table.h, sql_select.h:

  Added the code processing on expressions for applying
  multiple equalities.
sql_select.cc:
  Post-merge fixes for Item_equal patch.
  Added the code processing on expressions for applying
  multiple equalities.
Many files:
  Post-merge fixes for Item_equal patch.
item_cmpfunc.cc:
  Post-merge fixes for Item_equal patch.
  Fixed a problem when an equality field=const cannot be applied to
  the predicate P(field,c) for constant propagation as a conversion
  of field is needed.
item.h, item.cc:
  Fixed a problem when an equality field=const cannot be applied to
  the predicate P(field,c) for constant propagation as a conversion
  of field is needed.

mysql-test/r/func_test.result

@@ -79,7 +79,7 @@ explain extended select * from t1 where 1 xor 1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (1 xor 1)
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1`
 select - a from t1;
 - a
 -1

mysql-test/r/index_merge.result

@@ -82,7 +82,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t0	index_merge	i2,i3,i4	i2,i3	4,4	NULL	2	Using union(i2,i3); Using where
 explain select * from t0 where key2=10 or key3=3 or key4 is null;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t0	index_merge	i2,i3	i2,i3	4,4	NULL	2	Using where
+1	SIMPLE	t0	index_merge	i2,i3	i2,i3	4,4	NULL	2	Using union(i2,i3); Using where
 explain select key1 from t0 where (key1 <=> null) or (key2 < 5) or 
 (key3=10) or (key4 <=> null);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
@@ -257,8 +257,8 @@ explain
 select * from t0,t1 where (t0.key1=t1.key1) and 
 (t0.key1=3 or t0.key2=4) and t1.key1<200;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t0	index_merge	i1,i2	i1,i2	4,4	NULL	2	Using union(i1,i2); Using where
-1	SIMPLE	t1	ref	i1	i1	4	test.t0.key1	1	Using where
+1	SIMPLE	t0	range	i1,i2	i1	4	NULL	179	Using where
+1	SIMPLE	t1	ref	i1	i1	4	test.t0.key1	1	
 explain 
 select * from t0,t1 where (t0.key1=t1.key1) and 
 (t0.key1=3 or t0.key2<4) and t1.key1=2;

mysql-test/r/range.result

@@ -254,12 +254,12 @@ INSERT INTO t2 VALUES (0),(0),(1),(1),(2),(2);
 explain select * from t1, t2 where (t1.key1 <t2.keya + 1) and t2.keya=3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index
-1	SIMPLE	t1	ALL	i1	NULL	NULL	NULL	4	Range checked for each record (index map: 0x1)
+1	SIMPLE	t1	index	i1	i1	4	NULL	4	Using where; Using index
 explain select * from t1 force index(i1), t2 force index(j1) where 
 (t1.key1 <t2.keya + 1) and t2.keya=3;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ref	j1	j1	4	const	1	Using index
-1	SIMPLE	t1	ALL	i1	NULL	NULL	NULL	4	Range checked for each record (index map: 0x1)
+1	SIMPLE	t1	index	i1	i1	4	NULL	4	Using where; Using index
 DROP TABLE t1,t2;
 CREATE TABLE t1 (
 a int(11) default NULL,

