.key_length));
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	for (store_key **ref=tab->ref.key_copy ; *ref ; ref++)
	{
10151 10152
	  if (tmp2.length())
	    tmp2.append(',');
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	  tmp2.append((*ref)->name(), strlen((*ref)->name()),
		      system_charset_info);
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	}
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	item_list.push_back(new Item_string(tmp2.ptr(),tmp2.length(),cs));
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      }
      else if (tab->type == JT_NEXT)
      {
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	KEY *key_info=table->key_info+ tab->index;
	item_list.push_back(new Item_string(key_info->name,
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					    strlen(key_info->name),cs));
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	item_list.push_back(new Item_int((int32) key_info->key_length));
	item_list.push_back(item_null);
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      }
      else if (tab->select && tab->select->quick)
      {
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	KEY *key_info=table->key_info+ tab->select->quick->index;
	item_list.push_back(new Item_string(key_info->name,
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					    strlen(key_info->name),cs));
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	item_list.push_back(new Item_int((int32) tab->select->quick->
					 max_used_key_length));
10173
	item_list.push_back(item_null);
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      }
      else
      {
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	item_list.push_back(item_null);
	item_list.push_back(item_null);
	item_list.push_back(item_null);
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      }
10181
      /* rows */
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      item_list.push_back(new Item_int((longlong) (ulonglong)
				       join->best_positions[i]. records_read,
				       21));
10185
      /* extra */
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      my_bool key_read=table->key_read;
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      if ((tab->type == JT_NEXT || tab->type == JT_CONST) &&
          table->used_keys.is_set(tab->index))
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	key_read=1;
10190

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      if (tab->info)
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	item_list.push_back(new Item_string(tab->info,strlen(tab->info),cs));
10193
      else
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      {
10195
	if (tab->select)
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	{
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	  if (tab->use_quick == 2)
	  {
10199
            char buf[MAX_KEY/8+1];
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	    sprintf(buff_ptr,"; Range checked for each record (index map: 0x%s)",
10201
                tab->keys.print(buf));
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	    buff_ptr=strend(buff_ptr);
	  }
	  else
	    buff_ptr=strmov(buff_ptr,"; Using where");
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	}
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	if (key_read)
	  buff_ptr= strmov(buff_ptr,"; Using index");
	if (table->reginfo.not_exists_optimize)
	  buff_ptr= strmov(buff_ptr,"; Not exists");
	if (need_tmp_table)
	{
	  need_tmp_table=0;
	  buff_ptr= strmov(buff_ptr,"; Using temporary");
	}
	if (need_order)
	{
	  need_order=0;
	  buff_ptr= strmov(buff_ptr,"; Using filesort");
	}
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	if (distinct & test_all_bits(used_tables,thd->used_tables))
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	  buff_ptr= strmov(buff_ptr,"; Distinct");
	if (buff_ptr == buff)
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	  buff_ptr+= 2;				// Skip inital "; "
	item_list.push_back(new Item_string(buff+2,(uint) (buff_ptr - buff)-2,
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					    cs));
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      }
      // For next iteration
      used_tables|=table->map;
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      if (result->send_data(item_list))
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	join->error= 1;
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    }
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  }
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  for (SELECT_LEX_UNIT *unit= join->select_lex->first_inner_unit();
       unit;
       unit= unit->next_unit())
  {
    if (mysql_explain_union(thd, unit, result))
      DBUG_VOID_RETURN;
  }
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  DBUG_VOID_RETURN;
}

10244

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int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
{
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  DBUG_ENTER("mysql_explain_union");
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  int res= 0;
  SELECT_LEX *first= unit->first_select();
10250

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  for (SELECT_LEX *sl= first;
       sl;
       sl= sl->next_select())
  {
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    // drop UNCACHEABLE_EXPLAIN, because it is for internal usage only
    uint8 uncacheable= (sl->uncacheable & ~UNCACHEABLE_EXPLAIN);
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    sl->type= (((&thd->lex->select_lex)==sl)?
	       ((thd->lex->all_selects_list != sl) ? 
		primary_key_name : "SIMPLE"):
	       ((sl == first)?
		((sl->linkage == DERIVED_TABLE_TYPE) ?
		 "DERIVED":
		 ((uncacheable & UNCACHEABLE_DEPENDENT) ?
		  "DEPENDENT SUBQUERY":
		  (uncacheable?"UNCACHEABLE SUBQUERY":
		   "SUBQUERY"))):
		((uncacheable & UNCACHEABLE_DEPENDENT) ?
		 "DEPENDENT UNION":
		 uncacheable?"UNCACHEABLE UNION":
		 "UNION")));
    sl->options|= SELECT_DESCRIBE;
  }
  if (first->next_select())
  {
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    unit->fake_select_lex->select_number= UINT_MAX; // jost for initialization
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    unit->fake_select_lex->type= "UNION RESULT";
    unit->fake_select_lex->options|= SELECT_DESCRIBE;
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    if (!(res= unit->prepare(thd, result, SELECT_NO_UNLOCK | SELECT_DESCRIBE,
                             "")))
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      res= unit->exec();
    res|= unit->cleanup();
  }
  else
  {
    thd->lex->current_select= first;
    res= mysql_select(thd, &first->ref_pointer_array,
			(TABLE_LIST*) first->table_list.first,
			first->with_wild, first->item_list,
			first->where,
			first->order_list.elements +
			first->group_list.elements,
			(ORDER*) first->order_list.first,
			(ORDER*) first->group_list.first,
			first->having,
			(ORDER*) thd->lex->proc_list.first,
			first->options | thd->options | SELECT_DESCRIBE,
			result, unit, first);
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  }
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  if (res > 0 || thd->net.report_error)
    res= -1; // mysql_explain_select do not report error
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  DBUG_RETURN(res);
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}

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void st_select_lex::print(THD *thd, String *str)
{
  if (!thd)
    thd= current_thd;

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  str->append("select ", 7);
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  //options
  if (options & SELECT_STRAIGHT_JOIN)
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    str->append("straight_join ", 14);
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  if ((thd->lex->lock_option == TL_READ_HIGH_PRIORITY) &&
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      (this == &thd->lex->select_lex))
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    str->append("high_priority ", 14);
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  if (options & SELECT_DISTINCT)
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    str->append("distinct ", 9);
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  if (options & SELECT_SMALL_RESULT)
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    str->append("sql_small_result ", 17);
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  if (options & SELECT_BIG_RESULT)
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    str->append("sql_big_result ", 15);
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  if (options & OPTION_BUFFER_RESULT)
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    str->append("sql_buffer_result ", 18);
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  if (options & OPTION_FOUND_ROWS)
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    str->append("sql_calc_found_rows ", 20);
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  if (!thd->lex->safe_to_cache_query)
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    str->append("sql_no_cache ", 13);
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  if (options & OPTION_TO_QUERY_CACHE)
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    str->append("sql_cache ", 10);
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  //Item List
  bool first= 1;
  List_iterator_fast<Item> it(item_list);
  Item *item;
  while ((item= it++))
  {
    if (first)
      first= 0;
    else
      str->append(',');
    item->print_item_w_name(str);
  }

  /*
    from clause
    TODO: support USING/FORCE/IGNORE index
  */
  if (table_list.elements)
  {
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    str->append(" from ", 6);
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    Item *next_on= 0;
    for (TABLE_LIST *table= (TABLE_LIST *) table_list.first;
	 table;
	 table= table->next)
    {
      if (table->derived)
      {
	str->append('(');
	table->derived->print(str);
	str->append(") ");
	str->append(table->alias);
      }
      else
      {
	str->append(table->db);
	str->append('.');
	str->append(table->real_name);
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	if (my_strcasecmp(table_alias_charset, table->real_name, table->alias))
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	{
	  str->append(' ');
	  str->append(table->alias);
	}
      }

      if (table->on_expr && ((table->outer_join & JOIN_TYPE_LEFT) ||
			     !(table->outer_join & JOIN_TYPE_RIGHT)))
	next_on= table->on_expr;

      if (next_on)
      {
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	str->append(" on(", 4);
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	next_on->print(str);
	str->append(')');
	next_on= 0;
      }

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      TABLE_LIST *next_table;
      if ((next_table= table->next))
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      {
	if (table->outer_join & JOIN_TYPE_RIGHT)
	{
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	  str->append(" right join ", 12);
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	  if (!(table->outer_join & JOIN_TYPE_LEFT) &&
	      table->on_expr)
	    next_on= table->on_expr;	    
	}
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	else if (next_table->straight)
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	  str->append(" straight_join ", 15);
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	else if (next_table->outer_join & JOIN_TYPE_LEFT)
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	  str->append(" left join ", 11);
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	else
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	  str->append(" join ", 6);
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      }
    }
  }

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  // Where
  Item *cur_where= where;
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  if (join)
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    cur_where= join->conds;
  if (cur_where)
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  {
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    str->append(" where ", 7);
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    cur_where->print(str);
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  }

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  // group by & olap
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  if (group_list.elements)
  {
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    str->append(" group by ", 10);
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    print_order(str, (ORDER *) group_list.first);
    switch (olap)
    {
      case CUBE_TYPE:
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	str->append(" with cube", 10);
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	break;
      case ROLLUP_TYPE:
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	str->append(" with rollup", 12);
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	break;
      default:
	;  //satisfy compiler
    }
  }

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  // having
  Item *cur_having= having;
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  if (join)
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    cur_having= join->having;
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  if (cur_having)
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  {
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    str->append(" having ", 8);
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    cur_having->print(str);
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  }

  if (order_list.elements)
  {
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    str->append(" order by ", 10);
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    print_order(str, (ORDER *) order_list.first);
  }

  // limit
  print_limit(thd, str);

  // PROCEDURE unsupported here
}
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/*
  change select_result object of JOIN

  SYNOPSIS
    JOIN::change_result()
    res		new select_result object

  RETURN
    0 - OK
    -1 - error
*/

int JOIN::change_result(select_result *res)
{
  DBUG_ENTER("JOIN::change_result");
  result= res;
  if (!procedure && result->prepare(fields_list, select_lex->master_unit()))
  {
    DBUG_RETURN(-1);
  }
  DBUG_RETURN(0);
}