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Apply Jorgen Loland's fix: Bug#45221: Query "SELECT pk FROM C WHERE pk IN (SELECT int_key)" failing

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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.
This commit is contained in:
Sergey Petrunya 2010-02-12 00:58:23 +03:00
parent 64e63fb85d
commit 5c836140a5
2 changed files with 26 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
mysql-test/r/group_by.result
View file

@ -1542,8 +1542,8 @@ id select_type table type possible_keys key key_len ref rows Extra
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 @@ id select_type table type possible_keys key key_len ref rows Extra
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

24
sql/item_cmpfunc.h
View file

@ -1715,14 +1715,34 @@ inline bool is_cond_or(Item *item)
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); }
};