mysql-test/r/subselect.result

@@ -331,7 +331,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.clinic_uq	1	Using index
 Warnings:
 Note	1276	Field or reference 'clinic_uq' of SELECT #2 was resolved in SELECT #1
-Note	1003	select `test`.`t6`.`patient_uq` AS `patient_uq`,`test`.`t6`.`clinic_uq` AS `clinic_uq` from `test`.`t6` where exists(select 1 AS `Not_used` from `test`.`t7` where (`test`.`t7`.`uq` = `test`.`t6`.`clinic_uq`))
+Note	1003	select `test`.`t6`.`patient_uq` AS `patient_uq`,`test`.`t6`.`clinic_uq` AS `clinic_uq` from `test`.`t6` where exists(select 1 AS `Not_used` from `test`.`t7` where (`test`.`t6`.`clinic_uq` = `test`.`t7`.`uq`))
 select * from t1 where a= (select a from t2,t4 where t2.b=t4.b);
 ERROR 23000: Column 'a' in field list is ambiguous
 drop table t1,t2,t3;
@@ -545,7 +545,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	const	PRIMARY,numreponse	PRIMARY	7	const,const	1	Using index
 2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
 Warnings:
-Note	1003	select `test`.`t1`.`numreponse` AS `numreponse` from `test`.`t1` where ((`test`.`t1`.`numeropost` = _latin1'1') and (`test`.`t1`.`numreponse` = 3))
+Note	1003	select `test`.`t1`.`numreponse` AS `numreponse` from `test`.`t1` where ((`test`.`t1`.`numreponse` = (select max(`test`.`t1`.`numreponse`) AS `MAX(numreponse)` from `test`.`t1` where (`test`.`t1`.`numeropost` = _latin1'1'))) and (`test`.`t1`.`numeropost` = _latin1'1'))
 drop table t1;
 CREATE TABLE t1 (a int(1));
 INSERT INTO t1 VALUES (1);
@@ -1313,7 +1313,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	func	1	Using where
 2	DEPENDENT SUBQUERY	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.b	1	Using where; Using index
 Warnings:
-Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t1`.`b` = `test`.`t3`.`a`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
+Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t1`.`b`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
 drop table t1, t2, t3;
 create table t1 (a int, b int, index a (a,b));
 create table t2 (a int, index a (a));
@@ -1675,10 +1675,10 @@ Note	1003	select `test`.`t1`.`id` AS `id`,`test`.`t1`.`text` AS `text` from `tes
 explain extended select * from t1 as tt where not exists (select id from t1 where id < 8 and (id = tt.id or id is null) having id is not null);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	tt	ALL	NULL	NULL	NULL	NULL	12	Using where
-2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	test.tt.id	7	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	eq_ref	PRIMARY	PRIMARY	4	test.tt.id	1	Using where; Using index
 Warnings:
 Note	1276	Field or reference 'tt.id' of SELECT #2 was resolved in SELECT #1
-Note	1003	select `test`.`tt`.`id` AS `id`,`test`.`tt`.`text` AS `text` from `test`.`t1` `tt` where not(exists(select `test`.`t1`.`id` AS `id` from `test`.`t1` where ((`test`.`t1`.`id` < 8) and ((`test`.`t1`.`id` = `test`.`tt`.`id`) or isnull(`test`.`t1`.`id`))) having (`test`.`t1`.`id` is not null)))
+Note	1003	select `test`.`tt`.`id` AS `id`,`test`.`tt`.`text` AS `text` from `test`.`t1` `tt` where not(exists(select `test`.`t1`.`id` AS `id` from `test`.`t1` where ((`test`.`t1`.`id` < 8) and (`test`.`tt`.`id` = `test`.`t1`.`id`)) having (`test`.`t1`.`id` is not null)))
 insert into t1 (id, text) values (1000, 'text1000'), (1001, 'text1001');
 create table t2 (id int not null, text varchar(20) not null default '', primary key (id));
 insert into t2 (id, text) values (1, 'text1'), (2, 'text2'), (3, 'text3'), (4, 'text4'), (5, 'text5'), (6, 'text6'), (7, 'text7'), (8, 'text8'), (9, 'text9'), (10, 'text10'), (11, 'text1'), (12, 'text2'), (13, 'text3'), (14, 'text4'), (15, 'text5'), (16, 'text6'), (17, 'text7'), (18, 'text8'), (19, 'text9'), (20, 'text10'),(21, 'text1'), (22, 'text2'), (23, 'text3'), (24, 'text4'), (25, 'text5'), (26, 'text6'), (27, 'text7'), (28, 'text8'), (29, 'text9'), (30, 'text10'), (31, 'text1'), (32, 'text2'), (33, 'text3'), (34, 'text4'), (35, 'text5'), (36, 'text6'), (37, 'text7'), (38, 'text8'), (39, 'text9'), (40, 'text10'), (41, 'text1'), (42, 'text2'), (43, 'text3'), (44, 'text4'), (45, 'text5'), (46, 'text6'), (47, 'text7'), (48, 'text8'), (49, 'text9'), (50, 'text10');
@@ -1704,7 +1704,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	b	eq_ref	PRIMARY	PRIMARY	4	test.a.id	2	
 1	SIMPLE	c	eq_ref	PRIMARY	PRIMARY	4	func	1	Using where
 Warnings:
-Note	1003	select `test`.`a`.`id` AS `id`,`test`.`a`.`text` AS `text`,`test`.`b`.`id` AS `id`,`test`.`b`.`text` AS `text`,`test`.`c`.`id` AS `id`,`test`.`c`.`text` AS `text` from `test`.`t1` `a` left join `test`.`t2` `b` on(((`test`.`a`.`id` = `test`.`b`.`id`) or isnull(`test`.`b`.`id`))) join `test`.`t1` `c` where (if(isnull(`test`.`b`.`id`),1000,`test`.`b`.`id`) = `test`.`c`.`id`)
+Note	1003	select `test`.`a`.`id` AS `id`,`test`.`a`.`text` AS `text`,`test`.`b`.`id` AS `id`,`test`.`b`.`text` AS `text`,`test`.`c`.`id` AS `id`,`test`.`c`.`text` AS `text` from `test`.`t1` `a` left join `test`.`t2` `b` on(((`test`.`b`.`id` = `test`.`a`.`id`) or isnull(`test`.`b`.`id`))) join `test`.`t1` `c` where (if(isnull(`test`.`b`.`id`),1000,`test`.`b`.`id`) = `test`.`c`.`id`)
 drop table t1,t2;
 create table t1 (a int);
 insert into t1 values (1);
@@ -1832,7 +1832,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 2	DEPENDENT SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
 Warnings:
 Note	1276	Field or reference 'up.a' of SELECT #2 was resolved in SELECT #1
-Note	1003	select `test`.`up`.`a` AS `a`,`test`.`up`.`b` AS `b` from `test`.`t1` `up` where exists(select 1 AS `Not_used` from `test`.`t1` where (`test`.`t1`.`a` = `test`.`up`.`a`))
+Note	1003	select `test`.`up`.`a` AS `a`,`test`.`up`.`b` AS `b` from `test`.`t1` `up` where exists(select 1 AS `Not_used` from `test`.`t1` where (`test`.`up`.`a` = `test`.`t1`.`a`))
 drop table t1;
 CREATE TABLE t1 (t1_a int);
 INSERT INTO t1 VALUES (1);

