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  1. MariaDB Server
  2. MDEV-8694

Wrong result for SELECT..WHERE a NOT LIKE 'a ' AND a='a'

    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 10.1.6, 5.5, 10.0
    • Fix Version/s: 10.1.7
    • Component/s: Optimizer
    • Labels:
      None

      Description

      This script:

      DROP TABLE IF EXISTS t1;
      CREATE TABLE t1 (a VARCHAR(10) COLLATE latin1_bin);
      INSERT INTO t1 VALUES ('a'),('a ');
      SELECT a, LENGTH(a) FROM t1 WHERE a NOT LIKE 'a ';

      returns one row:

      +------+-----------+
      | a    | LENGTH(a) |
      +------+-----------+
      | a    |         1 |
      +------+-----------+

      Now if I make the condition even stronger:

      SELECT a, LENGTH(a) FROM t1 WHERE a NOT LIKE 'a ' AND a='a';

      it erroneously returns 2 rows:

      +------+-----------+
      | a    | LENGTH(a) |
      +------+-----------+
      | a    |         1 |
      | a    |         2 |
      +------+-----------+

      The problem happens in equal fields propagation.

      WHERE a NOT LIKE 'a ' AND a='a'

      gets rewritten to

      WHERE 'a' NOT LIKE 'a ' AND a='a'

      then LIKE gets removed from the condition.

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              • Assignee:
                bar Alexander Barkov
                Reporter:
                bar Alexander Barkov
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                Dates

                • Created:
                  Updated:
                  Resolved: