深入解析MySQL分区（Partition）功能(四)
VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY KEY (uid) PARTITIONS 4 (
PARTITION p0
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx',
PARTITION p2
DATA DIRECTORY = '/data4/data'
INDEX DIRECTORY = '/data5/idx',
PARTITION p3
DATA DIRECTORY = '/data6/data'
INDEX DIRECTORY = '/data7/idx'
);
分成4个区，数据文件和索引文件单独存放。
* 子分区
子分区是针对 RANGE/LIST 类型的分区表中每个分区的再次分割。再次分割可以是 HASH/KEY 等类型。例如：
[sql]
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY RANGE (uid) SUBPARTITION BY HASH (uid % 4) SUBPARTITIONS 2(
PARTITION p0 VALUES LESS THAN (3000000)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES LESS THAN (6000000)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx'
);
对 RANGE 分区再次进行子分区划分，子分区采用 HASH 类型。
或者
[sql]
CREATE TABLE users (
uid INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL DEFAULT '',
email VARCHAR(30) NOT NULL DEFAULT ''
)
PARTITION BY RANGE (uid) SUBPARTITION BY KEY(uid) SUBPARTITIONS 2(
PARTITION p0 VALUES LESS THAN (3000000)
DATA DIRECTORY = '/data0/data'
INDEX DIRECTORY = '/data1/idx',
PARTITION p1 VALUES LESS THAN (6000000)
DATA DIRECTORY = '/data2/data'
INDEX DIRECTORY = '/data3/idx'
);
对 RANGE 分区再次进行子分区划分，子分区采用 KEY 类型。
= 分区管理 =
* 删除分区
[sql]
ALERT TABLE users DROP PARTITION p0;
删除分区 p0。
* 重建分区
o RANGE 分区重建
[sql]
ALTER TABLE users REORGANIZE PARTITION p0,p1 INTO (PARTITION p0 VALUES LESS THAN (6000000));
将原来的 p0,p1 分区合并起来，放到新的 p0 分区中。
o LIST 分区重建
[sql]
ALTER TABLE users REORGANIZE PARTITION p0,p1 INTO (PARTITION p0 VALUES IN(0,1,4,5,8,9,12,13));
将原来的 p0,p1 分区合并起来，放到新的 p0 分区中。
o HASH/KEY 分区重建
[sql]
ALTER TABLE users REORGANIZE PARTITION COALESCE PARTITION 2;
用 REORGANIZE 方式重建分区的数量变成2，在这里数量只能减少不能增加。想要增加可以用 ADD PARTITION 方法。
* 新增分区
o 新增 RANGE 分区
[sql]
ALTER TABLE category ADD PARTITION (PARTITION p4 VALUES IN (16,17,18,19)
DATA DIRECTORY = '/data8/data'
INDEX DIRECTORY = '/data9/idx');
新增一个RANGE分区。
o 新增 HASH/KEY 分区
[sql]
ALTER TABLE users ADD PARTITION PARTITIONS 8;
将分区总数扩展到8个。
[ 给已有的表加上分区 ]
[sql]
alter table results partition by RANGE (month(ttime))
(PARTITION p0 VALUES LESS THAN (1),
PARTITION p1 VALUES LESS THAN (2) , PARTITION p2 VALUES LESS THAN (3) ,
PARTITION p3 VALUES LESS THAN (4) , PARTITION p4 VALUES LESS THAN (5) ,
PARTITION p5 VALUES LESS THAN (6) , PARTITION p6 VALUES LESS THAN (7) ,
PARTITION p7 VALUES LESS THAN (8) , PARTITION p8 VALUES LESS THAN (9) ,
PARTITION p9 VALUES LESS THAN (10) , PARTITION p10 VALUES LESS THAN (11),
PARTITION p11 VALUES LESS THAN (12),
PARTITION P12 VALUES LESS THAN (13) );
默认分区限制分区字段必须是主键（PRIMARY KEY)的一部分，为了去除此
限制：
[方法1] 使用ID
[sql]
mysql> ALTER TABLE np_pk
-> PARTITION BY