From da566c16c0c03f56caa8bd6bfd9452b73ad1a456 Mon Sep 17 00:00:00 2001
From: unknown <igor@rurik.mysql.com>
Date: Wed, 26 Nov 2003 17:23:52 -0800
Subject: [PATCH] This ChangeSet Introdices Item_equal. The objects of this
class represent multiple conjunctive equalities in where conditions:
=(f1,f2,...fn) <=> f1=f2 and f2= ... and =fn. The objects are used to
generate new possibale paths to access the tables when executing a query.
They are also used to optimize the execution plan chosen by the optimizer for
the query.
sql/item.cc:
Introduced Item_equal
sql/item.h:
Introduced Item_equal.
Added traverse method.
sql/item_cmpfunc.cc:
Introduced Item_equal.
Added traverse mehtod.
sql/item_cmpfunc.h:
Itroduced Item_equal and Item_equal_iterator.
sql/item_func.cc:
Added traverse method.
Introduced Item_equal.
sql/item_func.h:
Introduced Item_equal.
Added traverse method.
sql/item_row.cc:
Added traverse method.
sql/item_row.h:
Added traverse method.
sql/item_strfunc.h:
Added traverse method.
sql/opt_range.cc:
Used Item_equal in range analysis.
sql/opt_sum.cc:
Introduced Item_equal.
sql/sql_list.h:
Added concat and disjoin methods to lists.
Fixed remove method for lists.
sql/sql_select.cc:
Introdiced Item_equal:
created Item_equal;
used Item_equal objects to generate new paths to access tables.
used Item_equal objects to optimize the execution plan chosen by optimizer.
sql/sql_select.h:
Introduced Item_equal.
---
sql/item.cc | 47 ++-
sql/item.h | 26 +-
sql/item_cmpfunc.cc | 233 ++++++++++++-
sql/item_cmpfunc.h | 63 ++++
sql/item_func.cc | 34 ++
sql/item_func.h | 8 +-
sql/item_row.cc | 12 +
sql/item_row.h | 1 +
sql/item_strfunc.h | 8 +
sql/opt_range.cc | 222 +++++++-----
sql/opt_sum.cc | 15 +
sql/sql_list.h | 34 +-
sql/sql_select.cc | 801 ++++++++++++++++++++++++++++++++++++++++++--
sql/sql_select.h | 2 +
14 files changed, 1397 insertions(+), 109 deletions(-)
diff --git a/sql/item.cc b/sql/item.cc
index 0c5b6450b4a..5091ea87bee 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -299,7 +299,8 @@ bool DTCollation::aggregate(DTCollation &dt)
return 0;
}
-Item_field::Item_field(Field *f) :Item_ident(NullS,f->table_name,f->field_name)
+Item_field::Item_field(Field *f)
+ :Item_ident(NullS,f->table_name,f->field_name), item_equal(0)
{
set_field(f);
collation.set(DERIVATION_IMPLICIT);
@@ -313,6 +314,7 @@ Item_field::Item_field(THD *thd, Item_field &item)
result_field(item.result_field)
{
collation.set(DERIVATION_IMPLICIT);
+ item_equal= item.item_equal;
}
void Item_field::set_field(Field *field_par)
@@ -969,6 +971,49 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
return 0;
}
+Item_equal *Item_field::find_item_equal(COND_EQUAL *cond_equal)
+{
+ Item_equal *item= 0;
+ while (cond_equal)
+ {
+ List_iterator_fast<Item_equal> li(cond_equal->current_level);
+ while ((item= li++))
+ {
+ if (item->contains(field))
+ return item;
+ }
+ cond_equal= cond_equal->parent_level;
+ }
+ return item;
+}
+
+Item *Item_field::equal_fields_propagator(byte *arg)
+{
+ COND_EQUAL *cond_equal= (COND_EQUAL *) arg;
+ item_equal= find_item_equal(cond_equal);
+ Item *item= 0;
+ if (item_equal)
+ item= item_equal->get_const();
+ if (item)
+ item->fixed= 0;
+ else
+ item= this;
+ return item;
+}
+
+bool Item_field::replace_equal_field_processor(byte *arg)
+{
+ if (item_equal)
+ {
+ Item_field *subst= item_equal->get_first();
+ if (subst && !field->eq(subst->field))
+ {
+ field= subst->field;
+ return 0;
+ }
+ }
+ return 0;
+}
void Item::init_make_field(Send_field *tmp_field,
enum enum_field_types field_type)
diff --git a/sql/item.h b/sql/item.h
index 0a0db619e1a..c10f7f7f9f2 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -83,6 +83,7 @@ class DTCollation {
};
typedef bool (Item::*Item_processor)(byte *arg);
+typedef Item* (Item::*Item_calculator) (byte *arg);
class Item {
Item(const Item &); /* Prevent use of these */
@@ -201,8 +202,15 @@ class Item {
return (this->*processor)(arg);
}
+ virtual Item* traverse(Item_calculator calculator, byte *arg)
+ {
+ return (this->*calculator)(arg);
+ }
+
virtual bool remove_dependence_processor(byte * arg) { return 0; }
virtual bool remove_fixed(byte * arg) { fixed= 0; return 0; }
+ virtual Item *equal_fields_propagator(byte * arg) { return this; }
+ virtual bool replace_equal_field_processor(byte * arg) { return 0; }
virtual Item *this_item() { return this; } /* For SPs mostly. */
virtual Item *this_const_item() const { return const_cast<Item*>(this); } /* For SPs mostly. */
@@ -311,17 +319,21 @@ class Item_ident :public Item
bool remove_dependence_processor(byte * arg);
};
+class Item_equal;
+class COND_EQUAL;
class Item_field :public Item_ident
{
void set_field(Field *field);
public:
Field *field,*result_field;
+ Item_equal *item_equal;
// Item_field() {}
Item_field(const char *db_par,const char *table_name_par,
const char *field_name_par)
- :Item_ident(db_par,table_name_par,field_name_par),field(0),result_field(0)
+ :Item_ident(db_par,table_name_par,field_name_par),field(0),result_field(0),
+ item_equal(0)
{ collation.set(DERIVATION_IMPLICIT); }
// Constructor need to process subselect with temporary tables (see Item)
Item_field(THD *thd, Item_field &item);
@@ -355,6 +367,9 @@ class Item_field :public Item_ident
bool get_time(TIME *ltime);
bool is_null() { return field->is_null(); }
Item *get_tmp_table_item(THD *thd);
+ Item_equal *find_item_equal(COND_EQUAL *cond_equal);
+ Item *equal_fields_propagator(byte *arg);
+ bool replace_equal_field_processor(byte *arg);
friend class Item_default_value;
friend class Item_insert_value;
};
@@ -897,6 +912,15 @@ class Item_default_value : public Item_field
return arg->walk(processor, args) ||
(this->*processor)(args);
}
+
+ Item *traverse(Item_calculator calculator, byte *args)
+ {
+ Item *new_item= arg->traverse(calculator, args);
+ if (!new_item)
+ return 0;
+ arg= new_item;
+ return (this->*calculator)(args);
+ }
};
class Item_insert_value : public Item_field
diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 1629ed6aa80..76cec7b6615 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -225,7 +225,7 @@ void Item_bool_func2::fix_length_and_dec()
}
// Make a special case of compare with fields to get nicer DATE comparisons
- if (args[0]->type() == FIELD_ITEM)
+ if (args[0]->type() == FIELD_ITEM && !args[0]->const_item())
{
Field *field=((Item_field*) args[0])->field;
if (field->store_for_compare())
@@ -238,7 +238,7 @@ void Item_bool_func2::fix_length_and_dec()
}
}
}
- if (args[1]->type() == FIELD_ITEM)
+ if (args[1]->type() == FIELD_ITEM && !args[1]->const_item())
{
Field *field=((Item_field*) args[1])->field;
if (field->store_for_compare())
@@ -1712,6 +1712,21 @@ bool Item_cond::walk(Item_processor processor, byte *arg)
return Item_func::walk(processor, arg);
}
+Item *Item_cond::traverse(Item_calculator calculator, byte *arg)
+{
+ List_iterator<Item> li(list);
+ Item *item;
+ while ((item= li++))
+ {
+ Item *new_item= item->traverse(calculator, arg);
+ if (!new_item)
+ return 0;
+ if (new_item != item)
+ li.replace(new_item);
+ }
+ return Item_func::traverse(calculator, arg);
+}
+
void Item_cond::split_sum_func(Item **ref_pointer_array, List<Item> &fields)
{
List_iterator<Item> li(list);
@@ -2499,3 +2514,217 @@ Item *Item_cond_or::neg_transformer() /* NOT(a OR b OR ...) -> */
neg_arguments();
return new Item_cond_and(list);
}
+
+Item_equal::Item_equal(Item_field *f1, Item_field *f2)
+ : Item_bool_func(), const_item(0), eval_item(0), cond_false(0)
+{
+ const_item_cache= 0;
+ fields.push_back(f1);
+ fields.push_back(f2);
+}
+
+Item_equal::Item_equal(Item *c, Item_field *f)
+ : Item_bool_func(), eval_item(0), cond_false(0)
+{
+ const_item_cache= 0;
+ fields.push_back(f);
+ const_item= c;
+}
+
+Item_equal::Item_equal(Item_equal *item_equal)
+ : Item_bool_func(), eval_item(0), cond_false(0)
+{
+ const_item_cache= 0;
+ List_iterator_fast<Item_field> li(item_equal->fields);
+ Item_field *item;
+ while ((item= li++))
+ {
+ fields.push_back(item);
+ }
+ const_item= item_equal->const_item;
+ cond_false= item_equal->cond_false;
+}
+
+void Item_equal::add(Item *c)
+{
+ if (cond_false)
+ return;
+ if (!const_item)
+ {
+ const_item= c;
+ return;
+ }
+ Item_func_eq *func= new Item_func_eq(c, const_item);
+ func->set_cmp_func();
+ cond_false = !(func->val_int());
+}
+
+void Item_equal::add(Item_field *f)
+{
+ fields.push_back(f);
+}
+
+bool Item_equal::contains(Field *field)
+{
+ List_iterator_fast<Item_field> it(fields);
+ Item_field *item;
+ while ((item= it++))
+ {
+ if (field->eq(item->field))
+ return 1;
+ }
+ return 0;
+}
+
+void Item_equal::merge(Item_equal *item)
+{
+ fields.concat(&item->fields);
+ Item *c= item->const_item;
+ if (c)
+ {
+ /*
+ The flag cond_false will be set to 1 after this, if
+ the multiple equality already contains a constant and its
+ value is not equal to the value of c.
