Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.0(EOL), 10.1(EOL)
Description
SET timestamp=UNIX_TIMESTAMP('2015-09-11 20:20:20');
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DROP TABLE IF EXISTS t1;
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CREATE TABLE t1 (a TIME);
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INSERT INTO t1 VALUES('10:20:30'),('00:00:00');
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SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00');
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SELECT * FROM t1 WHERE COALESCE(a)=DATE('2015-09-11');
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SELECT * FROM t1 WHERE COALESCE(a)=TIME('00:00:00') AND COALESCE(a)=DATE('2015-09-11');
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The first and the second SELECT query correctly return one row:
+----------+
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| a |
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+----------+
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| 00:00:00 |
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+----------+
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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');
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returns:
+------+-------------+-------+------+---------------+------+---------+------+------+------------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
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+------+-------------+-------+------+---------------+------+---------+------+------+------------------+
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| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible WHERE |
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+------+-------------+-------+------+---------------+------+---------+------+------+------------------+
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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';
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it returns the correct row:
+----------+
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| a |
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+----------+
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| 00:00:00 |
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+----------+
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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';
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SHOW WARNINGS;
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+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
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| Level | Code | Message |
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+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
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| 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')) |
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+-------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
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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');
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SELECT * FROM t1 WHERE COALESCE(a)=TIME'00:00:00' AND COALESCE(a)=DATE'2015-09-11';
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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
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- Closed
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