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  1. MariaDB Server
  2. MDEV-5161

Wrong result (missing rows) with semijoin, LEFT JOIN, ORDER BY, constant table

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 10.0.4, 5.3.12, 5.5.33a
    • Fix Version/s: 5.5.35, 10.0.7
    • Component/s: None
    • Labels:
      None

      Description

      The test case is nearly identical to the one provided in the comment to MDEV-5059 (https://mariadb.atlassian.net/browse/MDEV-5059?focusedCommentId=35418&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-35418); the only difference is that table t3 lost the index, and the wrong result now affects the default join_cache_level=2.

      Test case:

      SET optimizer_switch = 'semijoin=on';
       
      CREATE TABLE t1 (pk INT PRIMARY KEY, c1 VARCHAR(1)) ENGINE=MyISAM;
      INSERT INTO t1 VALUES (1,'v'),(2,'v'),(3,'c'),(4,NULL),(5,'x');
       
      CREATE TABLE t2 (c2 VARCHAR(1)) ENGINE=MyISAM;
      INSERT INTO t2 VALUES ('x');
       
      CREATE TABLE t3 (c3 VARCHAR(1)) ENGINE=MyISAM;
      INSERT INTO t3 VALUES ('x'),('d');
       
      SELECT * FROM t1, t2 WHERE pk IN ( SELECT pk FROM t1 LEFT JOIN t3 ON (c1 = c3 ) ) ORDER BY c2, c1;

      Actual result:

      pk	c1	c2
      4	NULL	x

      Expected result:

      pk	c1	c2
      4	NULL	x
      3	c	x
      1	v	x
      2	v	x
      5	x	x

      revision-id: bar@mnogosearch.org-20131016141313-63jt6geakz1e6dg2
      revno: 3708
      branch-nick: 5.3

      EXPLAIN EXTENDED
      SELECT * FROM t1, t2 WHERE pk IN ( SELECT pk FROM t1 LEFT JOIN t3 ON (c1 = c3 ) ) ORDER BY c2, c1;
      id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
      1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	100.00	Using filesort
      1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	5	100.00	
      1	PRIMARY	t1	eq_ref	PRIMARY	PRIMARY	4	test.t1.pk	1	100.00	
      1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Start temporary; End temporary
      Warnings:
      Note	1003	select `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`c1` AS `c1`,'x' AS `c2` from `test`.`t1` semi join (`test`.`t3`) join `test`.`t1` join `test`.`t2` where (`test`.`t1`.`pk` = `test`.`t1`.`pk`) order by 'x',`test`.`t1`.`c1`

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              Assignee:
              psergey Sergei Petrunia
              Reporter:
              elenst Elena Stepanova
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                Dates

                Created:
                Updated:
                Resolved: