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  1. MariaDB Server
  2. MDEV-34600

Wrong unusable key column on char_col BETWEEN 'a' AND 3

Details

    • Bug
    • Status: Open (View Workflow)
    • Major
    • Resolution: Unresolved
    • 10.6, 11.6(EOL)
    • 10.6
    • Data types, Optimizer
    • None

    Description

      SET @@note_verbosity='all';
      		 
      CREATE OR REPLACE TABLE t1 (f char(8), KEY(f));
      		 
      INSERT INTO t1 VALUES (''),('');
      		 
      SELECT * FROM t1 WHERE f BETWEEN 'a' AND 3;
      		 
      SHOW WARNINGS;


      +---------+------+----------------------------------------------------------------------------------------------------------------------------+
      		 
      | Level   | Code | Message                                                                                                                    |
      		 
      +---------+------+----------------------------------------------------------------------------------------------------------------------------+
      		 
      | Note    | 1105 | Cannot use key `f` part[0] for lookup: `test`.`t1`.`f` of collation `utf8mb4_uca1400_ai_ci` >= "'a'" of collation `binary` |
      		 
      | Warning | 1292 | Truncated incorrect DECIMAL value: ''                                                                                      |
      		 
      | Warning | 1292 | Truncated incorrect DECIMAL value: 'a'                                                                                     |
      		 
      | Warning | 1292 | Truncated incorrect DECIMAL value: ''                                                                                      |
      		 
      | Warning | 1292 | Truncated incorrect DECIMAL value: 'a'                                                                                     |
      		 
      +---------+------+----------------------------------------------------------------------------------------------------------------------------+

      Notice, the warning about the unusable key is incorrect. It should report a wrong data type instead, because the comparison is done using the DECIMAL data type.

      If I change the order of the BETNEEN values, it correctly reports the data type problem:

      SELECT * FROM t1 WHERE f BETWEEN 3  AND 'a';
      		 
      SHOW WARNINGS;


      +---------+------+--------------------------------------------------------------------------------------------+
      		 
      | Level   | Code | Message                                                                                    |
      		 
      +---------+------+--------------------------------------------------------------------------------------------+
      		 
      | Note    | 1105 | Cannot use key `f` part[0] for lookup: `test`.`t1`.`f` of type `char` >= "3" of type `int` |
      		 
      | Warning | 1292 | Truncated incorrect DOUBLE value: ''                                                       |
      		 
      | Warning | 1292 | Truncated incorrect DOUBLE value: 'a'                                                      |
      		 
      | Warning | 1292 | Truncated incorrect DOUBLE value: ''                                                       |
      		 
      | Warning | 1292 | Truncated incorrect DOUBLE value: 'a'                                                      |
      		 
      +---------+------+--------------------------------------------------------------------------------------------+

      Attachments

        Issue Links

          relates to

          Task - A task that needs to be done. MDEV-32203 Raise notes when an index cannot be used on data type mismatch

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-32957 Unusable key notes report wrong predicates for > and >=

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-32958 Unusable key notes do not get reported for some operations

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-34601 Unusable key notes do not get reported for IN on data types mismatch

          • Major - Major loss of function.
          • Open

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              bar Alexander Barkov
              bar Alexander Barkov
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              Dates

                Created:
                Updated:

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