mycat表拆分操作教程

1，迁移数据

举例说明，比如一个博客数据库数据表如下：
这里水平拆分，垂直拆分，只是做个简单的实验，真正的线上业务要根据情况，数据进行拆分。

CREATE TABLE category (

id INT NOT NULL AUTO_INCREMENT,

user_id INT NOT NULL,

name VARCHAR(200) NOT NULL,

PRIMARY KEY (id)

);

--标签

CREATE TABLE tag (

id INT NOT NULL AUTO_INCREMENT,

user_id INT NOT NULL,

name VARCHAR(100) NOT NULL,

PRIMARY KEY (id)

);

--文章

CREATE TABLE `article` (

`id` int(11) NOT NULL PRIMARY KEY ,

`user_id` int(11) NOT NULL,

`title` varchar(200) NOT NULL,

`abstract` text,

`content` text,

`publish_time` datetime NOT NULL,

`create_time` datetime NOT NULL,

`update_time` datetime NOT NULL,

`category_id` int(11) NOT NULL,

KEY `category_id` (`category_id`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8;

--标签

CREATE TABLE article_tags (

user_id INT NOT NULL,

article_id INT NOT NULL,

tag_id INT NOT NULL,

PRIMARY KEY (user_id,article_id,tag_id)

);

--用户信息

CREATE TABLE user_info (

id INT NOT NULL AUTO_INCREMENT,

email VARCHAR(200) NOT NULL,

name VARCHAR(200) NOT NULL,

password VARCHAR(100) NOT NULL,

create_time DATETIME NOT NULL,

update_time DATETIME NOT NULL,

last_login_time DATETIME NOT NULL,

PRIMARY KEY (id),

UNIQUE KEY (name)

);

--链接

CREATE TABLE link (

id INT NOT NULL AUTO_INCREMENT,

user_id INT NOT NULL,

name VARCHAR(100) NOT NULL,

url VARCHAR(300) NOT NULL,

PRIMARY KEY (id),

KEY (user_id)

);

将所有数据都迁移到mycat中，一共有4个数据库，blog01，blog02，blog_article01，blog_article02。
article，article_tags分别在blog_article01，blog_article02，按照uid进行水平拆分。
user_info表在blog01，link，category，tag在blog02数据库中。

CREATE DATABASE blog01 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

CREATE DATABASE blog02 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

CREATE DATABASE blog_article01 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

CREATE DATABASE blog_article02 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

#创建一共mycat数据库，存储mycat相关数据比如sequence。

CREATE DATABASE mycat DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

2，schema.xml,配置

<!DOCTYPE mycat:schema SYSTEM "schema.dtd">

<schema name="mycat" checkSQLschema="false" sqlMaxLimit="100">

<table name="MYCAT_SEQUENCE" primaryKey="name" type="global" dataNode="nodeUser" />

</schema>

<schema name="blog_user" checkSQLschema="false" sqlMaxLimit="100">

<table name="user_info" primaryKey="id" type="global" dataNode="nodeUser" />

</schema>

<schema name="blog_category" checkSQLschema="false" sqlMaxLimit="100">

<table name="category" primaryKey="id" type="global" dataNode="nodeCategory" />

<table name="tag" primaryKey="id" type="global" dataNode="nodeCategory" />

<table name="link" primaryKey="id" type="global" dataNode="nodeCategory" />

</schema>

<schema name="blog_article" checkSQLschema="false" sqlMaxLimit="100">

<table name="article" primaryKey="user_id" dataNode="nodeArticle01,nodeArticle02" rule="mod-long" />

<table name="article_tags" primaryKey="id" type="global" dataNode="nodeArticle01,nodeArticle02" />

</schema>

<dataNode name="nodeMycat" dataHost="dataHost01" database="mycat" />

<dataNode name="nodeUser" dataHost="dataHost01" database="blog01" />

<dataNode name="nodeCategory" dataHost="dataHost01" database="blog02" />

<dataNode name="nodeArticle01" dataHost="dataHost01" database="blog_article01" />

<dataNode name="nodeArticle02" dataHost="dataHost01" database="blog_article02" />

<dataHost name="dataHost01" maxCon="1000" minCon="10" balance="0"

writeType="0" dbType="mysql" dbDriver="native">

<heartbeat>select 1</heartbeat>

<writeHost host="hostM1" url="127.0.0.1:3306" user="root" password="root"/>

</dataHost>

</mycat:schema>

配置4个数据库连接，user_info做垂直拆分（配置type=global）。
blog_article，数据库进行水平拆分，拆分成两个数据库。
当设置成全局表的时候必须保证这个表在所有的数据库中，和配置的dataNode无关。
article规则配置：

<!DOCTYPE mycat:rule SYSTEM "rule.dtd">

<mycat:rule xmlns:mycat="http://org.opencloudb/">

<tableRule name="mod-long">

<rule>

<columns>user_id</columns>

<algorithm>mod-long</algorithm>

</rule>

</tableRule>

<function name="mod-long"

class="org.opencloudb.route.function.PartitionByMod">

<property name="count">2</property>

</function>

</mycat:rule>

配置service.xml:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mycat:server SYSTEM "server.dtd">

<mycat:server xmlns:mycat="http://org.opencloudb/">

<system>

<property name="defaultSqlParser">druidparser</property>

</system>

<user name="mycat">

<property name="password">mycat</property>

<property name="schemas">mycat,blog_user,blog_category,blog_article</property>

</user>

</mycat:server>

3，数据库sequence生成

牵扯到分库的时候就一定要由sequence生成，mysql的主键自增就不能使用了。
mycat的文档里面没有找到这部分的配置资料，但是找到了sequence的存储过程。
可以把这个存储过程存储到一个单独的数据库中，然后进行一次查询，再做入库。
存储过程地址：
https://github.com/MyCATApache/Mycat-doc/blob/master/%E5%85%A5%E9%97%A8%E6%8C%87%E5%8D%97/sequnce-sql.txt