+ */
+ add(const_item);
+ }
+ cond_false|= item->cond_false;
+}
+
+void Item_equal::sort(void *table_join_idx)
+{
+ bool swap;
+ void **idx= (void **) table_join_idx;
+ List_iterator<Item_field> it(fields);
+ do
+ {
+ Item_field *item1= it++;
+ Item_field **ref1= it.ref();
+ Item_field *item2;
+ Item_field **ref2;
+
+ if (!item1)
+ break;
+ swap= FALSE;
+ while ((item2= it++))
+ {
+ ref2= it.ref();
+ if (idx[item1->field->table->tablenr] >
+ idx[item2->field->table->tablenr])
+ {
+ Item_field *item= *ref1;
+ *ref1= *ref2;
+ *ref2= item;
+ swap= TRUE;
+ }
+ else
+ {
+ item1= item2;
+ ref1= ref2;
+ }
+ }
+ it.rewind();
+ } while (swap);
+}
+
+bool Item_equal::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
+{
+ List_iterator_fast<Item_field> li(fields);
+ Item *item;
+ not_null_tables_cache= used_tables_cache= 0;
+ const_item_cache= 0;
+ while ((item=li++))
+ {
+ table_map tmp_table_map;
+ used_tables_cache|= item->used_tables();
+ tmp_table_map= item->not_null_tables();
+ not_null_tables_cache|= tmp_table_map;
+ if (item->maybe_null)
+ maybe_null=1;
+ }
+ fix_length_and_dec();
+ fixed= 1;
+ return 0;
+}
+
+void Item_equal::update_used_tables()
+{
+ List_iterator_fast<Item_field> li(fields);
+ Item *item;
+ not_null_tables_cache= used_tables_cache= 0;
+ while ((item=li++))
+ {
+ item->update_used_tables();
+ used_tables_cache|= item->used_tables();
+ const_item_cache&= item->const_item();
+ }
+}
+
+longlong Item_equal::val_int()
+{
+ if (cond_false)
+ return 0;
+ List_iterator_fast<Item_field> it(fields);
+ Item *item= const_item ? const_item : it++;
+ if ((null_value= item->null_value))
+ return 0;
+ eval_item->store_value(item);
+ while((item= it++))
+ {
+ if ((null_value= item->null_value) || eval_item->cmp(item))
+ return 0;
+ }
+ return 1;
+}
+
+void Item_equal::fix_length_and_dec()
+{
+ Item *item= const_item ? const_item : get_first();
+ eval_item= cmp_item::get_comparator(item);
+ if (item->result_type() == STRING_RESULT)
+ eval_item->cmp_charset= cmp_collation.collation;
+}
+
+bool Item_equal::walk(Item_processor processor, byte *arg)
+{
+ List_iterator_fast<Item_field> it(fields);
+ Item *item;
+ while ((item= it++))
+ if (item->walk(processor, arg))
+ return 1;
+ return Item_func::walk(processor, arg);
+}
+
+Item *Item_equal::traverse(Item_calculator calculator, byte *arg)
+{
+ List_iterator<Item_field> it(fields);
+ Item *item;
+ while ((item= it++))
+ {
+ Item *new_item= item->traverse(calculator, arg);
+ if (!new_item)
+ return 0;
+ if (new_item != item)
+ it.replace((Item_field *) new_item);
+ }
+ return Item_func::traverse(calculator, arg);
+}
+
+void Item_equal::print(String *str)
+{
+ str->append(func_name());
+ str->append('(');
+ List_iterator_fast<Item_field> it(fields);
+ Item *item;
+ if ((item= it++))
+ item->print(str);
+ while ((item= it++))
+ {
+ str->append(',');
+ str->append(' ');
+ item->print(str);
+ }
+ str->append(')');
+}
+
diff --git a/sql/item_cmpfunc.h b/sql/item_cmpfunc.h
index dac7a2d43eb..cf14fbc17ea 100644
--- a/sql/item_cmpfunc.h
+++ b/sql/item_cmpfunc.h
@@ -908,13 +908,76 @@ class Item_cond :public Item_bool_func
void top_level_item() { abort_on_null=1; }
void copy_andor_arguments(THD *thd, Item_cond *item);
bool walk(Item_processor processor, byte *arg);
+ Item *traverse(Item_calculator calculator, byte *arg);
void neg_arguments();
};
+class Item_equal: public Item_bool_func
+{
+ List<Item_field> fields; /* list of equal field items */
+ Item *const_item; /* optional constant item equal to fields items */
+ cmp_item *eval_item;
+ bool cond_false;
+ DTCollation cmp_collation;
+public:
+ inline Item_equal()
+ : Item_bool_func(), const_item(0), eval_item(0), cond_false(0)
+ { const_item_cache=0 ;}
+ Item_equal(Item_field *f1, Item_field *f2);
+ Item_equal(Item *c, Item_field *f);
+ Item_equal(Item_equal *item_equal);
+ inline Item* get_const() { return const_item; }
+ void add(Item *c);
+ void add(Item_field *f);
+ bool is_false() { return cond_false; }
+ bool contains(Field *field);
+ Item_field* get_first() { return fields.head(); }
+ void merge(Item_equal *item);
+ enum Functype functype() const { return MULT_EQUAL_FUNC; }
+ longlong val_int();
+ const char *func_name() const { return "multiple equal"; }
+ optimize_type select_optimize() const { return OPTIMIZE_EQUAL; }
+ void sort(void *table_join_idx);
+ friend class Item_equal_iterator;
+ void fix_length_and_dec();
+ bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref);
+ void update_used_tables();
+ bool walk(Item_processor processor, byte *arg);
+ Item *traverse(Item_calculator calculator, byte *arg);
+ void print(String *str);
+};
+
+class COND_EQUAL
+{
+public:
+ COND_EQUAL *parent_level;
+ List<Item_equal> current_level;
+ COND_EQUAL() { parent_level= 0; }
+};
+
+
+class Item_equal_iterator :List_iterator_fast<Item_field>
+{
+public:
+ inline Item_equal_iterator(Item_equal &item_equal)
+ :List_iterator_fast<Item_field> (item_equal.fields)
+ {}
+ inline Item_field* operator++(int)
+ {
+ Item_field *item= (*(List_iterator_fast<Item_field> *) this)++;
+ return item;
+ }
+ inline void rewind(void)
+ {
+ List_iterator_fast<Item_field>::rewind();
+ }
+};
+
class Item_cond_and :public Item_cond
{
public:
+ COND_EQUAL cond_equal;
Item_cond_and() :Item_cond() {}
Item_cond_and(Item *i1,Item *i2) :Item_cond(i1,i2) {}
Item_cond_and(THD *thd, Item_cond_and &item) :Item_cond(thd, item) {}
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 7e03f8c9c45..4337ee631f4 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -242,6 +242,40 @@ bool Item_func::walk (Item_processor processor, byte *argument)
return (this->*processor)(argument);
}
+Item *Item_func::traverse(Item_calculator calculator, byte *argument)
+{
+ if (arg_count)
+ {
+ Item **arg,**arg_end;
+ for (arg= args, arg_end= args+arg_count; arg != arg_end; arg++)
+ {
+ Item *new_item= (*arg)->traverse(calculator, argument);
+ if (!new_item)
+ return 0;
+ *arg= new_item;
+ }
+ }
+ return (this->*calculator)(argument);
+}
+
+Item *Item_func::equal_fields_propagator(byte *argument)
+{
+ if (arg_count)
+ {
+ Item **arg,**arg_end;
+ for (arg= args, arg_end= args+arg_count; arg != arg_end; arg++)
+ {
+ if (!(*arg)->fixed)
+ {
+ fix_fields(current_thd, 0, 0);
+ break;
+ }
+ }
+ }
+ return this;
+}
+
+
void Item_func::split_sum_func(Item **ref_pointer_array, List<Item> &fields)
{
Item **arg, **arg_end;
diff --git a/sql/item_func.h b/sql/item_func.h
index d3cfaf63b5a..f92eea1bc94 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -40,7 +40,8 @@ class Item_func :public Item_result_field
