Wrong result with derived_with_keys, correlated subquery

[Philip Stoev]

The following query:

SELECT * FROM t1 WHERE t1.b IN ( SELECT v2.a FROM v2 WHERE v2.b = t1.a );

returns no rows when executed with derived_with_keys and

a b
5 4

when executed otherwise.

explain:

id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
2 DEPENDENT SUBQUERY <derived3> ref key0 key0 5 test.t1.a 2 Using where
3 DERIVED t2 ALL NULL NULL NULL NULL 2

minimal switch: derived_with_keys=ON;

full 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=off,derived_merge=off,derived_with_keys=on,firstmatch=off,loosescan=off,materialization=off,in_to_exists=on,semijoin=off,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=off,semijoin_with_cache=off,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on

bzr version-info
revision-id: <email address hidden>
date: 2011-10-13 11:23:59 +0200
build-date: 2011-10-13 14:15:52 +0300
revno: 3232
branch-nick: maria-5.3

test case:

CREATE TABLE t1 ( a int , b int ) ;
INSERT INTO t1 VALUES (5,4),(9,8);

CREATE TABLE t2 ( a int , b int ) ;
INSERT INTO t2 VALUES (4,5),(5,1);

CREATE ALGORITHM=TEMPTABLE VIEW v2 AS SELECT * FROM t2;
SET SESSION optimizer_switch='derived_with_keys=ON';
SELECT * FROM t1 WHERE t1.b IN ( SELECT v2.a FROM v2 WHERE v2.b = t1.a );

[Igor Babaev (igorb-seattle)]

This bug was fixed by the patch for bug #874006.