sql/item.cc

@@ -408,7 +408,7 @@ bool DTCollation::aggregate(DTCollation &dt, bool superset_conversion)
 
 Item_field::Item_field(Field *f)
   :Item_ident(NullS, f->table_name, f->field_name),
-   item_equal(0),
+  item_equal(0), no_const_subst(0),
    have_privileges(0), any_privileges(0)
 {
   set_field(f);
@@ -419,7 +419,7 @@ Item_field::Item_field(Field *f)
 Item_field::Item_field(THD *thd, Field *f)
   :Item_ident(NullS, thd->strdup(f->table_name), 
               thd->strdup(f->field_name)),
-   item_equal(0),
+   item_equal(0), no_const_subst(0),
    have_privileges(0), any_privileges(0)
 {
   set_field(f);
@@ -432,11 +432,12 @@ Item_field::Item_field(THD *thd, Item_field *item)
   :Item_ident(thd, item),
    field(item->field),
    result_field(item->result_field),
+   item_equal(item->item_equal),
+   no_const_subst(item->no_const_subst),
    have_privileges(item->have_privileges),
    any_privileges(item->any_privileges)
 {
   collation.set(DERIVATION_IMPLICIT);
-  item_equal= item->item_equal;
 }
 
 void Item_field::set_field(Field *field_par)
@@ -1607,7 +1608,101 @@ void Item_field::cleanup()
     First Item_equal containing the field, if success
     0, otherwise
 */
+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;
+    }
+    /* 
+      The field is not found in any of the multiple equalities
+      of the current level. Look for it in upper levels
+    */
+    cond_equal= cond_equal->upper_levels;
+  }
+  return 0;
+}
+
+
+/*
+  Set a pointer to the multiple equality the field reference belongs to (if any)
+   
+  SYNOPSIS
+    equal_fields_propagator()
+    arg - reference to list of multiple equalities where
+          the field (this object) is to be looked for
+  
+  DESCRIPTION
+    The function looks for a multiple equality containing the field item
+    among those referenced by arg.
+    In the case such equality exists the function does the following.
+    If the found multiple equality contains a constant, then the field
+    reference is substituted for this constant, otherwise it sets a pointer
+    to the multiple equality in the field item.
+
+  NOTES
+    This function is supposed to be called as a callback parameter in calls
+    of the transform method.  
+
+  RETURN VALUES
+    pointer to the replacing constant item, if the field item was substituted 
+    pointer to the field item, otherwise.
+*/
 
+Item *Item_field::equal_fields_propagator(byte *arg)
+{
+  if (no_const_subst)
+    return this;
+  item_equal= find_item_equal((COND_EQUAL *) arg);
+  Item *item= 0;
+  if (item_equal)
+    item= item_equal->get_const();
+  if (!item)
+    item= this;
+  return item;
+}
+
+
+/*
+  Set a pointer to the multiple equality the field reference belongs to (if any)
+   
+  SYNOPSIS
+    replace_equal_field_processor()
+    arg - a dummy parameter, is not used here
+  
+  DESCRIPTION
+    The function replaces a pointer to a field in the Item_field object
+    by a pointer to another field.
+    The replacement field is taken from the very beginning of
+    the item_equal list which the Item_field object refers to (belongs to)  
+    If the Item_field object does not refer any Item_equal object,
+    nothing is done.
+
+  NOTES
+    This function is supposed to be called as a callback parameter in calls
+    of the walk method.  
+
+  RETURN VALUES
+    0 
+*/
+
+bool Item_field::replace_equal_field_processor(byte *arg)
+{
+  if (item_equal)
+  {
+    Item_field *subst= item_equal->get_first();
+    if (!field->eq(subst->field))
+    {
+      field= subst->field;
+      return 0;
+    }
+  }
+  return 0;
 }
 
