Merge rurik.mysql.com:/home/igor/mysql-5.0-opt

into  rurik.mysql.com:/home/igor/dev-opt/mysql-5.0-opt-bug16081

mysql-test/r/join_outer.result

@@ -1126,7 +1126,7 @@ a	b	a	b
 7	8	7	5
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a = t2.a OR t1.a = t2.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	Using where
+1	SIMPLE	t2	ALL	PRIMARY	NULL	NULL	NULL	4	
 1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.a	1	
 EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON t1.a = t2.a WHERE t1.a IN(t2.a, t2.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

mysql-test/r/row.result

@@ -181,3 +181,128 @@ SELECT ROW(1,1,1) = ROW(1,1,1) as `1`, ROW(1,1,1) = ROW(1,2,1) as `0`, ROW(1,NUL
 select row(NULL,1)=(2,0);
 row(NULL,1)=(2,0)
 0
+CREATE TABLE t1 (a int, b int, PRIMARY KEY (a,b));
+INSERT INTO t1 VALUES (1,1), (2,1), (3,1), (1,2), (3,2), (3,3);
+EXPLAIN SELECT * FROM t1 WHERE a=3 AND b=2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY	PRIMARY	8	const,const	1	Using index
+EXPLAIN SELECT * FROM t1 WHERE (a,b)=(3,2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	const	PRIMARY	PRIMARY	8	const,const	1	Using index
+SELECT * FROM t1 WHERE a=3 and b=2;
+a	b
+3	2
+SELECT * FROM t1 WHERE (a,b)=(3,2);
+a	b
+3	2
+CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a,b,c));
+INSERT INTO t2 VALUES
+(1,1,2), (3,1,3), (1,2,2), (4,4,2),
+(1,1,1), (3,1,1), (1,2,1);
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b=t2.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	8	test.t1.a,test.t1.b	1	Using index
+EXPLAIN SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	8	test.t1.a,test.t1.b	1	Using index
+SELECT * FROM t1,t2 WHERE t1.a=t2.a and t1.b=t2.b;
+a	b	a	b	c
+1	1	1	1	1
+1	1	1	1	2
+1	2	1	2	1
+1	2	1	2	2
+3	1	3	1	1
+3	1	3	1	3
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b);
+a	b	a	b	c
+1	1	1	1	1
+1	1	1	1	2
+1	2	1	2	1
+1	2	1	2	2
+3	1	3	1	1
+3	1	3	1	3
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b=2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	5	Using where; Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+EXPLAIN SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	5	Using where; Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+SELECT * FROM t1,t2 WHERE t1.a=1 and t1.b=t2.b;
+a	b	a	b	c
+1	1	1	1	2
+1	1	3	1	3
+1	2	1	2	2
+1	1	1	1	1
+1	1	3	1	1
+1	2	1	2	1
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,2);
+a	b	a	b	c
+1	2	1	1	1
+1	2	1	1	2
+1	2	1	2	1
+1	2	1	2	2
+3	2	3	1	1
+3	2	3	1	3
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b+1);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using where; Using index
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`a` = `test`.`t1`.`a`) and (`test`.`t1`.`b` = (`test`.`t2`.`b` + 1)))
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b+1);
+a	b	a	b	c
+1	2	1	1	1
+1	2	1	1	2
+3	2	3	1	1
+3	2	3	1	3
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t1.a-1,t1.b)=(t2.a-1,t2.b+1);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	index	NULL	PRIMARY	12	NULL	7	Using where; Using index
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t1` join `test`.`t2` where (((`test`.`t1`.`a` - 1) = (`test`.`t2`.`a` - 1)) and (`test`.`t1`.`b` = (`test`.`t2`.`b` + 1)))
+SELECT * FROM t1,t2 WHERE (t1.a-1,t1.b)=(t2.a-1,t2.b+1);
+a	b	a	b	c
+1	2	1	1	2
+3	2	3	1	3
+1	2	1	1	1
+3	2	3	1	1
+EXPLAIN SELECT * FROM t2 WHERE a=3 AND b=2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	8	const,const	1	Using index
+EXPLAIN SELECT * FROM t2 WHERE (a,b)=(3,2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	8	const,const	1	Using index
+SELECT * FROM t2 WHERE a=3 and b=2;
+a	b	c
+SELECT * FROM t2 WHERE (a,b)=(3,2);
+a	b	c
+EXPLAIN SELECT * FROM t1,t2 WHERE t2.a=t1.a AND t2.b=2 AND t2.c=1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	12	test.t1.a,const,const	1	Using index
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t2.a,(t2.b,t2.c))=(t1.a,(2,1));
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	12	test.t1.a,const,const	1	Using index
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`c` = 1) and (`test`.`t2`.`b` = 2) and (`test`.`t2`.`a` = `test`.`t1`.`a`))
+SELECT * FROM t1,t2 WHERE (t2.a,(t2.b,t2.c))=(t1.a,(2,1));
+a	b	a	b	c
+1	1	1	2	1
+1	2	1	2	1
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE t2.a=t1.a AND (t2.b,t2.c)=(2,1);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	PRIMARY	PRIMARY	8	NULL	6	Using index
+1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	12	test.t1.a,const,const	1	Using index
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t2`.`c` AS `c` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`c` = 1) and (`test`.`t2`.`b` = 2) and (`test`.`t2`.`a` = `test`.`t1`.`a`))
+SELECT * FROM t1,t2 WHERE t2.a=t1.a AND (t2.b,t2.c)=(2,1);
+a	b	a	b	c
+1	1	1	2	1
+1	2	1	2	1
+DROP TABLE t1,t2;

mysql-test/t/row.test

@@ -92,3 +92,50 @@ SELECT ROW(NULL,10) <=> ROW(3,NULL);
 #
 SELECT ROW(1,1,1) = ROW(1,1,1) as `1`, ROW(1,1,1) = ROW(1,2,1) as `0`, ROW(1,NULL,1) = ROW(2,2,1) as `0`, ROW(1,NULL,1) = ROW(1,2,2) as `0`, ROW(1,NULL,1) = ROW(1,2,1) as `null` ;
 select row(NULL,1)=(2,0);
+
+#
+# Bug #16081: row equalities are to be used for query optimizations  
+#
+
+CREATE TABLE t1 (a int, b int, PRIMARY KEY (a,b));
+INSERT INTO t1 VALUES (1,1), (2,1), (3,1), (1,2), (3,2), (3,3);
+
+EXPLAIN SELECT * FROM t1 WHERE a=3 AND b=2;
+EXPLAIN SELECT * FROM t1 WHERE (a,b)=(3,2);
+SELECT * FROM t1 WHERE a=3 and b=2;
+SELECT * FROM t1 WHERE (a,b)=(3,2);
+
+CREATE TABLE t2 (a int, b int, c int, PRIMARY KEY (a,b,c));
+INSERT INTO t2 VALUES
+  (1,1,2), (3,1,3), (1,2,2), (4,4,2),
+  (1,1,1), (3,1,1), (1,2,1);
+
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b=t2.b;
+EXPLAIN SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b);
+SELECT * FROM t1,t2 WHERE t1.a=t2.a and t1.b=t2.b;
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b);
+
+EXPLAIN SELECT * FROM t1,t2 WHERE t1.a=t2.a AND t1.b=2;
+EXPLAIN SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,2);
+SELECT * FROM t1,t2 WHERE t1.a=1 and t1.b=t2.b;
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,2);
+
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b+1);
+SELECT * FROM t1,t2 WHERE (t1.a,t1.b)=(t2.a,t2.b+1);
+
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t1.a-1,t1.b)=(t2.a-1,t2.b+1);
+SELECT * FROM t1,t2 WHERE (t1.a-1,t1.b)=(t2.a-1,t2.b+1);
+
+EXPLAIN SELECT * FROM t2 WHERE a=3 AND b=2;
+EXPLAIN SELECT * FROM t2 WHERE (a,b)=(3,2);
+SELECT * FROM t2 WHERE a=3 and b=2;
+SELECT * FROM t2 WHERE (a,b)=(3,2);
+
+EXPLAIN SELECT * FROM t1,t2 WHERE t2.a=t1.a AND t2.b=2 AND t2.c=1;
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE (t2.a,(t2.b,t2.c))=(t1.a,(2,1));
+SELECT * FROM t1,t2 WHERE (t2.a,(t2.b,t2.c))=(t1.a,(2,1));
+
+EXPLAIN EXTENDED SELECT * FROM t1,t2 WHERE t2.a=t1.a AND (t2.b,t2.c)=(2,1);
+SELECT * FROM t1,t2 WHERE t2.a=t1.a AND (t2.b,t2.c)=(2,1);
+
+DROP TABLE t1,t2;

