MySQL 是否支持分区功能查询

MySQL在5.1以后才支持分区功能，但查询是否支持分区的方法不同。

MySQL5.1中使用：

SHOW VARIABLES LIKE '%partition%';

显示结果为：

+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| have_partition_engine | YES   |
+-----------------------+-------+

表示支持分区表。

MySQL5.6中使用：SHOW PLUGINS; 来查询。

SHOW PLUGINS;

显示结果为：

+------------+----------+----------------+---------+---------+
| Name       | Status   | Type           | Library | License |
+------------+----------+----------------+---------+---------+
| binlog     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| partition  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| ARCHIVE    | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| BLACKHOLE  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| CSV        | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| FEDERATED  | DISABLED | STORAGE ENGINE | NULL    | GPL     |
| MEMORY     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| InnoDB     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| MRG_MYISAM | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| MyISAM     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| ndbcluster | DISABLED | STORAGE ENGINE | NULL    | GPL     |
+------------+----------+----------------+---------+---------+
11 rows in set (0.00 sec)

partion状态为ACTIVE表示支持分区。
或者用一条查询语句来检查INFORMATION_SCHEMA.PLUGINS 表：

SELECT 	PLUGIN_NAME as Name,
PLUGIN_VERSION as Version,
PLUGIN_STATUS as Status
FROM INFORMATION_SCHEMA.PLUGINS
WHERE PLUGIN_TYPE='STORAGE ENGINE';

如果显示结果为

+--------------------+---------+--------+
| Name               | Version | Status |
+--------------------+---------+--------+
| binlog             | 1.0     | ACTIVE |
| CSV                | 1.0     | ACTIVE |
| MEMORY             | 1.0     | ACTIVE |
| MRG_MYISAM         | 1.0     | ACTIVE |
| MyISAM             | 1.0     | ACTIVE |
| PERFORMANCE_SCHEMA | 0.1     | ACTIVE |
| BLACKHOLE          | 1.0     | ACTIVE |
| ARCHIVE            | 3.0     | ACTIVE |
| InnoDB             | 5.6     | ACTIVE |
| partition          | 1.0     | ACTIVE |
+--------------------+---------+--------+
10 rows in set (0.00 sec)

partion为ACTIVE表示支持分区。

MySQL查看和新增表分区
1、查看表分区

SELECT
partition_name part,
partition_expression expr,
partition_description descr,
FROM_DAYS(partition_description) lessthan_sendtime,
table_rows
FROM
INFORMATION_SCHEMA.partitions
WHERE
TABLE_SCHEMA = SCHEMA()
AND TABLE_NAME='td_sendmessagelog'; ---这里是表名

2、添加表分区

ALTER TABLE td_sendmessagelog ADD PARTITION (
PARTITION p20150210 VALUES LESS THAN (TO_DAYS('2015-02-10')),
PARTITION p20150220 VALUES LESS THAN (TO_DAYS('2015-02-20')),
PARTITION p20150301 VALUES LESS THAN (TO_DAYS('2015-03-01')),
PARTITION p20150310 VALUES LESS THAN (TO_DAYS('2015-03-10')),
PARTITION p20150320 VALUES LESS THAN (TO_DAYS('2015-03-20')),
PARTITION p20150401 VALUES LESS THAN (TO_DAYS('2015-04-01')),
PARTITION p20150410 VALUES LESS THAN (TO_DAYS('2015-04-10')),
PARTITION p20150420 VALUES LESS THAN (TO_DAYS('2015-04-20')),
PARTITION p20150501 VALUES LESS THAN (TO_DAYS('2015-05-01')),
PARTITION pmax VALUES LESS THAN (maxvalue)
);

注意：创建表分区，要指定对应的列。上面例子，用的是一个时间列（sendtime）
创建表过程如下（注意指定的primary key）：

create table td_sendmessagelog
(
id                   int not null,
sendtime                 datetime not null
primary key (id,sendtime)
)
创建索引：
create index Index_sid_sendtime on td_sendmessagelog
(
sid,
sendtime
);