Details
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Type:
Bug
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Status: Closed
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Priority:
Minor
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Resolution: Fixed
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Affects Version/s: 5.5.20, 5.3.3, 5.3.4
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Fix Version/s: None
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Component/s: None
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Labels:None
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_level<=2. The latter is the correct result.
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`.`alias1`.`b` AS `b` from `test`.`t1` `alias1` semi join (`test`.`t1` join `test`.`t2`) join `test`.`t1` `alias2` where (`test`.`alias2`.`a` = `test`.`alias1`.`b`) 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`.`alias1`.`b` AS `b` from `test`.`t1` `alias1` semi join (`test`.`t1` join `test`.`t2`) join `test`.`t1` `alias2` where (`test`.`alias2`.`a` = `test`.`alias1`.`b`) 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=on,materialization=on,join_cache_hashed=on
Full optimizer_switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on
Test case:
SET optimizer_switch = 'semijoin=on,materialization=on,join_cache_hashed=on';
SET join_cache_level = 3;
CREATE TABLE t1 ( a INT, b INT, KEY(a) );
INSERT INTO t1 VALUES
(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7);
CREATE TABLE t2 ( c INT );
INSERT INTO t2 VALUES (1),(2),(3),(4),(5),(6),(7);
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
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This bug has also been filed in LP as https://bugs.launchpad.net/maria/+bug/912513
bzr version-info
revision-id: igor@askmonty.org-20120103040636-nc6o55vsxqadd1n0
date: 2012-01-02 20:06:36 -0800
build-date: 2012-01-05 23:33:41 +0400
revno: 3376
branch-nick: maria-5.3