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MySQL复合分区_MySQL
2020-11-09 20:14:12 责编:小采
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到底还是开源软件,MySQL对复合分区的支持远远没有Oracle丰富。

在MySQL 5.6版本中,只支持RANGE和LIST的子分区,且子分区的类型只能为HASH和KEY。

譬如:

CREATE TABLE ts (id INT, purchased DATE)
 PARTITION BY RANGE( YEAR(purchased) )
 SUBPARTITION BY HASH( TO_DAYS(purchased) )
 SUBPARTITIONS 2 (
 PARTITION p0 VALUES LESS THAN (1990),
 PARTITION p1 VALUES LESS THAN (2000),
 PARTITION p2 VALUES LESS THAN MAXVALUE
 );

上述创建语句中,最外层是RANGE分区,分为3个区,里面是HASH子分区,分为2个区,这样,该表一共分了3*2=6个分区。

当然,也可以用SUBPARTITION语句来显示定义子分区。


CREATE TABLE ts (id INT, purchased DATE)
 PARTITION BY RANGE( YEAR(purchased) )
 SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
 PARTITION p0 VALUES LESS THAN (1990) (
 SUBPARTITION s0,
 SUBPARTITION s1
 ),
 PARTITION p1 VALUES LESS THAN (2000) (
 SUBPARTITION s2,
 SUBPARTITION s3
 ),
 PARTITION p2 VALUES LESS THAN MAXVALUE (
 SUBPARTITION s4,
 SUBPARTITION s5
 )
 );

注意:

1> 如果你在分区中使用了SUBPARTITION语句,则每个分区中都必须定义,且每个分区中子分区的数量必须保持一致。譬如以下两种用法就会报错:

CREATE TABLE ts (id INT, purchased DATE)
 PARTITION BY RANGE( YEAR(purchased) )
 SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
 PARTITION p0 VALUES LESS THAN (1990) (
 SUBPARTITION s0,
 SUBPARTITION s1
 ),
 PARTITION p1 VALUES LESS THAN (2000) (
 SUBPARTITION s2
 ),
 PARTITION p2 VALUES LESS THAN MAXVALUE (
 SUBPARTITION s3,
 SUBPARTITION s4
 )
 );


CREATE TABLE ts (id INT, purchased DATE)
 PARTITION BY RANGE( YEAR(purchased) )
 SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
 PARTITION p0 VALUES LESS THAN (1990) (
 SUBPARTITION s0,
 SUBPARTITION s1
 ),
 PARTITION p1 VALUES LESS THAN (2000),
 PARTITION p2 VALUES LESS THAN MAXVALUE (
 SUBPARTITION s2,
 SUBPARTITION s3
 )
 );

2> 在SUBPARTITION语句中,可指定该分区的物理位置。譬如:

CREATE TABLE ts (id INT, purchased DATE)
 PARTITION BY RANGE(YEAR(purchased))
 SUBPARTITION BY HASH( TO_DAYS(purchased) ) (
 PARTITION p0 VALUES LESS THAN (1990) (
 SUBPARTITION s0a
 DATA DIRECTORY = '/disk0'
 INDEX DIRECTORY = '/disk1',
 SUBPARTITION s0b
 DATA DIRECTORY = '/disk2'
 INDEX DIRECTORY = '/disk3'
 ),
 PARTITION p1 VALUES LESS THAN (2000) (
 SUBPARTITION s1a
 DATA DIRECTORY = '/disk4/data'
 INDEX DIRECTORY = '/disk4/idx',
 SUBPARTITION s1b
 DATA DIRECTORY = '/disk5/data'
 INDEX DIRECTORY = '/disk5/idx'
 ),
 PARTITION p2 VALUES LESS THAN MAXVALUE (
 SUBPARTITION s2a,
 SUBPARTITION s2b
 )
 );

以上这个创建语句,将不同的分区分布到不同的物理路径下,无疑会极大的分散IO,这一点还是蛮吸引人的。

可惜,在本机测试过程中,报“ERROR 1030 (HY000): Got error -1 from storage engine”错误,具体原因还不太清楚,怀疑是MySQL的bug。

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