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  1. MariaDB Server
  2. MDEV-10306

Wrong results with combination of CONCAT, SUBSTR and CONVERT in subquery

    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 5.3.12, 5.5.48, 10.0.24, 10.1.11
    • Fix Version/s: 10.0.32
    • Component/s: Optimizer
    • Labels:
      None
    • Environment:
      Linux
    • Sprint:
      10.0.30

      Description

      There seems to be a problem with the combination of CONCAT, SUBSTR and CONVERT in subquery. Simplest test case so far that reproduces this is:

      DROP TABLE IF EXISTS t1;
      CREATE TABLE t1 (t VARCHAR(10) CHARSET latin1);
       
      INSERT INTO t1 VALUES('1234567');
       
      SELECT CONCAT(SUBSTR(t2, 1, 3), SUBSTR(t2, 5)) c1
                  , CONCAT(SUBSTR(t2,1,3),'---',SUBSTR(t2,5)) c2
         FROM (SELECT CONVERT(t USING latin1) t2 FROM t1) sub;
      

      Expected result, produced by MariaDB 5.1.x and 5.2.x, and all tested versions of MySQL:

      +--------+-----------+
      | c1     | c2        |
      +--------+-----------+
      | 123567 | 123---567 |
      +--------+-----------+
      

      MariaDB 5.3.x result:

      +--------+-----------+
      | c1     | c2        |
      +--------+-----------+
      | 123567 | 123456567 |
      +--------+-----------+
      

      MariaDB 5.5.x - 10.1.x:

      +--------+-----------+
      | c1     | c2        |
      +--------+-----------+
      | 12356  | 123456567 |
      +--------+-----------+
      

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              • Assignee:
                bar Alexander Barkov
                Reporter:
                hholzgra Hartmut Holzgraefe
              • Votes:
                1 Vote for this issue
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                Dates

                • Created:
                  Updated:
                  Resolved: