Mysql --分区表(1)

检查是否支持分区

通过如下命令检查的Mysql是否支持partition

mysql> SHOW PLUGINS;
...
| ARCHIVE                    | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     |
| partition                  | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     |
+----------------------------+----------+--------------------+---------+---------+
42 rows in set (0.12 sec)

或者通过查询 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';

+--------------------+---------+----------+
| Name               | Version | Status   |
+--------------------+---------+----------+
| binlog             | 1.0     | ACTIVE   |
| MEMORY             | 1.0     | ACTIVE   |
| MRG_MYISAM         | 1.0     | ACTIVE   |
| CSV                | 1.0     | ACTIVE   |
| MyISAM             | 1.0     | ACTIVE   |
| FEDERATED          | 1.0     | DISABLED |
| InnoDB             | 5.6     | ACTIVE   |
| BLACKHOLE          | 1.0     | ACTIVE   |
| PERFORMANCE_SCHEMA | 0.1     | ACTIVE   |
| ARCHIVE            | 3.0     | ACTIVE   |
| partition          | 1.0     | ACTIVE   |
+--------------------+---------+----------+
11 rows in set (0.01 sec)

由Oracle提供的MySQL 5.6社区版二进制是提供了分区功能支持的

如果你是源码安装，在cmake时要指定 -DWITH_PARTITION_STORAGE_ENGINE

如果你想disable分区支持，你可以在启动MySQL时附加–skip-partition选项

MERGE, CSV, or FEDERATED不支持创建分区表

注意

ENGINE子句要用在partitioning options前

CREATE TABLE ti (id INT, amount DECIMAL(7,2), tr_date DATE)
ENGINE=INNODB
PARTITION BY HASH( MONTH(tr_date) )
PARTITIONS 6;

无论哪种MySQL分区类型,要么分区表上没有主键/唯一键，要么分区表的主键/唯一键都必须包含分区键，也就是说不能使用主键/唯一键字段之外的其他字段分区。

下表不能分区，因为唯一键中没有包含分区键id列，即便该列为主键

CREATE TABLE tnp (
id INT NOT NULL AUTO_INCREMENT,
ref BIGINT NOT NULL,
name VARCHAR(255),
PRIMARY KEY pk (id),
UNIQUE KEY uk (name)
)
partition by range (id) (
partition p0 values less than(10),
partition p1 values less than(20),
partition p2 values less than(30)
);
ERROR 1503 (HY000): A UNIQUE INDEX must include all columns in the table's partitioning function

CREATE TABLE tnp (
id INT NOT NULL AUTO_INCREMENT,
ref BIGINT NOT NULL,
name VARCHAR(255),
PRIMARY KEY pk (id),
UNIQUE KEY uk (id,name)
)
partition by range (id) (
partition p0 values less than(10),
partition p1 values less than(20),
partition p2 values less than(30)
);

MySQL支持只查询某个分区的数据

( DELETE, INSERT, REPLACE, UPDATE, and LOAD DATA, LOAD XML 也支持Partition selection)

CREATE TABLE tnp (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(255),
PRIMARY KEY pk (id)
)
partition by range (id) (
partition p0 values less than(10),
partition p1 values less than(20),
partition p2 values less than(30)
);

mysql> insert into tnp values(1,'fan'),(11,'bo'),(21,'shi');
Query OK, 3 rows affected (0.02 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select * from tnp;
+----+------+
| id | name |
+----+------+
|  1 | fan  |
| 11 | bo   |
| 21 | shi  |
+----+------+
3 rows in set (0.00 sec)

mysql> select * from tnp partition(p0,p2);
+----+------+
| id | name |
+----+------+
|  1 | fan  |
| 21 | shi  |
+----+------+
2 rows in set (0.00 sec)