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  1. MariaDB Server
  2. MDEV-2552

LP:870046 - Wrong result with index_condition_pushdown + GROUP BY/ORDER BY

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Details

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

    Description

      This query:

      SELECT a, MIN(d)
      FROM t1
      WHERE c = 'x'
      AND d > 'x'
      GROUP BY a;

      when executed with ICP, returns rows that do not match the second, nonindexed part, of the WHERE predicate:

      ------------+

      a MIN(d)

      ------------+

      2 x
      5 x

      ------------+

      explain:

      ----------------------------------------------------------------------------------------------------------------------------+

      id select_type table type possible_keys key key_len ref rows Extra

      ----------------------------------------------------------------------------------------------------------------------------+

      1 SIMPLE t1 ref c c 4 const 1 Using index condition; Using where; Using temporary; Using filesort

      ----------------------------------------------------------------------------------------------------------------------------+

      bzr version-info
      revision-id: <email address hidden>
      date: 2011-10-06 01:21:15 +0400
      build-date: 2011-10-07 17:34:34 +0300
      revno: 3213

      minimal switch: index_condition_pushdown=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=off,firstmatch=off,loosescan=off,materialization=off,in_to_exists=on,semijoin=off,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
      join_cache_level = 1

      test case:

      DROP TABLE t1;
      CREATE TABLE t1 ( a int, c varchar(1), d varchar(1), KEY c (c));
      INSERT INTO t1 VALUES (2,'x','x'),(5,'x','x');

      SET SESSION optimizer_switch='index_condition_pushdown=on';
      SELECT a, MIN(d)
      FROM t1
      WHERE c = 'x'
      AND d > 'x'
      GROUP BY a;

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            igor Igor Babaev
            philipstoev Philip Stoev (Inactive)
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            Dates

              Created:
              Updated:
              Resolved:

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