关于分区表，函数YEARWEEK无效的疑问。
DROP TABLE IF EXISTS `part_test`;CREATE TABLE `part_test` ( `id` mediumint(9) NOT NULL AUTO_INCREMENT, `date` date NOT NULL, PRIMARY KEY (`id`,`date`)) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=5 ;-- -- 导出表中的数据 `part_test`-- INSERT INTO `part_test` (`id`, `date`) VALUES (3, '2012-01-03'),(4, '2012-01-22');--分区ALTER TABLE `part_test` PARTITION BY RANGE(yearweek(date)) ( PARTITION p201201 VALUES LESS THAN (201202), PARTITION p201202 VALUES LESS THAN (201203), PARTITION p201203 VALUES LESS THAN (201204), PARTITION p201204 VALUES LESS THAN (201205));//下边应该是属于今年的第三个星期的也就是等于201203 ,预计查询不会访问第一分区(p201201)才对，但是执行结果是扫描了不该扫描的第一个分区mysql> explain partitions SELECT count(*) FROM `part_test` WHERE `date` > '2012-01-08';+----+-------------+-----------+---------------------------------+-------+---------------+---------+---------+------+------+--------------------------+| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |+----+-------------+-----------+---------------------------------+-------+---------------+---------+---------+------+------+--------------------------+| 1 | SIMPLE | part_test | p201201,p201202,p201203,p201204 | index | NULL | PRIMARY | 6 | NULL | 2 | Using where; Using index |+----+-------------+-----------+---------------------------------+-------+---------------+---------+---------+------+------+--------------------------+1 row in set (0.00 sec)
DROP TABLE IF EXISTS `part_test`;CREATE TABLE `part_test` ( `id` mediumint(9) NOT NULL AUTO_INCREMENT, `date` date NOT NULL, PRIMARY KEY (`id`,`date`)) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=5 ;-- -- 导出表中的数据 `part_test`-- INSERT INTO `part_test` (`id`, `date`) VALUES (3, '2012-01-03'),(4, '2012-01-22');ALTER TABLE `part_test` PARTITION BY RANGE(to_days(date)) ( PARTITION p201201 VALUES LESS THAN (to_days('2012-01-08')), PARTITION p201202 VALUES LESS THAN (to_days('2012-01-15')), PARTITION p201203 VALUES LESS THAN (to_days('2012-01-23')), PARTITION p201204 VALUES LESS THAN (to_days('2012-01-30')));//下边应该是属于今年的第三个星期的也就是等于201203 ,符合预期mysql> explain partitions SELECT count(*) FROM `part_test` WHERE `date` > '2012-01-16';+----+-------------+-----------+-----------------+--------+---------------+------+---------+------+------+-------+| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | Extra |+----+-------------+-----------+-----------------+--------+---------------+------+---------+------+------+-------+| 1 | SIMPLE | part_test | p201203,p201204 | system | NULL | NULL | NULL | NULL | 1 | |+----+-------------+-----------+-----------------+--------+---------------+------+---------+------+------+-------+1 row in set (0.00 sec)mysql> \s--------------mysql Ver 14.14 Distrib 5.1.28-rc, for Win32 (ia32)