sql/sql_list.h

@@ -94,9 +94,9 @@ class base_list :public Sql_alloc
   inline base_list() { empty(); }
   inline base_list(const base_list &tmp) :Sql_alloc()
   {
-    elements=tmp.elements;
-    first=tmp.first;
-    last=tmp.last;
+    elements= tmp.elements;
+    first= tmp.first;
+    last= elements ? tmp.last : &first;
   }
   inline base_list(bool error) { }
   inline bool push_back(void *info)

sql/sql_select.cc

@@ -6351,29 +6351,30 @@ Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
 
   
 /* 
-  Check whether an item is a simple equality predicate and if so
-  create/find a multiple equality for this predicate
+  Check whether an equality can be used to build multiple equalities
 
   SYNOPSIS
-    check_equality()
-    item       item to check
-    cond_equal multiple equalities that must hold together with the predicate
+    check_simple_equality()
+      left_item   left term of the quality to be checked
+      right_item  right term of the equality to be checked
+      item        equality item if the equality originates from a condition
+                  predicate, 0 if the equality is the result of row elimination
+      cond_equal  multiple equalities that must hold together with the equality
 
   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
-    (item=constant_item or item=field_item).
-    If this is the case the function looks a for a multiple equality
+    This function first checks whether the equality (left_item=right_item)
+    is a simple equality i.e. the one that equates a field with another field
+    or a constant (field=field_item or field=const_item).
+    If this is the case the function looks for a multiple equality
     in the lists referenced directly or indirectly by cond_equal inferring
     the given simple equality. If it doesn't find any, it builds a multiple
     equality that covers the predicate, i.e. the predicate can be inferred
-    from it.
+    from this multiple equality.
     The built multiple equality could be obtained in such a way:
     create a binary  multiple equality equivalent to the predicate, then
     merge it, if possible, with one of old multiple equalities.
     This guarantees that the set of multiple equalities covering equality
-    predicates will
-    be minimal.
+    predicates will be minimal.
 
   EXAMPLE
     For the where condition
@@ -6391,7 +6392,7 @@ Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
     and will transform *cond_equal into (ptr(CE),[Item_equal(f,e)]).
 
   NOTES
-    Now only fields that have the same type defintions (verified by
+    Now only fields that have the same type definitions (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 the constant propagation procedure.
@@ -6424,18 +6425,14 @@ Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
     copying would be much more complicated.
 
   RETURN
-    TRUE  - if the predicate is a simple equality predicate
-    FALSE - otherwise
+    TRUE    if the predicate is a simple equality predicate to be used
+            for building multiple equalities
+    FALSE   otherwise
 */
 
-static bool check_equality(Item *item, COND_EQUAL *cond_equal)
+static bool check_simple_equality(Item *left_item, Item *right_item,
+                                  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::REF_ITEM &&
       ((Item_ref*)left_item)->ref_type() == Item_ref::VIEW_REF)
   {
@@ -6463,9 +6460,6 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
     if (!left_field->eq_def(right_field))
       return FALSE;
 
-      if (left_field->eq(right_field))  /* f = f */
-        return TRUE;
-      
     /* Search for multiple equalities containing field1 and/or field2 */
     bool left_copyfl, right_copyfl;
     Item_equal *left_item_equal=
@@ -6473,6 +6467,10 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
     Item_equal *right_item_equal= 
                find_item_equal(cond_equal, right_field, &right_copyfl);
 
