数据切分Mysql分区表的管理与维护_MySQL

RANGE与LIST分区管理：

案例：有一个聊天记录表，用户几千左右，已经对表按照用户进行一定粒度的水平分割，现仍然有部分表存储的记录比较多，于是按照下列方式有对表进行了分区，分区的好处是，可以动态改变分区，删除分区后，数据也一同被删除，如聊天记录只保存两年，那么你就可以按照时间进行分区，定期删除两年前的分区，动态创建新的的分区就能做到很好的数据维护。

分区表创建的语句如下：

DROP TABLE IF EXISTS `msgss`;
CREATE TABLE `msgss` (
 `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT '表主键',
 `sender` int(10) unsigned NOT NULL COMMENT '发送者ID',
 `reciver` int(10) unsigned NOT NULL COMMENT '接收者ID',
 `msg_type` tinyint(3) unsigned NOT NULL COMMENT '消息类型',
 `msg` varchar(225) NOT NULL COMMENT '消息内容',
 `atime` int(10) unsigned NOT NULL COMMENT '发送时间',
 `sub_id` tinyint(3) unsigned NOT NULL COMMENT '部门ID',
 PRIMARY KEY (`id`,`atime`,`sub_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
/*********分区信息**************/
PARTITION BY RANGE (atime) SUBPARTITION BY HASH (sub_id) 
(
	PARTITION t0 VALUES LESS THAN(1451577600)
	(
	SUBPARTITION s0,
	SUBPARTITION s1,
	SUBPARTITION s2,
	SUBPARTITION s3,
	SUBPARTITION s4,
	SUBPARTITION s5
	),
	PARTITION t1 VALUES LESS THAN(1483200000)
	(
	SUBPARTITION s6,
	SUBPARTITION s7,
	SUBPARTITION s8,
	SUBPARTITION s9,
	SUBPARTITION s10,
	SUBPARTITION s11
	),
	PARTITION t2 VALUES LESS THAN MAXVALUE
	(
	SUBPARTITION s12,
	SUBPARTITION s13,
	SUBPARTITION s14,
	SUBPARTITION s15,
	SUBPARTITION s16,
	SUBPARTITION s17
	)
);

上述语句创建了三个按照RANGE划分的主分区，每个主分区下面有六个按照HASH划分的子分区。

插入测试数据：

INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH',UNIX_TIMESTAMP(NOW()),1);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 2',UNIX_TIMESTAMP(NOW()),2);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 3',UNIX_TIMESTAMP(NOW()),3);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 10',UNIX_TIMESTAMP(NOW()),10);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 7',UNIX_TIMESTAMP(NOW()),7);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 5',UNIX_TIMESTAMP(NOW()),5);

INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH',1451577607,1);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 2',1451577609,2);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 3',1451577623,3);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 10',1451577654,10);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 7',1451577687,7);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 5',1451577699,5);

INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH',1514736056,1);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 2',1514736066,2);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 3',1514736076,3);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 10',1514736086,10);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 7',15147360,7);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 5',1514736098,5);

EXPLAIN PARTITIONS SELECT * FROM msgss;

可以检测到分区信息如下：

检测分区数据分布：

EXPLAIN PARTITIONS SELECT * FROM msgss WHERE `atime`<1451577600;

EXPLAIN PARTITIONS SELECT * FROM msgss WHERE `atime`>1451577600 AND `atime`<1483200000;

EXPLAIN PARTITIONS SELECT * FROM msgss WHERE `atime`>1483200000 AND `atime`<1514736000;

EXPLAIN PARTITIONS SELECT * FROM msgss WHERE `atime`>1514736000;

需求：目前已经是2017年，需要将2015年所有的聊天记录删除，但是保留2016年的聊天记录，并且2017年的数据也能正常按照分区进行存储。

实现以上需求，需要两步，第一步删除t0分区，第二步按照新规则重建分区。

删除分区语句：

ALTER TABLE `msgss` DROP PARTITION t0;

重建分区语句：

ALTER TABLE `msgss` PARTITION BY RANGE (atime) SUBPARTITION BY HASH (sub_id) 
(
	PARTITION t0 VALUES LESS THAN(1483200000)
	(
	SUBPARTITION s0,
	SUBPARTITION s1,
	SUBPARTITION s2,
	SUBPARTITION s3,
	SUBPARTITION s4,
	SUBPARTITION s5
	),
	PARTITION t1 VALUES LESS THAN(1514736000)
	(
	SUBPARTITION s6,
	SUBPARTITION s7,
	SUBPARTITION s8,
	SUBPARTITION s9,
	SUBPARTITION s10,
	SUBPARTITION s11
	),
	PARTITION t2 VALUES LESS THAN MAXVALUE
	(
	SUBPARTITION s12,
	SUBPARTITION s13,
	SUBPARTITION s14,
	SUBPARTITION s15,
	SUBPARTITION s16,
	SUBPARTITION s17
	)
);