enum Functype { UNKNOWN_FUNC,EQ_FUNC,EQUAL_FUNC,NE_FUNC,LT_FUNC,LE_FUNC,
GE_FUNC,GT_FUNC,FT_FUNC,
LIKE_FUNC,NOTLIKE_FUNC,ISNULL_FUNC,ISNOTNULL_FUNC,
- COND_AND_FUNC, COND_OR_FUNC, COND_XOR_FUNC, BETWEEN, IN_FUNC,
+ COND_AND_FUNC, COND_OR_FUNC, COND_XOR_FUNC,
+ BETWEEN, IN_FUNC, MULT_EQUAL_FUNC,
INTERVAL_FUNC, ISNOTNULLTEST_FUNC,
SP_EQUALS_FUNC, SP_DISJOINT_FUNC,SP_INTERSECTS_FUNC,
SP_TOUCHES_FUNC,SP_CROSSES_FUNC,SP_WITHIN_FUNC,
@@ -49,7 +50,8 @@ class Item_func :public Item_result_field
SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
NOT_FUNC, NOT_ALL_FUNC,
GUSERVAR_FUNC};
- enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL };
+ enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL,
+ OPTIMIZE_EQUAL };
enum Type type() const { return FUNC_ITEM; }
virtual enum Functype functype() const { return UNKNOWN_FUNC; }
Item_func(void):
@@ -146,6 +148,8 @@ class Item_func :public Item_result_field
bool agg_arg_collations_for_comparison(DTCollation &c, Item **items, uint nitems);
bool walk(Item_processor processor, byte *arg);
+ Item *traverse(Item_calculator calculator, byte *arg);
+ Item *equal_fields_propagator(byte *arg);
};
diff --git a/sql/item_row.cc b/sql/item_row.cc
index 89b38c8a753..d7afe9ad5f0 100644
--- a/sql/item_row.cc
+++ b/sql/item_row.cc
@@ -140,6 +140,18 @@ bool Item_row::walk(Item_processor processor, byte *arg)
return (this->*processor)(arg);
}
+Item *Item_row::traverse(Item_calculator calculator, byte *arg)
+{
+ for (uint i= 0; i < arg_count; i++)
+ {
+ Item *new_item= items[i]->traverse(calculator, arg);
+ if (!new_item)
+ return 0;
+ items[i]= new_item;
+ }
+ return (this->*calculator)(arg);
+}
+
void Item_row::bring_value()
{
for (uint i= 0; i < arg_count; i++)
diff --git a/sql/item_row.h b/sql/item_row.h
index a09bd1a2c31..de6c18bf0d9 100644
--- a/sql/item_row.h
+++ b/sql/item_row.h
@@ -71,6 +71,7 @@ class Item_row: public Item
void print(String *str);
bool walk(Item_processor processor, byte *arg);
+ Item *traverse(Item_calculator calculator, byte *arg);
uint cols() { return arg_count; }
Item* el(uint i) { return items[i]; }
diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index a7949511f02..f628160d868 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -427,6 +427,14 @@ class Item_func_make_set :public Item_str_func
return item->walk(processor, arg) ||
Item_str_func::walk(processor, arg);
}
+ Item *traverse(Item_calculator calculator, byte *arg)
+ {
+ Item *new_item= item->traverse(calculator, arg);
+ if (!new_item)
+ return 0;
+ item= new_item;
+ return Item_str_func::traverse(calculator, arg);
+ }
void print(String *str);
};
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index e2761832e65..4626bffc3e2 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -762,11 +762,72 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
DBUG_RETURN(records ? test(quick) : -1);
}
+static SEL_TREE *get_func_mm_tree(PARAM *param, Item_func *cond_func,
+ Field *field, Item *value,
+ Item_result cmp_type)
+{
+ SEL_TREE *tree= 0;
+ DBUG_ENTER("get_func_mm_tree");
+
+ if (cond_func->functype() == Item_func::NE_FUNC)
+ {
+
+ tree= get_mm_parts(param, field, Item_func::LT_FUNC,
+ value, cmp_type);
+ if (tree)
+ {
+ tree= tree_or(param, tree, get_mm_parts(param, field,
+ Item_func::GT_FUNC,
+ value, cmp_type));
+ }
+ }
+ else if (cond_func->functype() == Item_func::BETWEEN)
+ {
+
+ tree= get_mm_parts(param, field, Item_func::GE_FUNC,
+ cond_func->arguments()[1],cmp_type);
+ if (tree)
+ {
+ tree= tree_and(param, tree, get_mm_parts(param, field,
+ Item_func::LE_FUNC,
+ cond_func->arguments()[2],
+ cmp_type));
+ }
+ }
+ else if (cond_func->functype() == Item_func::IN_FUNC)
+ {
+ Item_func_in *func=(Item_func_in*) cond_func;
+ tree= get_mm_parts(param, field, Item_func::EQ_FUNC,
+ func->arguments()[1], cmp_type);
+ if (tree)
+ {
+ for (uint i =2 ; i < func->argument_count() ; i++)
+ {
+ tree= tree_or(param, tree, get_mm_parts(param, field,
+ Item_func::EQ_FUNC,
+ func->arguments()[i],
+ cmp_type));
+ }
+ }
+ }
+ else
+ {
+ Item_func::Functype func_type=
+ (value != cond_func->arguments()[0]) ? cond_func->functype() :
+ ((Item_bool_func2*) cond_func)->rev_functype();
+ tree= get_mm_parts(param, field, func_type, value, cmp_type);
+ }
+ DBUG_RETURN(tree);
+}
+
/* make a select tree of all keys in condition */
static SEL_TREE *get_mm_tree(PARAM *param,COND *cond)
{
SEL_TREE *tree=0;
+ SEL_TREE *ftree= 0;
+ Item_field *field_item= 0;
+ Item *value;
DBUG_ENTER("get_mm_tree");
if (cond->type() == Item::COND_ITEM)
@@ -814,9 +875,12 @@ static SEL_TREE *get_mm_tree(PARAM *param,COND *cond)
DBUG_RETURN(new SEL_TREE(SEL_TREE::IMPOSSIBLE));
}
- table_map ref_tables=cond->used_tables();
+ table_map ref_tables= 0;
+ table_map param_comp= ~(param->prev_tables | param->read_tables |
+ param->current_table);
if (cond->type() != Item::FUNC_ITEM)
{ // Should be a field
+ ref_tables= cond->used_tables();
if ((ref_tables & param->current_table) ||
(ref_tables & ~(param->prev_tables | param->read_tables)))
DBUG_RETURN(0);
@@ -828,76 +892,98 @@ static SEL_TREE *get_mm_tree(PARAM *param,COND *cond)
DBUG_RETURN(0); // Can't be calculated
if (cond_func->functype() == Item_func::BETWEEN)
- {
+ {
if (cond_func->arguments()[0]->type() == Item::FIELD_ITEM)
{
- Field *field=((Item_field*) (cond_func->arguments()[0]))->field;
- Item_result cmp_type=field->cmp_type();
- DBUG_RETURN(tree_and(param,
- get_mm_parts(param, field,
- Item_func::GE_FUNC,
- cond_func->arguments()[1], cmp_type),
- get_mm_parts(param, field,
- Item_func::LE_FUNC,
- cond_func->arguments()[2], cmp_type)));
+ field_item= (Item_field*) (cond_func->arguments()[0]);
+ value= NULL;
}
- DBUG_RETURN(0);
+ else
+ DBUG_RETURN(0);
}
- if (cond_func->functype() == Item_func::IN_FUNC)
- { // COND OR
+ else if (cond_func->functype() == Item_func::IN_FUNC)
+ {
Item_func_in *func=(Item_func_in*) cond_func;
if (func->key_item()->type() == Item::FIELD_ITEM)
{
- Field *field=((Item_field*) (func->key_item()))->field;
- Item_result cmp_type=field->cmp_type();
- tree= get_mm_parts(param,field,Item_func::EQ_FUNC,
- func->arguments()[1],cmp_type);
- if (!tree)
- DBUG_RETURN(tree); // Not key field
- for (uint i=2 ; i < func->argument_count(); i++)
+ field_item= (Item_field*) (func->key_item());
+ value= NULL;
+ }
+ else
+ DBUG_RETURN(0);
+ }
+ else if (cond_func->functype() == Item_func::MULT_EQUAL_FUNC)
+ {
+ Item_equal *item_equal= (Item_equal *) cond;
+ Item_equal_iterator it(*item_equal);
+ if (!(value= item_equal->get_const()))
+ value= it++;
+ while (value)
+ {
+ ref_tables= value->used_tables();
