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| author | igor@rurik.mysql.com <> | 2006-10-31 17:31:56 -0800 |
|---|---|---|
| committer | igor@rurik.mysql.com <> | 2006-10-31 17:31:56 -0800 |
| commit | 2a7acba7e10197ec4a651ae828ff51c0a2ff4747 (patch) | |
| tree | b8cf0e80a37eba77a6cccf9e41a8871266533675 /sql/item_subselect.h | |
| parent | 17eb0b353e5a112e1d0005b71190c1e3278e0583 (diff) | |
| download | mariadb-git-2a7acba7e10197ec4a651ae828ff51c0a2ff4747.tar.gz | |
Fixed bug #21727.
This is a performance issue for queries with subqueries evaluation
of which requires filesort.
Allocation of memory for the sort buffer at each evaluation of a
subquery may take a significant amount of time if the buffer is rather big.
With the fix we allocate the buffer at the first evaluation of the
subquery and reuse it at each subsequent evaluation.
Diffstat (limited to 'sql/item_subselect.h')
| -rw-r--r-- | sql/item_subselect.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sql/item_subselect.h b/sql/item_subselect.h index 45df4f3880d..1a8111069e6 100644 --- a/sql/item_subselect.h +++ b/sql/item_subselect.h @@ -114,6 +114,7 @@ public: single select and union subqueries only. */ bool is_evaluated() const; + bool is_uncacheable() const; /* Used by max/min subquery to initialize value presence registration @@ -428,3 +429,9 @@ inline bool Item_subselect::is_evaluated() const return engine->is_executed(); } +inline bool Item_subselect::is_uncacheable() const +{ + return engine->uncacheable(); +} + + |