[MDEV-11333] Expect "Impossible where condition" for WHERE timestamp_field>=DATE_ADD(TIMESTAMP'9999-01-01 00:00:00',INTERVAL 1000 YEAR) - Jira

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This query returns NULL with a warning about datetime overflow.

SELECT DATE_ADD(TIMESTAMP'9999-01-01 00:00:00',INTERVAL 1000 YEAR);

If I use now this expression in a WHERE condition on a TIMESTAMP field with DEFAULT CURRENT_TIMESTAMP:

DROP TABLE IF EXISTS t1;

CREATE TABLE t1 (a TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, KEY(a)) ENGINE=MyISAM;

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

INSERT INTO t1 VALUES('2001-01-01'),('2002-02-02'),('2003-03-03');

EXPLAIN SELECT * FROM t1 WHERE a >= DATE_ADD(TIMESTAMP'9999-01-01 00:00:00',INTERVAL 1000 YEAR);

it reports that one row will be checked:

+------+-------------+-------+-------+---------------+------+---------+------+------+--------------------------+

| id   | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | Extra                    |

+------+-------------+-------+-------+---------------+------+---------+------+------+--------------------------+

|    1 | SIMPLE      | t1    | range | a             | a    | 4       | NULL |    1 | Using where; Using index |

+------+-------------+-------+-------+---------------+------+---------+------+------+--------------------------+

This is wrong. It should report "Impossible where".

Note, if I change the condition wrapping DATE_ADD to COALESCE:

EXPLAIN SELECT * FROM t1 WHERE a >= COALESCE(DATE_ADD(TIMESTAMP'9999-01-01 00:00:00',INTERVAL 1000 YEAR));

it starts to report "Impossible where" correctly:

+------+-------------+-------+------+---------------+------+---------+------+------+-----------------------------------------------------+

| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | Extra                                               |

+------+-------------+-------+------+---------------+------+---------+------+------+-----------------------------------------------------+

|    1 | SIMPLE      | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL | Impossible WHERE noticed after reading const tables |

+------+-------------+-------+------+---------------+------+---------+------+------+-----------------------------------------------------+

blocks

MDEV-4912 Data type plugin API version 1

MDEV-11337 Split Item::save_in_field() into virtual methods in Type_handler

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