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  1. MariaDB Server
  2. MDEV-28858

Wrong result with table elimination combined with not_null_range_scan

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      Description

      The following tests shows we get different results depending on the setting of
      'not_null_range_scan':

      CREATE TABLE t1 (a INT, b INT) ENGINE=MyISAM;
      INSERT INTO t1 VALUES (10,1),(null,2);
      CREATE TABLE t2 (pk INT PRIMARY KEY) ENGINE=MyISAM;
      INSERT INTO t2 VALUES (1),(2);
      SET optimizer_switch= 'not_null_range_scan=on';
      SELECT t1.b FROM t1 LEFT JOIN t2 ON t1.a = t2.pk WHERE t1.a IS NULL ORDER BY t1.b;
      SET optimizer_switch= 'not_null_range_scan=off';
      SELECT t1.b FROM t1 LEFT JOIN t2 ON t1.a = t2.pk WHERE t1.a IS NULL ORDER BY t1.b;

      The first test returns 0 rows and the second test 1 row.

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            Assignee:
            monty Michael Widenius
            Reporter:
            monty Michael Widenius
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              Created:
              Updated:
              Resolved:

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