+ Item_equal_iterator li(*item_equal);
+ while ((field_item= li++))
{
- SEL_TREE *new_tree=get_mm_parts(param,field,Item_func::EQ_FUNC,
- func->arguments()[i],cmp_type);
- tree=tree_or(param,tree,new_tree);
+ if (field_item != value)
+ {
+ Field *field= field_item->field;
+ Item_result cmp_type= field->cmp_type();
+ if (!((ref_tables | field->table->map) & param_comp))
+ {
+ tree= get_mm_parts(param, field, Item_func::EQ_FUNC,
+ value,cmp_type);
+ ftree= !ftree ? tree : tree_and(param, ftree, tree);
+ }
+ }
}
- DBUG_RETURN(tree);
- }
- DBUG_RETURN(0); // Can't optimize this IN
- }
-
- if (ref_tables & ~(param->prev_tables | param->read_tables |
- param->current_table))
- DBUG_RETURN(0); // Can't be calculated yet
- if (!(ref_tables & param->current_table))
- DBUG_RETURN(new SEL_TREE(SEL_TREE::MAYBE)); // This may be false or true
-
- /* check field op const */
- /* btw, ft_func's arguments()[0] isn't FIELD_ITEM. SerG*/
- if (cond_func->arguments()[0]->type() == Item::FIELD_ITEM)
- {
- tree= get_mm_parts(param,
- ((Item_field*) (cond_func->arguments()[0]))->field,
- cond_func->functype(),
- cond_func->arg_count > 1 ? cond_func->arguments()[1] :
- 0,
- ((Item_field*) (cond_func->arguments()[0]))->field->
- cmp_type());
- }
- /* check const op field */
- if (!tree &&
- cond_func->have_rev_func() &&
- cond_func->arguments()[1]->type() == Item::FIELD_ITEM)
- {
- DBUG_RETURN(get_mm_parts(param,
- ((Item_field*)
- (cond_func->arguments()[1]))->field,
- ((Item_bool_func2*) cond_func)->rev_functype(),
- cond_func->arguments()[0],
- ((Item_field*)
- (cond_func->arguments()[1]))->field->cmp_type()
- ));
+ if (item_equal->get_const())
+ break;
+ value= it++;
+ }
+ DBUG_RETURN(ftree);
}
- DBUG_RETURN(tree);
+ else if (cond_func->arguments()[0]->type() == Item::FIELD_ITEM)
+ {
+ field_item= (Item_field*) (cond_func->arguments()[0]);
+ value= cond_func->arg_count > 1 ? cond_func->arguments()[1] : 0;
+ }
+ else if (cond_func->have_rev_func() &&
+ cond_func->arguments()[1]->type() == Item::FIELD_ITEM)
+ {
+ field_item= (Item_field*) (cond_func->arguments()[1]);
+ value= cond_func->arguments()[0];
+ }
+ else
+ DBUG_RETURN(0);
+
+ for (uint i= 0; i < cond_func->arg_count; i++)
+ {
+ Item *arg= cond_func->arguments()[i];
+ if (arg != field_item)
+ ref_tables|= arg->used_tables();
+ }
+ Field *field= field_item->field;
+ Item_result cmp_type= field->cmp_type();
+ if (!((ref_tables | field->table->map) & param_comp))
+ ftree= get_func_mm_tree(param, cond_func, field, value, cmp_type);
+ Item_equal *item_equal= field_item->item_equal;
+ if (item_equal)
+ {
+ Item_equal_iterator it(*item_equal);
+ Item_field *item;
+ while ((item= it++))
+ {
+ Field *f= item->field;
+ if (field->eq(f))
+ continue;
+ if (!((ref_tables | f->table->map) & param_comp))
+ {
+ tree= get_func_mm_tree(param, cond_func, f, value, cmp_type);
+ ftree= !ftree ? tree : tree_and(param, ftree, tree);
+ }
+ }
+ }
+ DBUG_RETURN(ftree);
}
@@ -905,17 +991,10 @@ static SEL_TREE *
get_mm_parts(PARAM *param, Field *field, Item_func::Functype type,
Item *value, Item_result cmp_type)
{
- bool ne_func= FALSE;
DBUG_ENTER("get_mm_parts");
if (field->table != param->table)
DBUG_RETURN(0);
- if (type == Item_func::NE_FUNC)
- {
- ne_func= TRUE;
- type= Item_func::LT_FUNC;
- }
-
KEY_PART *key_part = param->key_parts;
KEY_PART *end = param->key_parts_end;
SEL_TREE *tree=0;
@@ -951,13 +1030,6 @@ get_mm_parts(PARAM *param, Field *field, Item_func::Functype type,
}
}
- if (ne_func)
- {
- SEL_TREE *tree2= get_mm_parts(param, field, Item_func::GT_FUNC,
- value, cmp_type);
- if (tree2)
- tree= tree_or(param,tree,tree2);
- }
DBUG_RETURN(tree);
}
diff --git a/sql/opt_sum.cc b/sql/opt_sum.cc
index 932aceebdbb..ce650701347 100644
--- a/sql/opt_sum.cc
+++ b/sql/opt_sum.cc
@@ -352,6 +352,18 @@ static bool simple_pred(Item_func *func_item, Item **args, bool *inv_order)
Item *item;
*inv_order= 0;
switch (func_item->argument_count()) {
+ case 0:
+ /* MULT_EQUAL_FUNC */
+ {
+ Item_equal *item_equal= (Item_equal *) func_item;
+ Item_equal_iterator it(*item_equal);
+ args[0]= it++;
+ if (it++)
+ return 0;
+ if (!(args[1]= item_equal->get_const()))
+ return 0;
+ }
+ break;
case 1:
/* field IS NULL */
item= func_item->arguments()[0];
@@ -492,6 +504,9 @@ static bool matching_cond(bool max_fl, TABLE_REF *ref, KEY *keyinfo,
case Item_func::BETWEEN:
between= 1;
break;
+ case Item_func::MULT_EQUAL_FUNC:
+ eq_type= 1;
+ break;
default:
return 0; // Can't optimize function
}
diff --git a/sql/sql_list.h b/sql/sql_list.h
index 7200046e6c5..d7a62b7fd7d 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -121,10 +121,12 @@ class base_list :public Sql_alloc
void remove(list_node **prev)
{
list_node *node=(*prev)->next;
- delete *prev;
- *prev=node;
if (!--elements)
last= &first;
+ else if (last == &(*prev)->next)
+ last= prev;
+ delete *prev;
+ *prev=node;
}
inline void *pop(void)
{
@@ -135,6 +137,30 @@ class base_list :public Sql_alloc
last= &first;
return tmp->info;
}
+ inline void concat(base_list *list)
+ {
+ if (!list->is_empty())
+ {
+ *last= list->first;
+ last= list->last;
+ elements+= list->elements;
+ }
+ }
+ inline void disjoin(base_list *list)
+ {
+ list_node **prev= &first;
+ list_node *node= first;
+ list_node *list_first= list->first;
+ elements=0;
+ while (node && node != list_first)
+ {
+ prev= &node->next;
+ node= node->next;
+ elements++;
+ }
+ *prev= *last;
+ last= prev;
+ }
inline list_node* last_node() { return *last; }
inline list_node* first_node() { return first;}
inline void *head() { return first->info; }
@@ -245,6 +271,8 @@ template <class T> class List :public base_list
inline T* head() {return (T*) base_list::head(); }
inline T** head_ref() {return (T**) base_list::head_ref(); }
inline T* pop() {return (T*) base_list::pop(); }
+ inline void concat(List<T> *list) { return base_list::concat(list); }
+ inline void disjoin(List<T> *list) { return base_list::disjoin(list); }
void delete_elements(void)
{
list_node *element,*next;
@@ -265,6 +293,8 @@ template <class T> class List_iterator :public base_list_iterator
inline T* operator++(int) { return (T*) base_list_iterator::next(); }
inline T *replace(T *a) { return (T*) base_list_iterator::replace(a); }
inline T *replace(List<T> &a) { return (T*) base_list_iterator::replace(a); }
+ inline void rewind(void) { base_list_iterator::rewind(); }
+ inline void remove() { base_list_iterator::remove(); }
inline void after(T *a) { base_list_iterator::after(a); }
inline T** ref(void) { return (T**) base_list_iterator::ref(); }
};
