查看表的分布状况mysql> select count(*) from  justin;+----------+| count(*) |+----------+|  5845246 |+----------+1 row in set (0.00 sec)

mysql> select month(create_time),count(*) from justin group by  month(create_time);+-----------------------+----------+| month(create_time) | count(*) |+-----------------------+----------+|                     1 |  1128520 ||                    11 |  1574965 ||                    12 |  3141750 |+-----------------------+----------+3 rows in set (6.93 sec)

考虑以create_time为分区键建立分区表

第一步  创建中间表，以主键id和分区列为联合主键CREATE TABLE `temp_justin` (  `id` bigint(1) NOT NULL AUTO_INCREMENT COMMENT '流水号,自增',  `create_time` datetime DEFAULT NULL COMMENT '订单日志创建时间(建立索引)',  PRIMARY KEY (`id`,`create_time`),) ENGINE=MyISAM AUTO_INCREMENT=6000000 DEFAULT CHARSET=utf8;表已经存在580多万记录并且不断在增长，因此中间表初始的id值设置成6000000

增加分区，以月为单位alter table temp_justin partition by range(to_days(create_time))( partition p1012 values less than (to_days('2011-01-01')),partition p1101 values less than (to_days('2011-02-01')),partition p1102 values less than (to_days('2011-03-01')),partition p1103 values less than (to_days('2011-04-01')),partition p1104 values less than (to_days('2011-05-01')),partition p1105 values less than (to_days('2011-06-01')),partition p1106 values less than (to_days('2011-07-01')),partition p1107 values less than (to_days('2011-08-01')),partition p1108 values less than (to_days('2011-09-01')),partition p1109 values less than (to_days('2011-10-01')),partition p11010 values less than (to_days('2011-11-01')),partition p11011 values less than (to_days('2011-12-01')),partition p11012 values less than (to_days('2012-01-01')));

第二步 重命名表Alter table justin rename to justin_bak_110113;Alter table temp_justin rename to justin;

第三步 同步数据Insert into justin select * from temp_justin;表里已经存在将近600万条记录，如此批量导入数据会对数据库性能影响很大。

每一万条提交一次，sleep 2s ，53万数据总耗时2 min 39.67 sec。mysql> create procedure cp_data()    -> begin    -> declare i int;    -> set i=0;    -> while i insert into justin     -> select * from justin_bak_110113     -> where id >= i*10000 and  id set i=i+1;    -> select sleep(2);    -> end while;    -> end||Query OK, 0 rows affected (0.04 sec)

mysql> mysql> delete from justin;    -> ||Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;mysql> call cp_data();

+----------+| sleep(2) |+----------+|        0 |+----------+1 row in set (2 min 39.67 sec)

Query OK, 0 rows affected (2 min 39.67 sec)

mysql> select count(*) from justin;+----------+| count(*) |+----------+|   525031 |+----------+1 row in set (0.00 sec)

查看执行计划，使用了分区扫描mysql> explain     -> select count(*) from justin where create_time    -> '2011-01-04';+----+-------------+--------------------+-------+---------------+---------+---------+------+--------+--------------------------+| id | select_type | table              | type  | possible_keys | key     | key_len | ref  | rows   | Extra                    |+----+-------------+--------------------+-------+---------------+---------+---------+------+--------+--------------------------+|  1 | SIMPLE      | justin | index | NULL          | PRIMARY | 16      | NULL | 525031 | Using where; Using index |+----+-------------+--------------------+-------+---------------+---------+---------+------+--------+--------------------------+1 row in set (0.00 sec)

mysql> explain    -> partitions    -> select count(*) from justin where create_time    -> '2011-01-04';+----+-------------+--------------------+-------------+-------+---------------+---------+---------+------+--------+--------------------------+| id | select_type | table              | partitions  | type  | possible_keys | key     | key_len | ref  | rows   | Extra                    |+----+-------------+--------------------+-------------+-------+---------------+---------+---------+------+--------+--------------------------+|  1 | SIMPLE      | justin | p1012,p1101 | index | NULL          | PRIMARY | 16      | NULL | 525031 | Using where; Using index |+----+-------------+--------------------+-------------+-------+---------------+---------+---------+------+--------+--------------------------+1 row in set (0.00 sec)