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  1. MariaDB Server
  2. MDEV-10305

CAST(string_expr AS SIGNED) does not truncate huge numbers well

Details

    • Bug
    • Status: Open (View Workflow)
    • Minor
    • Resolution: Unresolved
    • 10.0(EOL), 10.1(EOL), 10.2(EOL)
    • 10.2(EOL)
    • OTHER
    • None

    Description

      Implicit CAST from string to signed bigint truncates the number the to maximum possible 64-bit signed value:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a BIGINT);
      		 
      INSERT INTO t1 VALUES ('99999999999999999999');
      		 
      SELECT * FROM t1;


      +---------------------+
      		 
      | a                   |
      		 
      +---------------------+
      		 
      | 9223372036854775807 |
      		 
      +---------------------+

      So does explicit CAST from DECIMAL to SIGNED:

      SELECT CAST(99999999999999999999 AS SIGNED);


      +--------------------------------------+
      		 
      | CAST(99999999999999999999 AS SIGNED) |
      		 
      +--------------------------------------+
      		 
      |                  9223372036854775807 |
      		 
      +--------------------------------------+

      So does explicit CAST from DOUBLE to SIGNED:

      SELECT CAST(99999999999999999999e0 AS SIGNED);


      +----------------------------------------+
      		 
      | CAST(99999999999999999999e0 AS SIGNED) |
      		 
      +----------------------------------------+
      		 
      |                    9223372036854775807 |
      		 
      +----------------------------------------+

      Explicit CAST from string to SIGNED works differently:

      SELECT CAST('99999999999999999999' AS SIGNED);


      +----------------------------------------+
      		 
      | CAST('99999999999999999999' AS SIGNED) |
      		 
      +----------------------------------------+
      		 
      |                                     -1 |
      		 
      +----------------------------------------+

      This looks wrong. Explicit CAST from string to SIGNED should also return 9223372036854775807.

      Attachments

        Activity

          bar Alexander Barkov added a comment -

          Dynamic columns also do not work well:

          SELECT COLUMN_GET(COLUMN_CREATE(0,'99999999999999999999'), 0 AS SIGNED);


          +------------------------------------------------------------------+
          		 
          | COLUMN_GET(COLUMN_CREATE(0,'99999999999999999999'), 0 AS SIGNED) |
          		 
          +------------------------------------------------------------------+
          		 
          |                                                               -1 |
          		 
          +------------------------------------------------------------------+

          bar Alexander Barkov added a comment - Dynamic columns also do not work well: SELECT COLUMN_GET(COLUMN_CREATE(0, '99999999999999999999' ), 0 AS SIGNED); +------------------------------------------------------------------+ | COLUMN_GET(COLUMN_CREATE(0,'99999999999999999999'), 0 AS SIGNED) | +------------------------------------------------------------------+ | -1 | +------------------------------------------------------------------+

          People

            bar Alexander Barkov
            bar Alexander Barkov
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            Dates

              Created:
              Updated:

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