mysql 提供分区表的功能,可以将大表进行分拆,分拆后可以极大的提升查询能力。
备注:分区表的分区也可以部署到不同的物理磁盘。
下面是一个典型的RANGE分区例子:
1、创建数据库如下:
DROP TABLE IF EXISTS t_demo_test4; CREATE TABLE t_demo_test4( tid int(20) NOT NULL AUTO_INCREMENT, day datetime NOT NULL, title varchar(50), content varchar(200), PRIMARY KEY(tid, day) )PARTITION BY RANGE COLUMNS (day)( PARTITION P_3 VALUES LESS THAN ('2015-03-01'), PARTITION P_6 VALUES LESS THAN ('2015-06-01'), PARTITION P_9 VALUES LESS THAN ('2015-09-01'), PARTITION P_12 VALUES LESS THAN ('2015-12-31') );
2、插入数据:
insert into t_demo_test4(day, title, content) values('2015-04-05 22:10:30','title1','content sinny write test') ,('2015-05-05 22:10:30','title1','一种内容1') ,('2015-06-06 22:10:30','title1','一种内容2') ,('2015-07-07 22:10:30','title1','一种内容3') ,('2015-08-08 22:10:30','title1','一种内容4');
3、查询数据:
SELECT * FROM t_demo_test4 WHERE day < '2015-5-30';
通过explain查看:
可以看到此时,rows = 4,改搜索并未遍历全部数据。
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MYSQL还提供LIST、HASH、KEY三种分区方式,如下:
DROP TABLE IF EXISTS t_demo_test5; CREATE TABLE t_demo_test5( tid int(20) NOT NULL AUTO_INCREMENT, day datetime NOT NULL, type varchar(50), content varchar(200), PRIMARY KEY(tid,type) )PARTITION BY LIST COLUMNS(type)( PARTITION P_1 VALUES IN ('report','note'), PARTITION P_2 VALUES IN ('default') );
DROP TABLE IF EXISTS t_demo_test5; CREATE TABLE t_demo_test5( tid int(20) NOT NULL AUTO_INCREMENT, day datetime NOT NULL, type varchar(50), content varchar(200), PRIMARY KEY(tid) )PARTITION BY LINEAR HASH(tid) PARTITIONS 4;
DROP TABLE IF EXISTS t_demo_test5; CREATE TABLE t_demo_test5( tid int(20) NOT NULL AUTO_INCREMENT, day datetime NOT NULL, type varchar(50), content varchar(200), PRIMARY KEY(tid) )PARTITION BY LINEAR KEY(tid) PARTITIONS 4;