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index eea5ed72a3a..7c0464bec05 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -72,6 +72,11 @@ static int return_zero_rows(JOIN *join, select_result *res,TABLE_LIST *tables,
uint select_options, const char *info,
Item *having, Procedure *proc,
SELECT_LEX_UNIT *unit);
+static Item *flatten_condition(COND *cond);
+static COND *build_all_equal_items(COND *cond,
+ COND_EQUAL *inherited);
+static COND* substitute_for_best_equal_field(COND *cond,
+ void *table_join_idx);
static COND *optimize_cond(COND *conds,Item::cond_result *cond_value);
static COND *remove_eq_conds(COND *cond,Item::cond_result *cond_value);
static bool const_expression_in_where(COND *conds,Item *item, Item **comp_item);
@@ -526,6 +531,56 @@ JOIN::optimize()
}
#endif
+ /* eliminate NOT operators */
+ conds= eliminate_not_funcs(conds);
+ DBUG_EXECUTE("where", print_where(conds, "after negation elimination"););
+
+ /* Eliminate nested AND/OR in conditions */
+ if (conds)
+ conds= flatten_condition(conds);
+ {
+ TABLE_LIST *tables;
+ for (tables= tables_list; tables; tables= tables->next)
+ {
+ if (tables->on_expr)
+ tables->on_expr= flatten_condition(tables->on_expr);
+ }
+ }
+
+ /*
+ Build all multiple equality predicates and eliminate equality
+ predicates that can be inferred from these multiple equalities.
+ For each reference of a field included into a multiple equality
+ that occurs in a function set a pointer to the multiple equality
+ predicate. Substitute a constant instead of this field if the
+ multiple equality contains a constant.
+ */
+ if (conds)
+ {
+ conds= build_all_equal_items(conds, NULL);
+ conds->update_used_tables();
+ if (conds->type() == Item::COND_ITEM &&
+ ((Item_cond*) conds)->functype() == Item_func::COND_AND_FUNC)
+ cond_equal= &((Item_cond_and*) conds)->cond_equal;
+ else if (conds->type() == Item::FUNC_ITEM &&
+ ((Item_cond*) conds)->functype() == Item_func::MULT_EQUAL_FUNC)
+ {
+ cond_equal= new COND_EQUAL;
+ cond_equal->current_level.push_back((Item_equal *) conds);
+ }
+ }
+ {
+ TABLE_LIST *tables;
+ for (tables= tables_list; tables; tables= tables->next)
+ {
+ if (tables->on_expr)
+ {
+ tables->on_expr= build_all_equal_items(tables->on_expr, cond_equal);
+ tables->on_expr->update_used_tables();
+ }
+ }
+ }
+
conds= optimize_cond(conds,&cond_value);
if (thd->net.report_error)
{
@@ -626,6 +681,30 @@ JOIN::optimize()
}
mysql_unlock_some_tables(thd, this->table, const_tables);
}
+ /*
+ Among the equal fields belonging to the same multiple equality
+ choose the one that is to be retrieved first and substitute
+ all references to these in where condition for a reference for
+ the selected field.
+ */
+ if (conds)
+ {
+ conds= substitute_for_best_equal_field(conds, map2table);
+ conds->update_used_tables();
+ }
+ {
+ TABLE_LIST *tables;
+ for (tables= tables_list; tables; tables= tables->next)
+ {
+ if (tables->on_expr)
+ {
+ tables->on_expr= substitute_for_best_equal_field(tables->on_expr,
+ map2table);
+ tables->on_expr->update_used_tables();
+ map2table[tables->table->tablenr]->on_expr= tables->on_expr;
+ }
+ }
+ }
if (!conds && outer_join)
{
/* Handle the case where we have an OUTER JOIN without a WHERE */
@@ -2202,6 +2281,35 @@ add_key_field(KEY_FIELD **key_fields,uint and_level,
}
+static void
+add_key_equal_fields(KEY_FIELD **key_fields, uint and_level,
+ Item_field *field_item,
+ bool eq_func, Item **val,
+ uint num_values, table_map usable_tables)
+{
+ Field *field= field_item->field;
+ add_key_field(key_fields, and_level, field,
+ eq_func, val, num_values, usable_tables);
+ Item_equal *item_equal= field_item->item_equal;
+ if (item_equal)
+ {
+ /*
+ Add to the set of possible key values every substitution of
+ the field for an equal field included into item_equal
+ */
+ Item_equal_iterator it(*item_equal);
+ Item_field *item;
+ while ((item= it++))
+ {
+ if (!field->eq(item->field))
+ {
+ add_key_field(key_fields, and_level, item->field,
+ eq_func, val, num_values, usable_tables);
+ }
+ }
+ }
+}
+
static void
add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
COND *cond, table_map usable_tables)
@@ -2247,11 +2355,11 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
// BETWEEN or IN
if (cond_func->key_item()->real_item()->type() == Item::FIELD_ITEM &&
!(cond_func->used_tables() & OUTER_REF_TABLE_BIT))
- add_key_field(key_fields,*and_level,
- ((Item_field*) (cond_func->key_item()->real_item()))->
- field, 0,
- cond_func->arguments()+1, cond_func->argument_count()-1,
- usable_tables);
+ add_key_equal_fields(key_fields,*and_level,
+ (Item_field*) (cond_func->key_item()->real_item()),
+ 0, cond_func->arguments()+1,
+ cond_func->argument_count()-1,
+ usable_tables);
break;
case Item_func::OPTIMIZE_OP:
{
@@ -2261,21 +2369,19 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM &&
!(cond_func->arguments()[0]->used_tables() & OUTER_REF_TABLE_BIT))
{
- add_key_field(key_fields,*and_level,
- ((Item_field*) (cond_func->arguments()[0])->real_item())
- ->field,
- equal_func,
- cond_func->arguments()+1, 1, usable_tables);
+ add_key_equal_fields(key_fields, *and_level,
+ (Item_field*) (cond_func->arguments()[0])->real_item(),
+ equal_func,
+ cond_func->arguments()+1, 1, usable_tables);
}
if (cond_func->arguments()[1]->real_item()->type() == Item::FIELD_ITEM &&
cond_func->functype() != Item_func::LIKE_FUNC &&
!(cond_func->arguments()[1]->used_tables() & OUTER_REF_TABLE_BIT))
{
- add_key_field(key_fields,*and_level,
- ((Item_field*) (cond_func->arguments()[1])->real_item())
- ->field,
- equal_func,
- cond_func->arguments(),1,usable_tables);
+ add_key_equal_fields(key_fields,*and_level,
+ (Item_field*) (cond_func->arguments()[1])->real_item(),
+ equal_func,
+ cond_func->arguments(),1,usable_tables);
}
break;
}
@@ -2287,15 +2393,55 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
Item *tmp=new Item_null;
if (!tmp) // Should never be true
return;
- add_key_field(key_fields,*and_level,
- ((Item_field*) (cond_func->arguments()[0])->real_item())
- ->field,
+ add_key_equal_fields(key_fields,*and_level,
+ (Item_field*) (cond_func->arguments()[0])->real_item(),
cond_func->functype() == Item_func::ISNULL_FUNC,
&tmp, 1, usable_tables);
}
break;
+ case Item_func::OPTIMIZE_EQUAL:
+ Item_equal *item_equal= (Item_equal *) cond;
+ Item *const_item= item_equal->get_const();
+ Item_equal_iterator it(*item_equal);
+ Item_field *item;
+ if (const_item)
+ {
+ /*
+ For each field field1 from item_equal consider the equality
+ field1=const_item as a condition allowing an index access of the table
+ with field1 by the keys value of field1.
