database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

Bug #27807.

Browse Source 
Non-correlated scalar subqueries may get executed
in EXPLAIN at the optimization phase if they are
part of a right hand sargable expression.
If the scalar subquery uses a temp table to 
materialize its results it will replace the 
subquery structure from the parser with a simple
select from the materialization table.
As a result the EXPLAIN will crash as the 
temporary materialization table is not to be shown
in EXPLAIN at all.
Fixed by preserving the original query structure
right after calling optimize() for scalar subqueries
with temp tables executed during EXPLAIN.


mysql-test/r/subselect.result:
  Bug #27807: test case
mysql-test/t/subselect.test:
  Bug #27807: test case
sql/item_subselect.cc:
  Bug #27807: preserve the join structure
sql/sql_select.cc:
  Bug #27807: introduce initialization function for tmp_join
sql/sql_select.h:
  Bug #27807: introduce initialization function for tmp_join
This commit is contained in:
unknown
2007-05-04 10:48:51 +03:00
parent 5a35befff5
commit 0ad4e1b2a6
5 changed files with 62 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
mysql-test/r/subselect.result
View File

@ -4012,3 +4012,11 @@ WHERE (SELECT COUNT(t0.b) FROM t1 t WHERE t.b>20) GROUP BY a;
ERROR HY000: Invalid use of group function
SET @@sql_mode=default;
DROP TABLE t1;
CREATE TABLE t1 (a int, b int, KEY (a));
INSERT INTO t1 VALUES (1,1),(2,1);
EXPLAIN SELECT 1 FROM t1 WHERE a = (SELECT COUNT(*) FROM t1 GROUP BY b);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ref a a 5 const 1 Using where; Using index
2 SUBQUERY t1 ALL NULL NULL NULL NULL 2 Using temporary; Using filesort
DROP TABLE t1;
End of 5.0 tests.

10
mysql-test/t/subselect.test
View File

@ -2845,3 +2845,13 @@ SELECT a FROM t1 t0
SET @@sql_mode=default;
DROP TABLE t1;
#
# Bug #27807: Server crash when executing subquery with EXPLAIN
#
CREATE TABLE t1 (a int, b int, KEY (a));
INSERT INTO t1 VALUES (1,1),(2,1);
EXPLAIN SELECT 1 FROM t1 WHERE a = (SELECT COUNT(*) FROM t1 GROUP BY b);
DROP TABLE t1;
--echo End of 5.0 tests.