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  1. MariaDB Server
  2. MDEV-8793

Wrong result set for SELECT ... WHERE COALESCE(time_column)=TIME('00:00:00') AND COALESCE(time_column)=DATE('2015-09-11')

Details

    Description

      SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
      		 
      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a TIME);
      		 
      INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
      		 
      SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
      		 
      SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
      		 
      SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');

      The first and the second SELECT query correctly return one row:

      +----------+
      		 
      | a        |
      		 
      +----------+
      		 
      | 00:00:00 |
      		 
      +----------+

      The third query erroneously returns empty set.

      EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');

      returns:

      +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
      		 
      | id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra            |
      		 
      +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
      		 
      |    1 | SIMPLE      | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | Impossible WHERE |
      		 
      +------+-------------+-------+------+---------------+------+---------+------+------+------------------+

      The problem happens in Arg_comparator::datetime() called from propagate_cond_constants.
      Arg_comparator tries to compare the TIME and the DATE literals and fails.

      If I rewrite the query like this:

      SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';

      it returns the correct row:

      +----------+
      		 
      | a        |
      		 
      +----------+
      		 
      | 00:00:00 |
      		 
      +----------+

      But equal expression propagation is not performed:

      EXPLAIN EXTENDED SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';
      		 
      SHOW WARNINGS;
      		 

      +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
      		 
      | Level | Code | Message                                                                                                                                                |
      		 
      +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
      		 
      | Note  | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((coalesce(`test`.`t1`.`a`) = TIME'00:00:00') and (coalesce(`test`.`t1`.`a`) = DATE'2015-09-11')) |
      		 
      +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+

      which also looks like a bug.

      Summary: both queries:

      SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
      		 
      SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';

      are expected to return one row, and perform equal expression propagation.

      • the first query performs propagation but returns a wrong result
      • the second query returns a correct result but does not perform propagation

      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 -
            Description {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.
            		 {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.

            {code}
            EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            returns:
            {noformat}
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            {noformat}
            bar Alexander Barkov made changes -
            Description {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.

            {code}
            EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            returns:
            {noformat}
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            {noformat}
            		 {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.

            {code}
            EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            returns:
            {noformat}
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            {noformat}

            The problem happens in Arg_comparator::datetime() called from propagate_cond_constants.
            Arg_comparator tries to compare the TIME and the DATE literals and fails.
            bar Alexander Barkov made changes -
            Description {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.

            {code}
            EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            returns:
            {noformat}
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            {noformat}

            The problem happens in Arg_comparator::datetime() called from propagate_cond_constants.
            Arg_comparator tries to compare the TIME and the DATE literals and fails.
            		 {code}
            SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
            DROP TABLE IF EXISTS t1;
            CREATE TABLE t1 (a TIME);
            INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
            SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            The first and the second SELECT query correctly return one row:
            {code}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {code}
            The third query erroneously returns empty set.

            {code}
            EXPLAIN SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            {code}
            returns:
            {noformat}
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            | 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
            +------+-------------+-------+------+---------------+------+---------+------+------+------------------+
            {noformat}

            The problem happens in Arg_comparator::datetime() called from propagate_cond_constants.
            Arg_comparator tries to compare the TIME and the DATE literals and fails.

            If I rewrite the query like this:
            {code}
            SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';
            {code}
            it returns the correct row:
            {noformat}
            +----------+
            | a |
            +----------+
            | 00:00:00 |
            +----------+
            {noformat}

            But equal expression propagation is not performed:
            {code}
            EXPLAIN EXTENDED SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';
            SHOW WARNINGS;
            {code}
            {noformat}
            +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
            | Level | Code | Message |
            +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
            | Note | 1003 | select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((coalesce(`test`.`t1`.`a`) = TIME'00:00:00') and (coalesce(`test`.`t1`.`a`) = DATE'2015-09-11')) |
            +-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
            {noformat}
            which also looks like a bug.

            Summary: both queries:
            {code}
            SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';
            {code}
            are expected to return one row, and perform equal expression propagation.
            - the first query performs propagation but returns a wrong result
            - the second query returns a correct result but does not perform propagation
            bar Alexander Barkov made changes -
            Status Open [ 1 ] In Progress [ 3 ]
            bar Alexander Barkov made changes -
            Labels propagation
            bar Alexander Barkov added a comment -

            MySQL-5.7.8 does not support equal expression propagation in this example:

            EXPLAIN EXTENDED SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
            		 
            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 ((coalesce(`test`.`t1`.`a`) = TIME'00:00:00') and (coalesce(`test`.`t1`.`a`) = DATE'2015-09-11')) |
            		 
            +---------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------+

            bar Alexander Barkov added a comment - MySQL-5.7.8 does not support equal expression propagation in this example: EXPLAIN EXTENDED SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11'); 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 ((coalesce(`test`.`t1`.`a`) = TIME'00:00:00') and (coalesce(`test`.`t1`.`a`) = DATE'2015-09-11')) | +---------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------+
            bar Alexander Barkov made changes -
            Component/s Temporal Types [ 11000 ]
            Fix Version/s 10.1.8 [ 19605 ]
            Fix Version/s 10.1 [ 16100 ]
            Resolution Fixed [ 1 ]
            Status In Progress [ 3 ] Closed [ 6 ]
            serg Sergei Golubchik made changes -
            Workflow MariaDB v3 [ 71530 ] MariaDB v4 [ 149607 ]

            People

              bar Alexander Barkov
              bar Alexander Barkov
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              Dates

                Created:
                Updated:
                Resolved:

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