+ */
+ while ((item= it++))
+ {
+ add_key_field(key_fields, *and_level, item->field,
+ TRUE, &const_item, 1, usable_tables);
+ }
+ }
+ else
+ {
+ /*
+ Consider all pairs of different fields included into item_equal.
+ For each of them (field1, field1) consider the equality
+ field1=field2 as a condition allowing an index access of the table
+ with field1 by the keys value of field2.
+ */
+ Item_equal_iterator fi(*item_equal);
+ while ((item= fi++))
+ {
+ Field *field= item->field;
+ while ((item= it++))
+ {
+ if (!field->eq(item->field))
+ {
+ add_key_field(key_fields, *and_level, field,
+ TRUE, (Item **) &item, 1, usable_tables);
+ }
+ }
+ it.rewind();
+ }
+ }
+ break;
}
- return;
}
/*
@@ -2669,21 +2815,33 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
{
uint keypart=keyuse->keypart;
uint found_part_ref_or_null= KEY_OPTIMIZE_REF_OR_NULL;
+ bool usable= 0;
+ table_map best_part_found_ref= 0;
+ double best_prev_record_reads= DBL_MAX;
do
{
if (!(rest_tables & keyuse->used_tables) &&
!(found_ref_or_null & keyuse->optimize))
{
found_part|=keyuse->keypart_map;
- found_ref|= keyuse->used_tables;
+ double tmp= prev_record_reads(join,
+ (table_map) (found_ref | keyuse->used_tables));
+ if (tmp < best_prev_record_reads)
+ {
+ best_part_found_ref= keyuse->used_tables;
+ best_prev_record_reads= tmp;
+ }
if (rec > keyuse->ref_table_rows)
rec= keyuse->ref_table_rows;
found_part_ref_or_null&= keyuse->optimize;
+ usable= 1;
}
keyuse++;
- found_ref_or_null|= found_part_ref_or_null;
+ found_ref|= best_part_found_ref;
} while (keyuse->table == table && keyuse->key == key &&
keyuse->keypart == keypart);
+ if (usable)
+ found_ref_or_null|= found_part_ref_or_null;
} while (keyuse->table == table && keyuse->key == key);
/*
@@ -3394,7 +3552,7 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
}
COND *tmp=make_cond_for_table(cond,used_tables,current_map);
- if (!tmp && tab->quick)
+ if (!tmp && tab->quick && tab->type == JT_ALL)
{ // Outer join
/*
Hack to handle the case where we only refer to a table
@@ -4089,6 +4247,583 @@ template class List<Item_func_match>;
template class List_iterator<Item_func_match>;
#endif
+/*
+ Eliminate nesting in AND/OR subexpressions od a condition
+
+ SYNOPSIS
+ flatten_condition()
+ cond condition where to eliminate nesting
+
+ DESCRIPTION
+ The function traverse the condition and recursively eliminates
+ nesting for AND/OR subexpressions:
+ ... AND (p AND ... r) AND ... => ... AND p AND ... r AND ...
+ ... OR (p OR ... r) OR ... => ... OR p OR ... r OR ...
+
+ NOTES
+ Nesting in AND/OR subexpresions inside of NOT/XOR formulas is not
+ eliminated.
+
+ RETURN
+ The transformed condition
+*/
+static Item *flatten_condition(COND *cond)
+{
+ if (cond->type() == Item::COND_ITEM)
+ {
+ Item_func::Functype functype= ((Item_cond*) cond)->functype();
+ if (functype == Item_func::COND_AND_FUNC ||
+ functype == Item_func::COND_OR_FUNC)
+ {
+
+ List<Item> *args= ((Item_cond*) cond)->argument_list();
+ List_iterator<Item> li(*args);
+ Item *item;
+ List<Item> list;
+ while ((item= li++))
+ {
+ item= flatten_condition(item);
+ if (item->type() == Item::COND_ITEM &&
+ ((Item_func*) item)->functype() == functype)
+ {
+ list.concat(((Item_cond*) item)->argument_list());
+ li.remove();
+ }
+ }
+ args->concat(&list);
+ }
+ }
+ return cond;
+}
+
+
+/*
+ Find the multiple equality predicate containing a field
+
+ SYNOPSIS
+ find_item_equal()
+ cond_equal multiple equalities to search in
+ field field to look for
+ inherited_fl :out set up to TRUE iff multiple equality is found
+ on upper levels (not on current level of cond_equal)
+
+ DESCRIPTION
+ The function retrieves the multiple equalities accessed through
+ the con_equal structure from current level and up looking for
+ an equality containing field. It stops retrieval as soon as the equality
+ is found and set up inherited_fl to TRUE if it's found on upper levels.
+
+ RETURN
+ Item_equal for the found multiple equality predicate if a success;
+ NULL - otherwise.
+*/
+
+Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
+ bool *inherited_fl)
+{
+ Item_equal *item= 0;
+ bool in_upper_level= FALSE;
+ while (cond_equal)
+ {
+ List_iterator_fast<Item_equal> li(cond_equal->current_level);
+ while ((item= li++))
+ {
+ if (item->contains(field))
+ goto finish;
+ }
+ in_upper_level= TRUE;
+ cond_equal= cond_equal->parent_level;
+ }
+ in_upper_level= FALSE;
+finish:
+ if (inherited_fl)
+ *inherited_fl= in_upper_level;
+ return item;
+}
+
+/*
+ Check whether an item is a simple equality predicate and if so
+ create/find a multiple equality for this predicate
+
+ SYNOPSIS
+ check_equality()
+ item item to check
+ cond_equal multiple equalities that must hold together with the predicate
+
+ DESCRIPTION
+ This function first checks whether an item is a simple equality i.e.
+ the one that equates a field with another field or a constant.
+ If this is the case the function looks a for a multiple equality
+ in the lists referenced directly or indirectly by cond_equal. If it
+ doesn't find any it builds a multiple equality that covers
+ the predicate, i.e. the predicate can be inferred from it. The built
+ multiple equality could be obtained in such a way: create a binary
+ multiple equality equivalent to the predicate, than merge it, if
+ possible, with one of old multiple equalities. This guarantees that
+ the set of multiple equalities covering equality predicates will
+ be minimal.
+
+ NOTES
+ Now only fields that have the same type defintions (verified by
+ the Field::eq_def method) are placed to the same multiple equalities.
+ Because of this some equality predicates are not eliminated and
+ can be used in constant propagation procedure.
+ We could weeken the equlity test as soon as at least one of the
+ equal fields is to be equal to a constant. It would require a
+ more complicated implementation: we would have to store, in
+ general case, its own constant for each fields from the multiple
+ equality. But at the same time it would allow us to get rid
+ of constant propagation completely: it would be done by the call
+ to build_all_equal_items.
+
+ IMPLEMENTATION
+ The implementation does not follow exactly the above rules to
+ build a new multiple equality for the equality predicate.
+ If it processes the equality of the form field1=field2, it
+ looks for multiple equalities me1 containig field1 and me2 containing
+ field2. If only one of them is found the fuction expand it by
+ the lacking field. If multiple equalities for both fields are
+ found they are merged. If both searches fail a new multiple equality
+ containing just field1 and field2 is added to the existing
+ multiple equalities.
+ If the function processes the predicate of the form field1=const,
+ it looks for a multiple equality containing field1. If found, the
+ function checks the constant of the multiple equality. If the value
+ is unknown, it is setup to const. Otherwise the value is compared with
+ const and the evaluation of the equality predicate is performed.
