mirror/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2026-05-14 19:07:15 +02:00
Code Issues Projects Releases Packages Wiki Activity

Bug#46051: Incorrectly market field caused wrong result.

Browse source 
In a subselect all fields from outer selects are marked as dependent on
selects they are belong to. In some cases optimizer substitutes it for an
equivalent expression. For example "a_field IN (SELECT outer_field)" is
substituted with "a_field = outer_field". As we moved the outer_field to the
upper select it's not really outer anymore. But it was left marked as outer.
If exists an index over a_field optimizer choose wrong execution plan and thus
return wrong result.

Now the Item_in_subselect::single_value_transformer function removes dependent
marking from fields when a subselect is optimized away.

mysql-test/r/subselect.result:
  Added a test case for the bug#46051.
mysql-test/t/subselect.test:
  Added a test case for the bug#46051.
sql/item_subselect.cc:
  Bug#46051: Incorrectly market field caused wrong result.
  Now the Item_in_subselect::single_value_transformer function removes dependent
  marking from fields when a subselect is optimized away.
This commit is contained in:
Evgeny Potemkin 2009-07-16 19:43:46 +04:00
commit 63e6a59d73
3 changed files with 50 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

4
sql/item_subselect.cc
View file

@ -1145,6 +1145,10 @@ Item_in_subselect::single_value_transformer(JOIN *join,
else
{
// it is single select without tables => possible optimization
// remove the dependence mark since the item is moved to upper
// select and is not outer anymore.
item->walk(&Item::remove_dependence_processor,
(byte *) select_lex->outer_select());
item= func->create(left_expr, item);
// fix_field of item will be done in time of substituting
substitution= item;