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Description
The problem appeared in 5.5 tree with the following revision:
revno: 3843
revision-id: psergey@askmonty.org-20130731132452-4qb11t56i2jw16aa
parent: psergey@askmonty.org-20130731093701-10tmxhe668f3u1lx
committer: Sergey Petrunya <psergey@askmonty.org>
branch nick: 5.5
timestamp: Wed 2013-07-31 17:24:52 +0400
message:
MDEV-4817: Optimizer fails to optimize expression of the form 'FOO' IS NULL
- Modify the way Item_cond::fix_fields() and Item_cond::eval_not_null_tables()
calculate bitmap for Item_cond_or::not_null_tables():
if they see a "... OR inexpensive_const_false_item OR ..." then the item can
be ignored.
- Updated test results. There can be more warnings produced since parts of WHERE
are evaluated more times.
Test case:
CREATE TABLE t1 (a INT, b INT, KEY(b)); INSERT INTO t1 VALUES (1,2),(3,4); PREPARE stmt FROM " SELECT SUM( alias1.a ) AS field1, alias2.a AS field2 FROM t1 AS alias1 JOIN t1 AS alias2 ON ( alias2.a = alias1.a ) WHERE 1 NOT IN ( SELECT b FROM t1 ) GROUP BY field2 HAVING field1 != 1 "; EXECUTE stmt; EXECUTE stmt; DEALLOCATE PREPARE stmt; DROP TABLE t1;
MariaDB [test]> EXECUTE stmt; +--------+--------+ | field1 | field2 | +--------+--------+ | 3 | 3 | +--------+--------+ 1 row in set (0.01 sec) MariaDB [test]> EXECUTE stmt; ERROR 1247 (42S22): Reference 'field1' not supported (reference to group function)
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