Details
Description
The test case below returns different results when a query is run with a MERGE view comparing to a TEMPTABLE view or a base table. I believe that the TEMPTABLE/base table result is correct, even although the result with the MERGE view might look more "natural".
The difference seems fresh, it appeared in maria/5.3 tree since revno 3592.
Test case:
CREATE TABLE t1 (a INT NOT NULL) ENGINE=MyISAM; INSERT INTO t1 VALUES (4),(7),(0); CREATE TABLE t2 (b INT NOT NULL) ENGINE=MyISAM; INSERT INTO t2 VALUES (1),(2); CREATE TABLE t3 (c INT NOT NULL) ENGINE=MyISAM; INSERT INTO t3 VALUES (4),(6),(3); CREATE TABLE t4 (d INT NOT NULL) ENGINE=MyISAM; INSERT INTO t4 VALUES (4),(5),(3); CREATE TABLE tv (e INT NOT NULL) ENGINE=MyISAM; INSERT INTO tv VALUES (1),(3); CREATE ALGORITHM=TEMPTABLE VIEW v_temptable AS SELECT * FROM tv; CREATE ALGORITHM=MERGE VIEW v_merge AS SELECT * FROM tv; SELECT * FROM t1, t2 WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_temptable ON (c = e) WHERE c <> b ) AND a < b; SELECT * FROM t1, t2 WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_merge ON (c = e) WHERE c <> b ) AND a < b;
Results from maria/5.3 revno 3599:
WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_temptable ON (c = e) WHERE c <> b ) AND a < b; a b SELECT * FROM t1, t2 WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_merge ON (c = e) WHERE c <> b ) AND a < b; a b 0 1 0 2
Default 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
EXPLAINs (with the default optimizer switch):
EXPLAIN EXTENDED SELECT * FROM t1, t2 WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_temptable ON (c = e) WHERE c <> b ) AND a < b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3100.00 Using where 2 DEPENDENT SUBQUERY <derived3> ref key0 key0 4 test.t3.c 2 100.00 Using where 3 DERIVED tv ALL NULL NULL NULL NULL 2 100.00 Warnings: Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1 Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where ((not(<expr_cache><`test`.`t1`.`a`,`test`.`t2`.`b`>(<in_optimizer>(`test`.`t1`.`a`,<exists>(select `v_temptable`.`e` from `test`.`t3` left join `test`.`v_temptable` on((`v_temptable`.`e` = `test`.`t3`.`c`)) where ((`test`.`t3`.`c` <> `test`.`t2`.`b`) and ((<cache>(`test`.`t1`.`a`) = `v_temptable`.`e`) or isnull(`v_temptable`.`e`))) having <is_not_null_test>(`v_temptable`.`e`)))))) and (`test`.`t1`.`a` < `test`.`t2`.`b`))
EXPLAIN EXTENDED SELECT * FROM t1, t2 WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN v_merge ON (c = e) WHERE c <> b ) AND a < b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 1 PRIMARY t1 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) 2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3100.00 Using where 2 DEPENDENT SUBQUERY tv ALL NULL NULL NULL NULL 2100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1276 Field or reference 'test.t2.b' of SELECT #2 was resolved in SELECT #1 Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t1` join `test`.`t2` where ((not(<expr_cache><`test`.`t1`.`a`,`test`.`t2`.`b`>(<in_optimizer>(`test`.`t1`.`a`,<exists>(select `test`.`tv`.`e` from `test`.`t3` left join (`test`.`tv`) on((`test`.`tv`.`e` = `test`.`t3`.`c`)) where ((`test`.`t3`.`c` <> `test`.`t2`.`b`) and (<cache>(`test`.`t1`.`a`) = `test`.`tv`.`e`))))))) and (`test`.`t1`.`a` < `test`.`t2`.`b`))
Gliffy Diagrams
Attachments
Issue Links
- relates to
-
MDEV-3876 Wrong result (extra rows) with ALL subquery from a MERGE view
-
- Closed
-
Activity
- All
- Comments
- Work Log
- History
- Activity
- Transitions
just for note, derived works also incorrectly:
SELECT * FROM t1, t2
WHERE a NOT IN ( SELECT e FROM t3 LEFT JOIN (SELECT * FROM tv) as derived ON (c = e) WHERE c <> b ) AND a < b;
a b
0 1
0 2
Commited for review.
Pushed fix for 5.5.
Fixed in 5.5 (typo & test suite)
only 10.0 left waiting to merge
While the problem is not related to the change introduced in
MDEV-3862, but it's going to affect testing, so it would be good to get it fixed.