[#MDEV-245] Exists2In: Wrong result (extra rows) with exists_to_in=ON, materialization=OFF, NOT EXISTS subquery

The following query

SELECT * FROM t1 WHERE NOT EXISTS ( SELECT * FROM t2 WHERE b = a )

on the test data returns 3 rows if executed with exists_to_in=on, materialization=off, and 2 rows otherwise. The correct result is 2 rows.

bzr version-info

revision-id: sanja@montyprogram.com-20120430093355-4yrpta86g97g6rhb

date: 2012-04-30 12:33:55 +0300

build-date: 2012-05-02 22:58:36 +0400

revno: 3390

optimizer_switch (default + exists_to_in=on + materialization=off):

index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=off,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,extended_keys=off,exists_to_in=on

EXPLAIN with optimizer_switch = default + exists_to_in=on + materialization=off (wrong result):

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where

2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where

Warnings:

Note	1276	Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1

Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (not(((`test`.`t1`.`a` is not null) and <exists>(select `test`.`t2`.`b` from `test`.`t2` where ((`test`.`t2`.`b` is not null) and (<cache>(`test`.`t1`.`a`) = `test`.`t2`.`b`))))))

EXPLAIN with optimizer_switch = default + exists_to_in=off + materialization=off (correct result):

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where

2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where

Warnings:

Note	1276	Field or reference 'test.t1.a' of SELECT #2 was resolved in SELECT #1

Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (not(<expr_cache><`test`.`t1`.`a`>(exists(select 1 from `test`.`t2` where (`test`.`t2`.`b` = `test`.`t1`.`a`)))))

Test case:

SET optimizer_switch='materialization=off';

CREATE TABLE t1 ( a INT ) ;

INSERT INTO t1 VALUES (0),(8),(1);

CREATE TABLE t2 ( b INT ) ;

INSERT INTO t2 VALUES (1),(2),(3);

SELECT * FROM t1 WHERE NOT EXISTS ( SELECT * FROM t2 WHERE b = a );

Expected result:

# a

# ---

# 0

# 8

Actual result:

# a

# ---

# 0

# 8

# 1

[MDEV-245] Exists2In: Wrong result (extra rows) with exists_to_in=ON, materialization=OFF, NOT EXISTS subquery Created: 2012-05-02 Updated: 2012-07-18 Resolved: 2012-07-18
Status:	Closed
Project:	MariaDB Server
Component/s:	None
Affects Version/s:	None
Fix Version/s:	10.0.0

[MDEV-245] Exists2In: Wrong result (extra rows) with exists_to_in=ON, materialization=OFF, NOT EXISTS subquery Created: 2012-05-02 Updated: 2012-07-18 Resolved: 2012-07-18