| 背景
需求来源
MySQL越来越流行，而且存储在MySQL的数据量也越来越大，单表数据达亿行已经是非常常见的现象，而这些表里面保存了大量的历史记录，严重影响SQL执行的效率。本文是针对客户需求，迁移MySQL Innodb大表分区中部分历史归档分区到其他实例或者其他库表，而且迁移过程尽量减少对业务环境的影响。
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环境介绍
MySQL 5.7.21
Centos 7.4
innodb_file_per_table=1
| MySQL常用的Innodb迁移方法
MySQL Enterprise Backup（物理备份，类似于xtrabackup）
Copying Data Files (冷备份)
逻辑导出和导入(mysqldump,mydumper,mysqlpump)
可传输的表空间
| 迁移方案（可传输的表空间）
准备工作
操作步骤
查看需要迁移表（原表）结构
root@localhost : testdba 02:03:18> use test
Database changed
root@localhost : test 08:37:50> show create table sbtest2;
+---------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+---------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| sbtest2 | CREATE TABLE `sbtest2` (
`id` int(10) DEFAULT NULL,
`name` varchar(20) COLLATE utf8_bin DEFAULT NULL,
`date` int(20) DEFAULT NULL,
KEY `idx_fenqu` (`date`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin
/*!50100 PARTITION BY RANGE (date)
(PARTITION p0 VALUES LESS THAN (20161201) ENGINE = InnoDB,
PARTITION p1 VALUES LESS THAN (20170101) ENGINE = InnoDB,
PARTITION p2 VALUES LESS THAN (20170201) ENGINE = InnoDB,
PARTITION p3 VALUES LESS THAN (20170301) ENGINE = InnoDB,
PARTITION p4 VALUES LESS THAN (20170401) ENGINE = InnoDB,
PARTITION p5 VALUES LESS THAN (20170501) ENGINE = InnoDB,
PARTITION p6 VALUES LESS THAN (20170601) ENGINE = InnoDB,
PARTITION p7 VALUES LESS THAN (20170701) ENGINE = InnoDB,
PARTITION p8 VALUES LESS THAN (20170801) ENGINE = InnoDB,
PARTITION p9 VALUES LESS THAN (20170901) ENGINE = InnoDB,
PARTITION p10 VALUES LESS THAN (20171001) ENGINE = InnoDB,
PARTITION p11 VALUES LESS THAN (20171101) ENGINE = InnoDB,
PARTITION p12 VALUES LESS THAN (20171201) ENGINE = InnoDB,
PARTITION p13 VALUES LESS THAN (20180101) ENGINE = InnoDB,
PARTITION p14 VALUES LESS THAN (20180201) ENGINE = InnoDB,
PARTITION p15 VALUES LESS THAN (20180301) ENGINE = InnoDB,
PARTITION p16 VALUES LESS THAN (20180401) ENGINE = InnoDB,
PARTITION p17 VALUES LESS THAN (20180501) ENGINE = InnoDB,
PARTITION p18 VALUES LESS THAN (20180601) ENGINE = InnoDB,
PARTITION p19 VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */ |
+---------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
root@localhost : test 12:04:03> SELECT PARTITION_NAME, TABLE_ROWS FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME = 'sbtest2';
+----------------+------------+
| PARTITION_NAME | TABLE_ROWS |
+----------------+------------+
| p0 | 22 |
| p1 | 2 |
| p2 | 2 |
| p3 | 2 |
| p4 | 2 |
| p5 | 2 |
| p6 | 2 |
| p7 | 2 |
| p8 | 2 |
| p9 | 2 |
| p10 | 2 |
| p11 | 2 |
| p12 | 2 |
| p13 | 2 |
| p14 | 2 |
| p15 | 2 |
| p16 | 2 |
| p17 | 2 |
| p18 | 2 |
| p19 | 14 |
+----------------+------------+
20 rows in set (0.00 sec)
按照个人迁移分区表需求，可以把历史分区迁移到其他MySQL实例，也可以迁移到同一MySQL实例的其他库中。首先创建与原表相同表结构的分区表，在创建分区表时，我们只需要创建我们需要迁移的表分区结构。例：下面是迁移案例，由于只迁移2017年数据，所以表结构只创建了存储2017年数据的分区（也就是分区p2-p13）。
root@localhost : test 01:59:36> create database testdba;
Query OK, 1 row affected (0.12 sec)
root@localhost : test 01:59:44> use testdba;
Database changed
root@localhost : testdba 06:04:26> CREATE TABLE `sbtest2` (
-> id int(10),
-> name varchar(20),
-> date int(20),
-> key idx_fenqu(date)
-> )
-> PARTITION BY RANGE (date) (
-> PARTITION p2 VALUES LESS THAN (20170201),
-> PARTITION p3 VALUES LESS THAN (20170301),
-> PARTITION p4 VALUES LESS THAN (20170401),
-> PARTITION p5 VALUES LESS THAN (20170501),
-> PARTITION p6 VALUES LESS THAN (20170601),
-> PARTITION p7 VALUES LESS THAN (20170701),
-> PARTITION p8 VALUES LESS THAN (20170801),
-> PARTITION p9 VALUES LESS THAN (20170901),
-> PARTITION p10 VALUES LESS THAN (20171001),
