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.


mysql-test/r/subselect.result:
  Added a test case for bug #21727.
mysql-test/t/subselect.test:
  Added a test case for bug #21727.
sql/item_subselect.h:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added an implementation for Item_subselect::is_uncacheable()
  returning TRUE if the engine if the subselect is uncacheable.
sql/mysql_priv.h:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added a new boolean parameter to the filesort_free_buffers procedure.
  If the value of this parameter is TRUE the procedure frees the sort_keys
  buffpek buffers.
sql/records.cc:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added a new boolean parameter to the filesort_free_buffers procedure.
  If the value of this parameter is TRUE the procedure frees the sort_keys
  buffpek buffers.
sql/sql_base.cc:
  Fixed bug #21727.
  Made sure that st_table::pos_in_table_list would be always initialized.
sql/sql_select.cc:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added a new boolean parameter to the filesort_free_buffers procedure.
  If the value of this parameter is TRUE the procedure frees the sort_keys
  buffpek buffers.
sql/sql_show.cc:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added a new boolean parameter to the filesort_free_buffers procedure.
  If the value of this parameter is TRUE the procedure frees the sort_keys
  buffpek buffers.
sql/sql_table.cc:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Cleanup.
sql/table.cc:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added st_table_list::in_subselect() returning for a table the subselect that 
  contains the FROM list this table is taken from (if there is any).
sql/table.h:
  Fixed bug #21727.
  This is a performance issue for queries with subqueries evaluation
  of which requires filesort.
  Added fields for sort_keys and buffpek buffers to the FILESORT_INFO structure.

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h
index ea3b3a9bd83..13e44b49b53 100644
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@@ -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);