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Fixed bug #21727.

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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.
This commit is contained in:
igor@rurik.mysql.com
2006-10-31 17:31:56 -08:00
parent 17eb0b353e
commit 2a7acba7e1
12 changed files with 124 additions and 16 deletions
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2
sql/mysql_priv.h
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@ -1465,7 +1465,7 @@ void end_read_record(READ_RECORD *info);
ha_rows filesort(THD *thd, TABLE *form,struct st_sort_field *sortorder,
uint s_length, SQL_SELECT *select,
ha_rows max_rows, ha_rows *examined_rows);
void filesort_free_buffers(TABLE *table);
void filesort_free_buffers(TABLE *table, bool full);
void change_double_for_sort(double nr,byte *to);
double my_double_round(double value, int dec, bool truncate);
int get_quick_record(SQL_SELECT *select);