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MDEV-17411 Wrong WHERE optimization with simple CASE and searched CASE

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This commit is contained in:
Alexander Barkov
2018-10-11 13:39:53 +04:00
parent 30629e196d
commit 4de0d920be
7 changed files with 66 additions and 9 deletions
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27
mysql-test/main/case.result
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@ -546,5 +546,32 @@ Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = 'a'
DROP TABLE t1;
#
# MDEV-17411 Wrong WHERE optimization with simple CASE and searched CASE
#
CREATE TABLE t1 (a INT, b INT, KEY(a));
INSERT INTO t1 VALUES (1,1),(2,2),(3,3);
SELECT * FROM t1 WHERE CASE a WHEN b THEN 1 END=1;
a b
1 1
2 2
3 3
SELECT * FROM t1 WHERE CASE WHEN a THEN b ELSE 1 END=3;
a b
3 3
SELECT * FROM t1 WHERE
CASE a WHEN b THEN 1 END=1 AND
CASE WHEN a THEN b ELSE 1 END=3;
a b
3 3
EXPLAIN EXTENDED
SELECT * FROM t1 WHERE
CASE a WHEN b THEN 1 END=1 AND
CASE WHEN a THEN b ELSE 1 END=3;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (case `test`.`t1`.`a` when `test`.`t1`.`b` then 1 end) = 1 and (case when `test`.`t1`.`a` then `test`.`t1`.`b` else 1 end) = 3
DROP TABLE t1;
#
# End of 10.3 test
#