当然，还有FLOOR（），CEILING() 等，前提是使用这两个分区函数的分区健必须是整型。
要小心使用其中的一些函数，避免犯逻辑性的错误，引起全表扫描。
比如：
create table ptime11(id int,createdate datetime) engine=myisam partition by range (day(createdate)) (partition po values less than (15),partition p1 values less than (31)); mysql> insert into ptime11 values (1,'2010-06-17'); mysql> explain partitions select count(1) from ptime11 where createdate>'2010-08-17'\G; *************************** 1. row *************************** id: 1 select_type: SIMPLE table: ptime11 partitions: po,p1 type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 5 Extra: Using where 1 row in set (0.00 sec) |
8.主键及约束测试
分区健不包含在主键内
mysql> create table pprimary(id int,createdate datetime,primary key(id)) engine=myisam partition by range (day(createdate)) (partition po values less than (15),partition p1 values less than (31)); www.2cto.com
ERROR 1503 (HY000): A PRIMARY KEY must include all columns in the table's partitioning function
分区健包含在主键内
mysql> create table pprimary1(id int,createdate datetime,primary key(id,createdate)) engine=myisam partition by range (day(createdate)) (partition po values less than (15),partition p1 values less than (31));
Query OK, 0 rows affected (0.05 sec)
说明分区健必须包含在主键里面。
mysql> create table pprimary2(id int,createdate datetime,uid char(10),primary key(id,createdate),unique key(uid)) engine=myisam partition by range(to_days(createdate))(partition p0 values less than (20100801),partition p1 values less than (20100901));
ERROR 1503 (HY000): A UNIQUE INDEX must include all columns in the table's partitioning function
说明在表上建约束索引会有问题，必须把约束索引列包含在分区健内。
mysql> create table pprimary3(id int,createdate datetime,uid char(10),primary key(id,createdate),unique key(createdate)) engine=myisam partition by range(to_days(createdate))(partition p0 values less than (20100801),partition p1 values less than (20100901));
Query OK, 0 rows affected (0.00 sec)
虽然在表上可以加约束索引，但是只有包含在分区健内，这种情况在实际应用过程中会遇到问题，这个问题点在以后的MYSQL 版本中也许会改进。
9.子分区测试
只有RANGE和LIST分区才能有子分区，每个分区的子分区数量必须相同，
mysql> create table pprimary7(id int,createdate datetime,uid char(10),primary key(id,createdate)) engine=myisam partition by range(to_days(createdate)) subpartition by hash(to_days(createdate))(partition p0 values less than (20100801) ( subpartition so,subpartition s1) ,partition p1 values less than (20100901) (subpartition s0,subpartition s1)); www.2cto.com
ERROR 1517 (HY000): Duplicate partition name s1
提示了重复的分区名称错误，这和MYSQL5.1帮助文档中的说明有出入，不知道是不是这个问题在某个小版本中修改过。
10.MYSQL分区健NULL值测试；
MYSQL将NULL值视为0.自动插入最小的分区中。
11.MYSQL分区管理测试
mysql> alter table pprimary4 truncate partition p1;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'truncate partition p1' at line 1
5.1版本中还不支持这个语法，5.5中已经支持，很好的一个命令；
ALTER TABLE reorganize 可以重新组织分区。
