Hi!
18.07.2011 23:45, [email protected] пишет:
At file:///home/tsk/mprog/src/5.3-work/
------------------------------------------------------------
revno: 3115
revision-id: [email protected]
parent: [email protected]
fixes bug(s): https://launchpad.net/bugs/782305
committer: [email protected]
branch nick: 5.3-work
timestamp: Mon 2011-07-18 23:45:38 +0300
message:
Fix bug lp:782305
Analysis:
Both the wrong result and the valgrind warning were a result
of incomplete cleanup of the MIN/MAX subquery rewrite. At the
first execution of the query, the non-aggregate subquery is
transformed into an aggregate MIN/MAX subquery. During the
fix_fields phase of the MIN/MAX function, it sets the property
st_select_lex::with_sum_func to true.
The second execution of the query finds this flag to be ON.
When optimization reaches the same MIN/MAX subquery
transformation, it tests if the subquery is an aggregate or not.
Since select_lex->with_sum_func == true from the previous
execution, the transformation executes the second branch that
handles aggregate subqueries. This substitutes the subquery
Item into a Item_maxmin_subselect. At the same time elsewhere
it is assumed that the subquery Item is of type
Item_allany_subselect. Ultimately this results in casting the
actual object to the wrong class, and calling the wrong
any_value() method from empty_underlying_subquery().
Solution:
Cleanup the st_select_lex::with_sum_func property in the case
when the MIN/MAX transformation was performed for a non-aggregate
subquery, so that the transformation can be repeated.
The patch is OK.
SUBS_MAXMIN_ENGINE is really good name, thank you!
[skip]
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