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  1. MariaDB Server
  2. MDEV-3621

LP:849763 - Wrong result with second execution of prepared statement with semijoin + view

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Fixed
    • None
    • None
    • None

    Description

      The following query:
      SELECT * FROM t2 WHERE a = SOME (
      SELECT a FROM v1 WHERE v1.c = t2.c
      );

      returns a no rows on its second execution as a prepared statement with semijoin.

      explain:

      id select_type table type possible_keys key key_len ref rows Extra
      1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using where; Start temporary
      1 PRIMARY t1 ALL NULL NULL NULL NULL 1 Using where; End temporary; Using join buffer (flat, BNL join)

      correct result:

      EXECUTE st1;
      a b c
      1 r r

      minimal optimizer switch: semijoin=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=off,derived_merge=off,derived_with_keys=off,firstmatch=off,loosescan=off,materialization=off,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=off,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: 2011-09-10 18:01:27 +0300
      build-date: 2011-09-14 10:54:25 +0300
      revno: 3183
      branch-nick: maria-5.3

      test case:

      --source include/have_innodb.inc
      SET SESSION optimizer_switch='semijoin=on';

      CREATE TABLE t1 ( c varchar(1)) engine=innodb;
      INSERT INTO t1 VALUES ('r');

      CREATE TABLE t2 ( a integer, b varchar(1), c varchar(1)) engine=innodb;
      INSERT INTO t2 VALUES (1,'r','r');

      CREATE OR REPLACE VIEW v1 AS SELECT * FROM t1;

      PREPARE st1 FROM '
      SELECT * FROM t2 WHERE a = SOME (
      SELECT a FROM v1 WHERE v1.c = t2.c
      )
      ';
      EXECUTE st1;
      EXECUTE st1;

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            psergei Sergei Petrunia
            philipstoev Philip Stoev (Inactive)
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              Created:
              Updated:
              Resolved:

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