關於Mysql分區表的介紹可以參考:
http://blog.csdn.net/jhq0113/article/details/44592865
關於Mysql分區表的創建可以參考:
http://blog.csdn.net/jhq0113/article/details/44593511
前面已經提過,Mysql支持4種表的分區,即RANGE與LIST、HASH與KEY,其中RANGE和LIST類似,按一種區間進行分區,HASH與KEY類似,是按照某種算法對字段進行分區。
RANGE與LIST分區管理:
案例:有一個聊天記錄表,用戶幾千左右,已經對錶按照用戶進行一定粒度的水平分割,現仍然有部分表存儲的記錄比較多,於是按照下列方式有對錶進行了分區,分區的好處是,可以動態改變分區,刪除分區後,數據也一同被刪除,如聊天記錄只保存兩年,那麼你就可以按照時間進行分區,定期刪除兩年前的分區,動態創建新的的分區就能做到很好的數據維護。
分區表創建的語句如下:
DROP TABLE IF EXISTS `msgss`;
CREATE TABLE `msgss` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT '表主鍵',
`sender` int(10) unsigned NOT NULL COMMENT '發送者ID',
`reciver` int(10) unsigned NOT NULL COMMENT '接收者ID',
`msg_type` tinyint(3) unsigned NOT NULL COMMENT '消息類型',
`msg` varchar(225) NOT NULL COMMENT '消息內容',
`atime` int(10) unsigned NOT NULL COMMENT '發送時間',
`sub_id` tinyint(3) unsigned NOT NULL COMMENT '部門ID',
PRIMARY KEY (`id`,`atime`,`sub_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
/*********分區信息**************/
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
)
);
上述語句創建了三個按照RANGE劃分的主分區,每個主分區下面有六個按照HASH劃分的子分區。
插入測試數據:
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',1514736089,7);
INSERT INTO `msgss`(`sender`,`reciver`,`msg_type`,`msg`,`atime`,`sub_id`) VALUES(1,2,0,'Hello HASH 5',1514736098,5);
進行分區分析:
EXPLAIN PARTITIONS SELECT * FROM msgss;
可以檢測到分區信息如下:
檢測分區數據分佈:
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;
結果:第一條語句只掃描了t0的所有子分區,第二條語句只掃描了t1的所有子分區,第三四條分別只掃描了t2的所有子分區,證明表的分區和數據分佈成功。
需求:目前已經是2017年,需要將2015年所有的聊天記錄刪除,但是保留2016年的聊天記錄,並且2017年的數據也能正常按照分區進行存儲。
實現以上需求,需要兩步,第一步刪除t0分區,第二步按照新規則重建分區。
刪除分區語句:
ALTER TABLE `msgss` DROP PARTITION t0;
重建分區語句:
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
)
);
查詢發現,15年的數據全部被刪除,剩餘的數據被重新分區並分佈。
未完。。。。