+ When expanding/merging equality predicates from the upper levels
+ the function first copies them for the current level. It looks
+ acceptable, as this happens rarely. The implementation without
+ copying would be much more complicated.
+
+ RETURN
+ TRUE - if the predicate is a simple equality predicate
+ FALSE - otherwise
+*/
+
+static bool check_equality(Item *item, COND_EQUAL *cond_equal)
+{
+ if (item->type() == Item::FUNC_ITEM &&
+ ((Item_func*) item)->functype() == Item_func::EQ_FUNC)
+ {
+ Item *left_item= ((Item_func*) item)->arguments()[0];
+ Item *right_item= ((Item_func*) item)->arguments()[1];
+ if (left_item->type() == Item::FIELD_ITEM &&
+ right_item->type() == Item::FIELD_ITEM)
+ {
+ /* The predicate the form field1=field2 is processed */
+
+ Field *left_field= ((Item_field*) left_item)->field;
+ Field *right_field= ((Item_field*) right_item)->field;
+
+ if (!left_field->eq_def(right_field))
+ return FALSE;
+
+ if (left_field->eq(right_field))
+ return TRUE;
+
+ /* Search for multiple equalities containing field1 and/or field2 */
+ bool left_copyfl, right_copyfl;
+ Item_equal *left_item_equal=
+ find_item_equal(cond_equal, left_field, &left_copyfl);
+ Item_equal *right_item_equal=
+ find_item_equal(cond_equal, right_field, &right_copyfl);
+
+ if (left_item_equal && left_item_equal == right_item_equal)
+ {
+ /*
+ The equality predicate is inference of one of the existing
+ multiple equalities
+ */
+ return TRUE;
+ }
+
+ /* Copy the found multiple equalities at the current level if needed */
+ if (left_copyfl)
+ {
+ left_item_equal= new Item_equal(left_item_equal);
+ cond_equal->current_level.push_back(left_item_equal);
+ }
+ if (right_copyfl)
+ {
+ right_item_equal= new Item_equal(right_item_equal);
+ cond_equal->current_level.push_back(right_item_equal);
+ }
+
+ if (left_item_equal)
+ {
+ if (! right_item_equal)
+ left_item_equal->add((Item_field *) right_item);
+ else
+ {
+ /* Merge two multiple equalities forming a new one */
+ left_item_equal->merge(right_item_equal);
+ /* Remove the merged multiple equality from the list */
+ List_iterator<Item_equal> li(cond_equal->current_level);
+ while ((li++) != right_item_equal);
+ li.remove();
+ }
+ }
+ else
+ {
+ if (right_item_equal)
+ right_item_equal->add((Item_field *) left_item);
+ else
+ {
+ /* Multiple equalities for neither of the fields has been found */
+ Item_equal *item= new Item_equal((Item_field *) left_item,
+ (Item_field *) right_item);
+ cond_equal->current_level.push_back(item);
+ }
+ }
+ return TRUE;
+ }
+ else
+ {
+ /* The predicate of the form field=const/const=field is processed */
+ Item *const_item= 0;
+ Item_field *field_item= 0;
+ if (left_item->type() == Item::FIELD_ITEM &&
+ right_item->const_item())
+ {
+ field_item= (Item_field*) left_item;
+ const_item= right_item;
+ }
+ else if (right_item->type() == Item::FIELD_ITEM &&
+ left_item->const_item())
+ {
+ field_item= (Item_field*) right_item;
+ const_item= left_item;
+ }
+ if (const_item &&
+ field_item->result_type() == const_item->result_type())
+ {
+ bool copyfl;
+ Item_equal *item_equal = find_item_equal(cond_equal,
+ field_item->field, ©fl);
+ if (copyfl)
+ {
+ item_equal= new Item_equal(item_equal);
+ cond_equal->current_level.push_back(item_equal);
+ }
+ if (item_equal)
+ {
+ /*
+ The flag cond_false will be set to 1 after this, if item_equal
+ already contains a constant and its value is not equal to
+ the value of const_item.
+ */
+ item_equal->add(const_item);
+ }
+ else
+ {
+ item_equal= new Item_equal(const_item, field_item);
+ cond_equal->current_level.push_back(item_equal);
+ }
+ return TRUE;
+ }
+ }
+ }
+ return FALSE;
+}
+
+/*
+ Replace all equality predicates in a condition by multiple equality items
+
+ SYNOPSIS
+ build_all_equal_items()
+ cond condition(expression) where to make replacement
+ inherited path to all inherited multiple equality items
+
+ DESCRIPTION
+ At each 'and' level the function detects items for equality predicates
+ and replaced them by a set of multiple equality items of class Item_equal,
+ taking into account inherited equalities from upper levels.
+ If an equality predicate is used not in a conjunction it's just
+ replaced by a multiple equality predicate.
+ The functuion also traverse the cond tree and and for each field reference
+ sets a ponter to the multiple equality item containing the field, if there
+ is any. If this multiple equality equates fields to a constant the
+ function replace the field reference by the constant.
+
+ NOTES
+ Multiple equality predicate =(f1,..fn) is equivalent to the conjuction of
+ f1=f2, .., fn-1=fn. It substitutes any inference from these
+ equality predicates that is equivalent to the conjunction.
+ Thus, =(a1,a2,a3) can substitute for ((a1=a3) AND (a2=a3) AND (a2=a1)) as
+ it is equivalent to ((a1=a2) AND (a2=a3)).
+ The function always makes a subsitution of all equality predicates occured
+ in a conjuction for a minimal set of multiple equality predicates.
+ This set can be considered as a canonical representation of the
+ sub-conjunction of the equality predicates.
+ E.g. (t1.a=t2.b AND t2.b>5 AND t1.a=t3.c) is replaced by
+ (=(t1.a,t2.b,t3.c) AND t2.b>5), not by
+ (=(t1.a,t2.b) AND =(t1.a,t3.c) AND t2.b>5);
+ while (t1.a=t2.b AND t2.b>5 AND t3.c,t4.d) is replaced by
+ (=(t1.a,t2.b) AND =(t3.c=t4.d) AND t2.b>5),
+ but if additionally =(t4.d,t2.b) is inherited, it
+ will be replaced by (=(t1.a,t2.b,t3.c,t4.d) AND t2.b>5)
+
+ IMPLEMENTATION
+ The function performs the substitution in a recursive descent by
+ the condtion tree, passing to the next AND level a chain of multiple
+ equality predicates which have been built at the upper levels.
+ The Item_equal items built at the level are attached to other
+ non-equality conjucts as a sublist. The pointer to the inherited
+ multiple equalities is saved in the and condition object (Item_cond_and).
+ This chain allows us for any field reference occurence easyly to find a
+ multiple equality that must be held for this occurence.
+
+ RETURN
+ pointer to the transformed condition
+*/
+
+static COND *build_all_equal_items(COND *cond,
+ COND_EQUAL *inherited)
+{
+ COND_EQUAL cond_equal;
+ cond_equal.parent_level= inherited;
+
+ if (cond->type() == Item::COND_ITEM)
+ {
+ bool and_level= ((Item_cond*) cond)->functype() ==
+ Item_func::COND_AND_FUNC;
+ List<Item> *args= ((Item_cond*) cond)->argument_list();
+
+ List_iterator<Item> li(*args);
+ Item *item;
+
+ if (and_level)
+ {
+ /*
+ Retrieve all conjucts of this level detecting the equality
+ that are subject to substitution by multiple equality items and
+ removing each such predicate from the conjunction after after having
+ found/created a multiple equality whose inference the predicate is.
+ */
+ while ((item= li++))
+ {
+ if (check_equality(item, &cond_equal))
+ li.remove();
+ }
+
+ List_iterator_fast<Item_equal> it(cond_equal.current_level);
+ while ((item= it++))
+ {
+ item->fix_fields(current_thd, 0, 0);
+ }
+ ((Item_cond_and*)cond)->cond_equal= cond_equal;
+ inherited= &(((Item_cond_and*)cond)->cond_equal);
+ }
+ /*
+ Make replacement of equality predicates for lower levels
+ of the condition expression.
