Wrong result (missing rows) with join_cache_hashed+materialization+semijoin=on, join_cache_level > 2, JOIN, IN subquery
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
MariaDB |
Fix Released
|
Critical
|
Sergey Petrunia |
Bug Description
The following query
SELECT alias1.* FROM
t1 AS alias1 INNER JOIN t1 AS alias2
ON alias2.a = alias1.b
WHERE alias1.b IN (
SELECT a FROM t1, t2
)
on the test data returns a single row with join_cache_level>2, and 7 rows with join_cache_
bzr version-info
revision-id: <email address hidden>
date: 2012-01-02 20:06:36 -0800
build-date: 2012-01-05 23:33:41 +0400
revno: 3376
branch-nick: maria-5.3
Reproducible on 5.3.2 and 5.3.3 releases, current 5.3, 5.5.
EXPLAIN with join_cache_level=3 (wrong result)
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY alias1 ALL NULL NULL NULL NULL 7 100.00
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 5 func 1 100.00
1 PRIMARY alias2 hash_index a #hash#a:a 5:5 test.t1.a 7 28.57 Using where; Using join buffer (flat, BNLH join)
2 MATERIALIZED t1 index a a 5 NULL 7 100.00 Using where; Using index
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00
Warnings:
Note 1003 select `test`.`alias1`.`a` AS `a`,`test`
SELECT alias1.* FROM
t1 AS alias1 INNER JOIN t1 AS alias2
ON alias2.a = alias1.b
WHERE alias1.b IN (
SELECT a FROM t1, t2
)
EXPLAIN with join_cache_level=2 (correct result):
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY alias1 ALL NULL NULL NULL NULL 7 100.00 Using where
1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 5 func 1 100.00
1 PRIMARY alias2 ref a a 5 test.alias1.b 2 100.00 Using index
2 MATERIALIZED t1 index a a 5 NULL 7 100.00 Using index
2 MATERIALIZED t2 ALL NULL NULL NULL NULL 7 100.00
Warnings:
Note 1003 select `test`.`alias1`.`a` AS `a`,`test`
SELECT alias1.* FROM
t1 AS alias1 INNER JOIN t1 AS alias2
ON alias2.a = alias1.b
WHERE alias1.b IN (
SELECT a FROM t1, t2
)
Minimal optimizer_switch: semijoin=
Full optimizer_switch: index_merge=
Test case:
SET optimizer_switch = 'semijoin=
SET join_cache_level = 3;
CREATE TABLE t1 ( a INT, b INT, KEY(a) );
INSERT INTO t1 VALUES
(1,1)
CREATE TABLE t2 ( c INT );
INSERT INTO t2 VALUES (1),(2)
SELECT alias1.* FROM
t1 AS alias1 INNER JOIN t1 AS alias2
ON alias2.a = alias1.b
WHERE alias1.b IN (
SELECT a FROM t1, t2
);
Expected result:
a b
1 1
2 2
3 3
4 4
5 5
6 6
7 7
Result:
a b
7 7
Changed in maria: | |
status: | New → Confirmed |
Changed in maria: | |
importance: | Undecided → Critical |
assignee: | Igor Babaev (igorb-seattle) → Sergey Petrunia (sergefp) |
Changed in maria: | |
status: | Confirmed → Fix Committed |
Changed in maria: | |
status: | Fix Committed → Fix Released |
This bug has also been filed in JIRA as MDEV-71.