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  1. MariaDB Server
  2. MDEV-8741

Equal field propagation leaves some remainders after simplifying WHERE zerofill_column=2010 AND zerofill_column>=2010

Details

    Description

      This script:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a INT ZEROFILL);
      		 
      INSERT INTO t1 VALUES (2010),(2020);
      		 
      EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
      		 
      SHOW WARNINGS;

      returns

      +-------+------+---------------------------------------------------------------------------------------+
      		 
      | Level | Code | Message                                                                               |
      		 
      +-------+------+---------------------------------------------------------------------------------------+
      		 
      | Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and 1) |
      		 
      +-------+------+---------------------------------------------------------------------------------------+

      Notice, the a>=2010 part was simplified to constant, but the constant was not removed.

      The same problems is repeatable with the YEAR data type:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a YEAR);
      		 
      INSERT INTO t1 VALUES (2010),(2020);
      		 
      EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
      		 
      SHOW WARNINGS;

      If I use "INT" instead of "INT ZEROFILL" or "YEAR", it works as expected:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a INT);
      		 
      INSERT INTO t1 VALUES (2010),(2020);
      		 
      EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
      		 
      SHOW WARNINGS;

      returns:

      +-------+------+-------------------------------------------------------------------------------+
      		 
      | Level | Code | Message                                                                       |
      		 
      +-------+------+-------------------------------------------------------------------------------+
      		 
      | Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where (`test`.`t1`.`a` = 2010) |
      		 
      +-------+------+-------------------------------------------------------------------------------+

      as expected.

      Attachments

        Issue Links

          blocks

          Bug - A problem which impairs or prevents the functions of the product. MDEV-8728 Fix a number of problems in equal field and equal expression propagation

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

          Activity

            Ascending order - Click to sort in descending order
            bar Alexander Barkov created issue -
            bar Alexander Barkov made changes -
            Field Original Value New Value
            bar Alexander Barkov made changes -
            Fix Version/s 10.1.7 [ 19604 ]
            Fix Version/s 10.1 [ 16100 ]
            Resolution Fixed [ 1 ]
            Status Open [ 1 ] Closed [ 6 ]
            bar Alexander Barkov made changes -
            Labels propagation
            bar Alexander Barkov added a comment -

            MySQL-5.7.8 does not seem to remove the constant part (the result of propagation) from the WHERE condition:

            DROP TABLE IF EXISTS t1;
            		 
            CREATE TABLE t1 (a INT ZEROFILL);
            		 
            INSERT INTO t1 VALUES (2010),(2020);
            		 
            EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010;
            		 
            SHOW WARNINGS;

            returns

            +---------+------+-------------------------------------------------------------------------------------------------------------------+
            		 
            | Level   | Code | Message                                                                                                           |
            		 
            +---------+------+-------------------------------------------------------------------------------------------------------------------+
            		 
            | Warning | 1681 | 'EXTENDED' is deprecated and will be removed in a future release.                                                 |
            		 
            | Note    | 1003 | /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and (2010 >= 2010)) |
            		 
            +---------+------+-------------------------------------------------------------------------------------------------------------------

            bar Alexander Barkov added a comment - MySQL-5.7.8 does not seem to remove the constant part (the result of propagation) from the WHERE condition: DROP TABLE IF EXISTS t1; CREATE TABLE t1 (a INT ZEROFILL); INSERT INTO t1 VALUES (2010),(2020); EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=2010 AND a>=2010; SHOW WARNINGS; returns +---------+------+-------------------------------------------------------------------------------------------------------------------+ | Level | Code | Message | +---------+------+-------------------------------------------------------------------------------------------------------------------+ | Warning | 1681 | 'EXTENDED' is deprecated and will be removed in a future release. | | Note | 1003 | /* select#1 */ select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` = 2010) and (2010 >= 2010)) | +---------+------+-------------------------------------------------------------------------------------------------------------------
            bar Alexander Barkov made changes -
            Labels propagation propagation upstream
            serg Sergei Golubchik made changes -
            Workflow MariaDB v3 [ 71346 ] MariaDB v4 [ 149564 ]

            People

              bar Alexander Barkov
              bar Alexander Barkov
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              Dates

                Created:
                Updated:
                Resolved:

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