+ */
+ List_iterator<Item> it(*args);
+ while((item= it++))
+ {
+ Item *new_item;
+ if ((new_item = build_all_equal_items(item, inherited))!= item)
+ {
+ /* This replacement happens only for standalone equalities */
+ it.replace(new_item);
+ }
+ }
+ if (and_level)
+ args->concat((List<Item> *)&cond_equal.current_level);
+ }
+ else if (cond->type() == Item::FUNC_ITEM)
+ {
+ /* Standalone equalities are handled here */
+ Item_equal *item_equal;
+ if (check_equality(cond, &cond_equal) &&
+ (item_equal= cond_equal.current_level.pop()))
+ {
+ item_equal->fix_fields(current_thd, 0, 0);
+ return item_equal;
+ }
+ else
+ {
+ cond= cond->traverse(&Item::equal_fields_propagator,
+ (byte *) inherited);
+ cond->update_used_tables();
+ }
+ }
+ return cond;
+}
+
+
+/*
+ Generate minimal set of simple equalities equivalent to a multiple equality
+
+ SYNOPSIS
+ eliminate_item_equal()
+ cond condition to add the generated equality to
+ cond_equal structure to access multiple equality of upper levels
+ item_equal multiple equality to generate simple equality from
+
+ DESCRIPTION
+ The function retrieves the fields of the multiple equality item
+ item_equal and for each field f:
+ - if item_equal contains const it generates the equality f=const_item;
+ - otherwise, if f is not the first field, generates the equality
+ f=item_equal->get_first().
+ All generated equality are added to the cond conjunction.
+
+ NOTES
+ Before generating an equality function checks that it has not
+ been generated for multiple equalies of the upper levels.
+ If cond is equal to 0, then not more then one equality is generated
+ and a pointer to it is returned as the result of the function.
+
+ RETURN
+ The condition with generated simple equalities or
+ a pointer to the simple generated equality.
+*/
+
+static Item *eliminate_item_equal(COND *cond, COND_EQUAL *cond_equal,
+ Item_equal *item_equal)
+{
+ Item *item_const= item_equal->get_const();
+ Item_equal_iterator it(*item_equal);
+ Item *head;
+ if (item_const)
+ head= item_const;
+ else
+ {
+ head= item_equal->get_first();
+ it++;
+ }
+ Item_field *item_field;
+ Item *new_item= 0;
+ while ((item_field= it++))
+ {
+ Item_equal *upper= item_field->find_item_equal(cond_equal);
+ Item_field *item= item_field;
+ if (upper)
+ {
+ if (item_const)
+ {
+ if (upper->get_const())
+ item= 0;
+ }
+ else
+ {
+ Item_equal_iterator li(*item_equal);
+ while ((item= li++) != item_field)
+ {
+ if (item->find_item_equal(cond_equal) == upper)
+ break;
+ }
+ }
+ }
+ if (item == item_field)
+ {
+ if (!cond && new_item)
+ {
+ cond= new Item_cond_and();
+ ((Item_cond *) cond)->add(new_item);
+ }
+ item_field->item_equal= item_equal;
+ new_item= new Item_func_eq(item_field, head);
+ ((Item_func_eq *) new_item)->fix_length_and_dec();
+ if (cond)
+ ((Item_cond *) cond)->add(new_item);
+ }
+ }
+ if (!cond)
+ cond= (COND *) new_item;
+ return cond;
+}
+
+
+/*
+ Substitute every field reference in a condition by the best equal field
+ and eliminate all multiplle equality predicates
+
+ SYNOPSIS
+ substitute_for_best_equal_field()
+ cond condition to process
+ table_join_idx index to tables determining field preference
+
+ DESCRIPTION
+ The function retrieves the cond condition and for each encountered
+ multiple equality predicate it sorts the field references in it
+ according to the order of tables specified by the table_join_idx
+ parameter. Then it eliminates the multiple equality predicate it
+ replacing it by the conjunction of simple equality predicates
+ equating every field from the multiple equality to the first
+ field in it, or to the constant, if there is any.
+ After this the function retrieves all other conjuncted
+ predicates substitute every field reference by the field reference
+ to the first equal field or equal constant if there are any.
+
+ NOTES
+ At the first glance full sort of fields in multiple equality
+ seems to be an overkill. Yet it's not the case due to possible
+ new fields in multiple equality item of lower levels. We want
+ the order in them to comply with the order of upper levels.
+
+ RETURN
+ The transformed condition
+*/
+
+static COND* substitute_for_best_equal_field(COND *cond,
+ void *table_join_idx)
+{
+ Item_equal *item_equal;
+
+ if (cond->type() == Item::COND_ITEM)
+ {
+ List<Item> *cond_list= ((Item_cond*) cond)->argument_list();
+ COND_EQUAL *cond_equal= 0;
+
+ bool and_level= ((Item_cond*) cond)->functype() ==
+ Item_func::COND_AND_FUNC;
+ if (and_level)
+ {
+ cond_equal= &((Item_cond_and *) cond)->cond_equal;
+ cond_list->disjoin((List<Item> *) &cond_equal->current_level);
+
+ List_iterator_fast<Item_equal> it(cond_equal->current_level);
+ while((item_equal= it++))
+ {
+ item_equal->sort(table_join_idx);
+ }
+ }
+
+ List_iterator<Item> li(*cond_list);
+ Item *item;
+ while ((item= li++))
+ {
+ Item *new_item =substitute_for_best_equal_field(item,
+ table_join_idx);
+ if (new_item != item)
+ li.replace(new_item);
+ }
+
+ if (and_level)
+ {
+ List_iterator_fast<Item_equal> it(cond_equal->current_level);
+ while((item_equal= it++))
+ {
+ eliminate_item_equal(cond, cond_equal->parent_level, item_equal);
+ }
+ }
+ }
+ else if (cond->type() == Item::FUNC_ITEM &&
+ ((Item_cond*) cond)->functype() == Item_func::MULT_EQUAL_FUNC)
+ {
+ item_equal= (Item_equal *) cond;
+ item_equal->sort(table_join_idx);
+ return eliminate_item_equal(0, 0, item_equal);
+ }
+ else
+ cond->walk(&Item::replace_equal_field_processor, 0);
+ return cond;
+}
+
+
/*
change field = field to field = const for each found field = const in the
and_level
@@ -4318,9 +5053,6 @@ optimize_cond(COND *conds,Item::cond_result *cond_value)
return conds;
}
DBUG_EXECUTE("where",print_where(conds,"original"););
- /* eliminate NOT operators */
- conds= eliminate_not_funcs(conds);
- DBUG_EXECUTE("where", print_where(conds, "after negation elimination"););
/* change field = field to field = const for each found field = const */
propagate_cond_constants((I_List<COND_CMP> *) 0,conds,conds);
/*
@@ -4412,7 +5144,8 @@ remove_eq_conds(COND *cond,Item::cond_result *cond_value)
}
}
else if (cond->type() == Item::FUNC_ITEM &&
- ((Item_func*) cond)->functype() == Item_func::ISNULL_FUNC)
+ ((Item_func*) cond)->functype() == Item_func::ISNULL_FUNC &&
+ !cond->const_item())
{
/*
Handles this special case for some ODBC applications:
@@ -4463,6 +5196,22 @@ remove_eq_conds(COND *cond,Item::cond_result *cond_value)
}
}
}
+ else if (cond->type() == Item::FUNC_ITEM &&
+ ((Item_func*) cond)->functype() == Item_func::MULT_EQUAL_FUNC)
+ {
+ /*
+ The is_false method for an multiple equality item returns 1
+ when the conjunction with this item originally contained an
+ equality that was inconsistent with the multiple equality
+ predicate or has been inherited from other multiple equality
+ for which is_false returns 1.
+ */
+ if (((Item_equal *) cond)->is_false())
+ {
+ *cond_value= Item::COND_FALSE;
+ return (COND*) 0;
+ }
+ }
else if (cond->const_item())
{
*cond_value= eval_const_cond(cond) ? Item::COND_TRUE : Item::COND_FALSE;
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 24854713a0e..ad2adc2ee0f 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -184,6 +184,7 @@ class JOIN :public Sql_alloc
ORDER *order, *group_list, *proc_param; //hold parameters of mysql_select
COND *conds; // ---"---
Item *conds_history; // store WHERE for explain
+ COND_EQUAL *cond_equal;
TABLE_LIST *tables_list; //hold 'tables' parameter of mysql_selec
SQL_SELECT *select; //created in optimisation phase
Item **ref_pointer_array; //used pointer reference for this select
@@ -243,6 +244,7 @@ class JOIN :public Sql_alloc
ref_pointer_array_size= 0;
zero_result_cause= 0;
optimized= 0;
+ cond_equal= 0;
fields_list= fields;
bzero((char*) &keyuse,sizeof(keyuse));
--
2.30.9