 void Item::init_make_field(Send_field *tmp_field,

sql/item.h

@@ -457,6 +457,8 @@ protected:
   void set_field(Field *field);
 public:
   Field *field,*result_field;
+  Item_equal *item_equal;
+  bool no_const_subst;
   /*
     if any_privileges set to TRUE then here real effective privileges will
     be stored
@@ -468,7 +470,7 @@ public:
   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_equal(0),}
+    field(0), result_field(0), item_equal(0), no_const_subst(0),
      have_privileges(0), any_privileges(0)
   { collation.set(DERIVATION_IMPLICIT); }
   // Constructor need to process subselect with temporary tables (see Item)

sql/item_cmpfunc.cc

@@ -231,6 +231,8 @@ void Item_bool_func2::fix_length_and_dec()
         conv->collation.set(args[weak]->collation.derivation);
         conv->fix_fields(thd, 0, &conv);
       }
+      if (args[weak]->type() == FIELD_ITEM)
+        ((Item_field *)args[weak])->no_const_subst= 1;
       args[weak]= conv ? conv : args[weak];
     }
   }
@@ -1956,7 +1958,7 @@ Item_cond::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   char buff[sizeof(char*)];			// Max local vars in function
 #endif
   not_null_tables_cache= used_tables_cache= 0;
-  const_item_cache= 0;
+  const_item_cache= 1;
   /*
     and_table_cache is the value that Item_cond_or() returns for
     not_null_tables()
@@ -2051,7 +2053,7 @@ void Item_cond::split_sum_func(Item **ref_pointer_array, List<Item> &fields)
   List_iterator<Item> li(list);
   Item *item;
   used_tables_cache=0;
-  const_item_cache=0;
+  const_item_cache=1;
   while ((item=li++))
   {
     if (item->with_sum_func && item->type() != SUM_FUNC_ITEM)
@@ -2934,6 +2936,7 @@ void Item_equal::add(Item *c)
   }
   Item_func_eq *func= new Item_func_eq(c, const_item);
   func->set_cmp_func();
+  func->quick_fix_field();
   cond_false =  !(func->val_int());
 }
 

sql/opt_range.cc

@@ -3338,6 +3338,63 @@ static SEL_TREE *get_mm_tree(PARAM *param,COND *cond)
       }
     }
     
+    DBUG_RETURN(ftree);
+  }
+  default:
+    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);
+  }
+
+  /* 
+     If the where condition contains a predicate (ti.field op const),
+     then not only SELL_TREE for this predicate is built, but
+     the trees for the results of substitution of ti.field for
+     each tj.field belonging to the same multiple equality as ti.field
+     are built as well.
+     E.g. for WHERE t1.a=t2.a AND t2.a > 10 
+     a SEL_TREE for t2.a > 10 will be built for quick select from t2
+     and   
+     a SEL_TREE for t1.a > 10 will be built for quick select from t1.
+  */
+     
+  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);
 }
 

sql/sql_select.h

@@ -91,7 +91,8 @@ typedef struct st_join_table {
   SQL_SELECT	*select;
   COND		*select_cond;
   QUICK_SELECT_I *quick;
-  Item		*on_expr;       /* associated on expression                  */
+  Item	       **on_expr_ref;   /* pointer to the associated on expression   */
+  COND_EQUAL    *cond_equal;    /* multiple equalities for the on expression */
   st_join_table *first_inner;   /* first inner table for including outerjoin */
   bool           found;         /* true after all matches or null complement */
   bool           not_null_compl;/* true before null complement is added      */

sql/table.h

@@ -21,6 +21,7 @@ class Item;				/* Needed by ORDER */
 class GRANT_TABLE;
 class st_select_lex_unit;
 class st_select_lex;
+class COND_EQUAL;
 
 /* Order clause list element */
 
@@ -209,6 +210,7 @@ typedef struct st_table_list
   char		*db, *alias, *real_name;
   char          *option;                /* Used by cache index  */
   Item		*on_expr;		/* Used with outer join */
+  COND_EQUAL    *cond_equal;            /* Used with outer join */
   struct st_table_list *natural_join;	/* natural join on this table*/
   /* ... join ... USE INDEX ... IGNORE INDEX */
   List<String>	*use_index, *ignore_index;