-> PARTITION p11 VALUES LESS THAN (20171101),
-> PARTITION p12 VALUES LESS THAN (20171201),
-> PARTITION p13 VALUES LESS THAN (20180101)
-> );
Query OK, 0 rows affected (0.22 sec)
清除新表所有的分区独立表空间，为导入原表的分区独立表空间做准备
root@localhost : testdba 02:00:05> use testdba;
Database changed
root@localhost : testdba 02:00:23> ALTER TABLE sbtest2 DISCARD PARTITION p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13 TABLESPACE;
Query OK, 0 rows affected (0.27 sec)
在原表中执行FLUSH TABLES ... FOR EXPORT（在分区表空间传输没有完成之前，不要退出该会话或者执行unlock tables;操作），用来获取元数据校验文件.cfg和确保该表的脏页刷到磁盘，并加共享表锁
root@localhost : testdba 02:00:24> USE test;
Database changed
root@localhost : test 02:00:29> FLUSH TABLES test.sbtest2 FOR EXPORT;
Query OK, 0 rows affected (0.00 sec)
[root@slave test]# cd /var/lib/mysql/data/mydata/test
[root@slave test]# ls
db.opt sbtest2#P#p10.cfg sbtest2#P#p12.ibd sbtest2#P#p15.cfg sbtest2#P#p17.ibd sbtest2#P#p2.cfg sbtest2#P#p4.ibd sbtest2#P#p7.cfg sbtest2#P#p9.ibd
sbtest2#P#p0.cfg sbtest2#P#p10.ibd sbtest2#P#p13.cfg sbtest2#P#p15.ibd sbtest2#P#p18.cfg sbtest2#P#p2.ibd sbtest2#P#p5.cfg sbtest2#P#p7.ibd sbtest2.frm
sbtest2#P#p0.ibd sbtest2#P#p11.cfg sbtest2#P#p13.ibd sbtest2#P#p16.cfg sbtest2#P#p18.ibd sbtest2#P#p3.cfg sbtest2#P#p5.ibd sbtest2#P#p8.cfg
sbtest2#P#p1.cfg sbtest2#P#p11.ibd sbtest2#P#p14.cfg sbtest2#P#p16.ibd sbtest2#P#p19.cfg sbtest2#P#p3.ibd sbtest2#P#p6.cfg sbtest2#P#p8.ibd
sbtest2#P#p1.ibd sbtest2#P#p12.cfg sbtest2#P#p14.ibd sbtest2#P#p17.cfg sbtest2#P#p19.ibd sbtest2#P#p4.cfg sbtest2#P#p6.ibd sbtest2#P#p9.cfg
进入到原表ibd所在的目录下，把原表需要迁移的分区表空间和元数据校验文件.cfg传输到新表所在的位置，并赋予权限
[root@slave test]# cp sbtest2#P#p2.* sbtest2#P#p3.* sbtest2#P#p4.* sbtest2#P#p5.* sbtest2#P#p6.* sbtest2#P#p7.* sbtest2#P#p8.* sbtest2#P#p9.* sbtest2#P#p10.* sbtest2#P#p11.* sbtest2#P#p12.* sbtest2#P#p13.* /var/lib/mysql/data/mydata/testdba/
[root@slave test]# ls ../testdba/
db.opt sbtest2#P#p11.cfg sbtest2#P#p12.ibd sbtest2#P#p2.cfg sbtest2#P#p3.ibd sbtest2#P#p5.cfg sbtest2#P#p6.ibd sbtest2#P#p8.cfg sbtest2#P#p9.ibd
sbtest2#P#p10.cfg sbtest2#P#p11.ibd sbtest2#P#p13.cfg sbtest2#P#p2.ibd sbtest2#P#p4.cfg sbtest2#P#p5.ibd sbtest2#P#p7.cfg sbtest2#P#p8.ibd sbtest2.frm
sbtest2#P#p10.ibd sbtest2#P#p12.cfg sbtest2#P#p13.ibd sbtest2#P#p3.cfg sbtest2#P#p4.ibd sbtest2#P#p6.cfg sbtest2#P#p7.ibd sbtest2#P#p9.cfg
[root@slave test]# chown -R mysql:mysql /var/lib/mysql
切回到执行FLUSH TABLES ... FOR EXPORT语句窗口，释放共享表锁
root@localhost : test 02:00:29> USE test;
Database changed
root@localhost : test 02:01:07> UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)
进入新表所在的实例或新表所在的库，手动导入分区表空间，进行数据恢复（应用传输到新表的分区表空间）
root@localhost : test 02:01:07> USE testdba;
Database changed
root@localhost : testdba 02:01:14> ALTER TABLE sbtest2 IMPORT PARTITION p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13 TABLESPACE;
Query OK, 0 rows affected (0.62 sec)
表空间迁移完成，数据恢复完成，最后校验数据准确性
root@localhost : testdba 02:03:16> SELECT PARTITION_NAME, TABLE_ROWS FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME = 'sbtest2' and TABLE_SCHEMA='testdba';
+----------------+------------+
| PARTITION_NAME | TABLE_ROWS |
+----------------+------------+
| p2 | 2 |
| p3 | 2 |
| p4 | 2 |
| p5 | 2 |
| p6 | 2 |
| p7 | 2 |
| p8 | 2 |
| p9 | 2 |
| p10 | 2 |
| p11 | 2 |
| p12 | 2 |
| p13 | 2 |
+----------------+------------+
12 rows in set (0.00 sec)
| 总结
以上是我们使用MySQL的分区表空间传输方法，解决了分区表历史数据归档到其他实例或者同一实例其他库的问题。对比逻辑迁移方式mysqldump或者insert .. select ...方式速度更快，数据立即可用，而且对业务的影响更小。
| 作者简介
岳雷·沃趣科技数据库工程师
熟悉MySQL体系结构和innodb存储引擎工作原理；以及MySQL备份恢复、复制、数据迁移等技术；专注于MySQL、MariaDB开源数据库，喜好开源技术。
文章标题：MySQL分区如何迁移
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