+    /* As (NULL=NULL) != TRUE we can't just remove the predicate f=f */
+    if (left_field->eq(right_field)) /* f = f */
+      return (!(left_field->maybe_null() && !left_item_equal)); 
+
     if (left_item_equal && left_item_equal == right_item_equal)
     {
       /* 
@@ -6555,7 +6553,16 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
       if (field_item->result_type() == STRING_RESULT)
       {
         CHARSET_INFO *cs= ((Field_str*) field_item->field)->charset();
-          if ((cs != ((Item_cond *) item)->compare_collation()) ||
+        if (!item)
+        {
+          Item_func_eq *eq_item;
+          if ((eq_item= new Item_func_eq(left_item, right_item)))
+            return FALSE;
+          eq_item->set_cmp_func();
+          eq_item->quick_fix_field();
+          item= eq_item;
+        }  
+        if ((cs != ((Item_func *) item)->compare_collation()) ||
             !cs->coll->propagate(cs, 0, 0))
           return FALSE;
       }
@@ -6584,10 +6591,116 @@ static bool check_equality(Item *item, COND_EQUAL *cond_equal)
       return TRUE;
     }
   }
+  return FALSE;
+}
+
+
+/* 
+  Convert row equalities into a conjunction of regular equalities
+
+  SYNOPSIS
+    check_row_equality()
+      left_row   left term of the row equality to be processed     
+      right_row  right term of the row equality to be processed
+      cond_equal multiple equalities that must hold together with the predicate
+      eq_list    results of conversions of row equalities that are not simple
+                 enough to form multiple equalities
+
+  DESCRIPTION
+    The function converts a row equality of the form (E1,...,En)=(E'1,...,E'n)
+    into a list of equalities E1=E'1,...,En=E'n. For each of these equalities
+    Ei=E'i the function checks whether it is a simple equality or a row equality.
+    If it is a simple equality it is used to expand multiple equalities of
+    cond_equal. If it is a row equality it converted to a sequence of equalities
+    between row elements. If Ei=E'i is neither a simple equality nor a row
+    equality the item for this predicate is added to eq_list.
+
+  RETURN
+    TRUE    if conversion has succeeded (no fatal error) 
+    FALSE   otherwise  
+*/
+ 
+static bool check_row_equality(Item *left_row, Item_row *right_row,
+                               COND_EQUAL *cond_equal, List<Item>* eq_list)
+{ 
+  uint n= left_row->cols();
+  for (uint i= 0 ; i < n; i++)
+  {
+    bool is_converted;
+    Item *left_item= left_row->el(i);
+    Item *right_item= right_row->el(i);
+    if (left_item->type() == Item::ROW_ITEM &&
+        right_item->type() == Item::ROW_ITEM)
+      is_converted= check_row_equality((Item_row *) left_item,
+	                               (Item_row *) right_item,
+				       cond_equal, eq_list);
+    else 
+      is_converted= check_simple_equality(left_item, right_item, 0, cond_equal);
+
+    if (!is_converted)  
+    {
+      Item_func_eq *eq_item;
+      if (!(eq_item= new Item_func_eq(left_item, right_item)))
+        return FALSE;
+      eq_item->set_cmp_func();
+      eq_item->quick_fix_field();
+      eq_list->push_back(eq_item);
+    }
+  }
+  return TRUE;
+}
+
+
+/* 
+  Eliminate row equalities and form multiple equalities predicates 
+
+  SYNOPSIS
+    check_equality()
+      item       predicate to process     
+      cond_equal multiple equalities that must hold together with the predicate
+      eq_list    results of conversions of row equalities that are not simple
+                 enough to form multiple equalities
+
+  DESCRIPTION
+    This function checks whether the item is a simple equality
+    i.e. the one that equates a field with another field or a constant
+    (field=field_item or field=constant_item), or, a row equality.
+    For a simple equality the function looks for a multiple equality
+    in the lists referenced directly or indirectly by cond_equal inferring
+    the given simple equality. If it doesn't find any, it builds/expands
+    multiple equality that covers the predicate.
+    Row equalities are eliminated substituted for conjunctive regular equalities
+    which are treated in the same way as original equality predicates.
+
+  RETURN
+    TRUE   if re-writing rules have been applied
+    FALSE  otherwise, i.e.
+           if the predicate is not an equality,
+           or, if the equality is neither a simple one nor a row equality,
+           or, if the procedure fails by a fatal error.
+*/
+
+static bool check_equality(Item *item, COND_EQUAL *cond_equal,
+                           List<Item> *eq_list)
+{
+  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::ROW_ITEM &&
+        right_item->type() == Item::ROW_ITEM)
+      return check_row_equality((Item_row *) left_item,
+                                (Item_row *) right_item,
+                                cond_equal, eq_list);
+    else 
+      return check_simple_equality(left_item, right_item, item, cond_equal);
   } 
   return FALSE;
 }
 
