At file:///home/psergey/dev/maria-5.3-subqueries-r3/
------------------------------------------------------------
revno: 2756
revision-id: psergey@askmonty.org-20100208133030-e4zjy15b7o14ud8c
parent: psergey@askmonty.org-20100208132741-nj9zq7z8nwlfwchq
committer: Sergey Petrunya
branch nick: maria-5.3-subqueries-r3
timestamp: Mon 2010-02-08 15:30:30 +0200
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 'sql/item_cmpfunc.h'
--- a/sql/item_cmpfunc.h 2010-01-17 14:55:08 +0000
+++ b/sql/item_cmpfunc.h 2010-02-08 13:30:30 +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); }
};
