At file:///home/psergey/dev/maria-5.3-subqueries-r6/ ------------------------------------------------------------ revno: 2752 revision-id: psergey@askmonty.org-20100211215823-63ikirl70ztmlk05 parent: psergey@askmonty.org-20100211215602-irdyu314ddwew1xd committer: Sergey Petrunya <psergey@askmonty.org> branch nick: maria-5.3-subqueries-r6 timestamp: Fri 2010-02-12 00:58:23 +0300 message: Apply Jorgen Loland's fix: Bug#45221: Query "SELECT pk FROM C WHERE pk IN (SELECT int_key)" failing XOR conditions are not optimized, and Item_cond_xor therefore acts like type Func_item even though it inherits from Item_cond. A subtle difference between Item_func and Item_cond is that you can get the children Items from the former by calling arguments(), and from the latter by calling argument_list(). However, since Item_cond_xor inherits from Item_cond, arguments() did not return any Items. The fact that Item_cond_xor::arguments() did not return it's children items lead to a problem for make_cond_for_index(); the method accepted that XOR items on unindexed columns were pushed using ICP. ICP evaluation of non-indexed columns does not (and should not) work. The fix for this bug is to make Item_cond_xor return it's children items when the arguments() method is used. This makes Item_cond_xor behave more like Item_func and in turn allows make_cond_for_index() to discover any conflicting children Items. This is a temporary fix and should be removed when Item_cond_xor is optimized. === modified file 'mysql-test/r/group_by.result' --- a/mysql-test/r/group_by.result 2009-02-26 17:17:06 +0000 +++ b/mysql-test/r/group_by.result 2010-02-11 21:58:23 +0000 @@ -1542,8 +1542,8 @@ EXPLAIN SELECT 1 FROM t1 WHERE a IN (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2)); id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t1 index NULL PRIMARY 4 NULL 144 Using where; Using index -2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 144 Using where +1 PRIMARY t1 index PRIMARY,i2 PRIMARY 4 NULL 144 Using index +1 PRIMARY t1 ALL NULL NULL NULL NULL 144 Using where; FirstMatch(t1) CREATE TABLE t2 (a INT, b INT, KEY(a)); INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4); EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2; @@ -1555,8 +1555,8 @@ EXPLAIN SELECT 1 FROM t2 WHERE a IN (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2)); id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t2 index NULL a 5 NULL 4 Using where; Using index -2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 144 Using where +1 PRIMARY t2 index a a 5 NULL 4 Using index +1 PRIMARY t1 ALL NULL NULL NULL NULL 144 Using where; FirstMatch(t2) SHOW VARIABLES LIKE 'old'; Variable_name Value old OFF === modified file 'sql/item_cmpfunc.h' --- a/sql/item_cmpfunc.h 2010-01-17 14:55:08 +0000 +++ b/sql/item_cmpfunc.h 2010-02-11 21:58:23 +0000 @@ -1715,14 +1715,34 @@ class Item_cond_xor :public Item_cond { public: - Item_cond_xor() :Item_cond() {} - Item_cond_xor(Item *i1,Item *i2) :Item_cond(i1,i2) {} + Item_cond_xor(Item *i1,Item *i2) :Item_cond(i1,i2) + { + /* + Items must be stored in args[] as well because this Item_cond is + treated as a FUNC_ITEM (see type()). I.e., users of it will get + it's children by calling arguments(), not argument_list(). This + is a temporary solution until XOR is optimized and treated like + a full Item_cond citizen. + */ + arg_count= 2; + args= tmp_arg; + args[0]= i1; + args[1]= i2; + } enum Functype functype() const { return COND_XOR_FUNC; } /* TODO: remove the next line when implementing XOR optimization */ enum Type type() const { return FUNC_ITEM; } longlong val_int(); const char *func_name() const { return "xor"; } void top_level_item() {} + /* Since child Items are stored in args[], Items cannot be added. + However, since Item_cond_xor is treated as a FUNC_ITEM (see + type()), the methods below should never be called. + */ + bool add(Item *item) { DBUG_ASSERT(FALSE); return FALSE; } + bool add_at_head(Item *item) { DBUG_ASSERT(FALSE); return FALSE; } + bool add_at_head(List<Item> *nlist) { DBUG_ASSERT(FALSE); return FALSE; } + void copy_andor_arguments(THD *thd, Item_cond *item) { DBUG_ASSERT(FALSE); } };