Wrong result with Aggregate + DISTINCT in FROM subquery in maria-5.3, 5.2

[Philip Stoev]

Reproducible in maria-5.3, maria-5.2. Not reproducible in MySQL 5.5 .

The following query:

SELECT * FROM ( SELECT SUM( DISTINCT f11 ) FROM t1) AS a1;

returns (0) even though the FROM subquery returns (NULL);

Test case:

USE test;
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 ( f11 int NOT NULL ) ;
SELECT * FROM ( SELECT SUM( DISTINCT f11 ) FROM t1) AS a1;

explain in maria 5.3:

+----+-------------+------------+--------+---------------+------+---------+------+------+--------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+---------------+------+---------+------+------+--------------------------------+
| 1 | PRIMARY | <derived2> | system | NULL | NULL | NULL | NULL | 1 | |
| 2 | DERIVED | NULL | NULL | NULL | NULL | NULL | NULL | NULL | no matching row in const table |
+----+-------------+------------+--------+---------------+------+---------+------+------+--------------------------------+

explain in mysql 5.5:

+----+-------------+------------+--------+---------------+------+---------+------+------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+---------------+------+---------+------+------+-------+
| 1 | PRIMARY | <derived2> | system | NULL | NULL | NULL | NULL | 1 | |
| 2 | DERIVED | t1 | ALL | NULL | NULL | NULL | NULL | 1 | |
+----+-------------+------------+--------+---------------+------+---------+------+------+-------+

[Philip Stoev (pstoev-askmonty)]

Also reproducible with MySQL 5.1.56