+                          
 /* 
   Replace all equality predicates in a condition by multiple equality items
 
@@ -6659,10 +6772,12 @@ static COND *build_equal_items_for_cond(COND *cond,
   Item_equal *item_equal;
   uint members;
   COND_EQUAL cond_equal;
+  COND *new_cond;
   cond_equal.upper_levels= inherited;
 
   if (cond->type() == Item::COND_ITEM)
   {
+    List<Item> eq_list;
     bool and_level= ((Item_cond*) cond)->functype() ==
       Item_func::COND_AND_FUNC;
     List<Item> *args= ((Item_cond*) cond)->argument_list();
@@ -6685,7 +6800,7 @@ static COND *build_equal_items_for_cond(COND *cond,
           structure here because it's restored before each
           re-execution of any prepared statement/stored procedure.
         */
-        if (check_equality(item, &cond_equal))
+        if (check_equality(item, &cond_equal, &eq_list))
           li.remove();
       }
 
@@ -6732,10 +6847,14 @@ static COND *build_equal_items_for_cond(COND *cond,
       }
     }
     if (and_level)
+    {
+      args->concat(&eq_list);
       args->concat((List<Item> *)&cond_equal.current_level);
     }
+  }
   else if (cond->type() == Item::FUNC_ITEM)
   {
+    List<Item> eq_list;
     /*
       If an equality predicate forms the whole and level,
       we call it standalone equality and it's processed here.
@@ -6746,13 +6865,46 @@ static COND *build_equal_items_for_cond(COND *cond,
       for WHERE a=b AND c=d AND (b=c OR d=5)
       b=c is replaced by =(a,b,c,d).  
      */
-    if (check_equality(cond, &cond_equal) &&
-        (item_equal= cond_equal.current_level.pop()))
+    if (check_equality(cond, &cond_equal, &eq_list))
+    {
+      int n= cond_equal.current_level.elements + eq_list.elements;
+      if (n == 0)
+        return new Item_int((longlong) 1,1);
+      else if (n == 1)
+      {
+        if ((item_equal= cond_equal.current_level.pop()))
         {
           item_equal->fix_length_and_dec();
           item_equal->update_used_tables();
           return item_equal;
 	}
+        else
+          return eq_list.pop();
+      }
+      else
+      {
+        /* 
+          Here a new AND level must be created. It can happen only
+          when a row equality is processed as a standalone predicate.
+	*/
+        Item_cond_and *and_cond= new Item_cond_and(eq_list);
+        and_cond->quick_fix_field();
+        List<Item> *args= and_cond->argument_list();
+        List_iterator_fast<Item_equal> it(cond_equal.current_level);
+        while ((item_equal= it++))
+        {
+          item_equal->fix_length_and_dec();
+          item_equal->update_used_tables();
+          members= item_equal->members();
+          if (cond_equal.max_members < members)
+            cond_equal.max_members= members; 
+        }
+        and_cond->cond_equal= cond_equal;
+        args->concat((List<Item> *)&cond_equal.current_level);
+        
+        return and_cond;
+      }
+    }
     /* 
       For each field reference in cond, not from equal item predicates,
       set a pointer to the multiple equality it belongs to (if there is any)
@@ -7038,7 +7190,7 @@ static Item *eliminate_item_equal(COND *cond, COND_EQUAL *upper_levels,
 
 /* 
   Substitute every field reference in a condition by the best equal field 
-  and eliminate all multiplle equality predicates
+  and eliminate all multiple equality predicates
  
   SYNOPSIS
     substitute_for_best_equal_field()