DROP TABLE IF EXISTS MYCAT_SEQUENCE;

CREATE TABLE MYCAT_SEQUENCE ( name VARCHAR(50) NOT NULL, current_value INT NOT NULL, increment INT NOT NULL DEFAULT 100, PRIMARY KEY (name) ) ENGINE=InnoDB;

DROP FUNCTION IF EXISTS `mycat_seq_currval`;

DELIMITER ;;

CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_currval`(seq_name VARCHAR(50)) RETURNS varchar(64) CHARSET latin1

DETERMINISTIC

BEGIN

DECLARE retval VARCHAR(64);

SET retval="-999999999,null";

SELECT concat(CAST(current_value AS CHAR),",",CAST(increment AS CHAR) ) INTO retval FROM MYCAT_SEQUENCE WHERE name = seq_name;

RETURN retval ;

END

;;

DELIMITER ;

DROP FUNCTION IF EXISTS `mycat_seq_nextval`;

DELIMITER ;;

CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_nextval`(seq_name VARCHAR(50)) RETURNS varchar(64) CHARSET latin1

DETERMINISTIC

BEGIN

UPDATE MYCAT_SEQUENCE

SET current_value = current_value + increment WHERE name = seq_name;

RETURN mycat_seq_currval(seq_name);

END

;;

DELIMITER ;

DROP FUNCTION IF EXISTS `mycat_seq_setval`;

DELIMITER ;;

CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_setval`(seq_name VARCHAR(50), value INTEGER) RETURNS varchar(64) CHARSET latin1

DETERMINISTIC

BEGIN

UPDATE MYCAT_SEQUENCE

SET current_value = value

WHERE name = seq_name;

RETURN mycat_seq_currval(seq_name);

END

;;

DELIMITER ;

--同时增加权限，否则不能执行。

mysql> grant all privileges on *.* to root@"%" identified by ".";

Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

4，测试mycat数据库

–mycat数据库的ip是192.168.1.16，端口是8066。
mysql -umycat -pmycat -P8066 -h 192.168.1.16

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mysql> show databases;

+---------------+

| DATABASE |

+---------------+

| blog_article |

| blog_category |

| blog_user |

| mycat |

+---------------+

4 rows in set (0.00 sec)

mysql> use blog_user;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> show tables;

+---------------------+

| Tables in blog_user |

+---------------------+

| user_info |

+---------------------+

1 row in set (0.00 sec)

mysql> insert into user_info(email,`name`,password,create_time,update_time,last_login_time) values('zhangsan@126.com','zhangsan',password('123456'),now(),now(),now());

Query OK, 1 row affected (0.01 sec)

mysql> select * from user_info;

+

----+------------------+----------+-------------------------------------------+---------------------+---------------------+---------------------+

+

----+------------------+----------+-------------------------------------------+---------------------+---------------------+---------------------+

|  1 | zhangsan@126.com | zhangsan | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 | 2015-03-26 02:47:38 | 2015-03-26 02:47:38 | 2015-03-26 02:47:38 |

+

----+------------------+----------+-------------------------------------------+---------------------+---------------------+---------------------+

1 row in set (0.11 sec)

mysql> update user_info set name = 'lisi' where id = 1;

Query OK, 1 row affected (0.08 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> delete from user_info where name = 'lisi';

Query OK, 1 row affected (0.00 sec)

mysql> use blog_category;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> show tables;

+-------------------------+

| Tables in blog_category |

+-------------------------+

| category |

| link |

| tag |

+-------------------------+

3 rows in set (0.00 sec)

mysql> insert into tag(id,user_id,name) values(1,1,'java');

Query OK, 1 row affected (0.11 sec)

mysql> select * from tag;

+----+---------+------+

| id | user_id | name |

+----+---------+------+

| 1 | 1 | java |

+----+---------+------+

1 row in set (0.11 sec)

mysql> update tag set name = 'j2ee' where id = 1;

Query OK, 1 row affected (0.08 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> insert into tag(user_id,name) values(2,'mysql');

Query OK, 1 row affected (0.00 sec)

mysql> select * from tag;

+----+---------+-------+

| id | user_id | name |

+----+---------+-------+

| 1 | 1 | j2ee |

| 2 | 2 | mysql |

+----+---------+-------+

2 rows in set (0.00 sec)

mysql> delete from tag where id = 1;

Query OK, 1 row affected (0.00 sec)

mysql> use blog_article;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

mysql> insert into article(id,user_id,title,publish_time,create_time,update_time,category_id) \

-> values (1,1,'test1',now(),now(),now(),1),(2,1,'test2',now(),now(),now(),2),\

-> (3,1,'test3',now(),now(),now(),3),(4,2,'test4',now(),now(),now(),3);

Query OK, 4 rows affected (0.00 sec)

Records: 3 Duplicates: 0 Warnings: 0

mysql> select * from article;

+

----+---------+-------+----------+---------+---------------------+---------------------+---------------------+-------------+

| id | user_id | title | abstract | content | publish_time        | create_time         | update_time         | category_id |

+

----+---------+-------+----------+---------+---------------------+---------------------+---------------------+-------------+

| 4 | 2 | test4 | NULL | NULL | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 3 |

| 1 | 1 | test1 | NULL | NULL | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 1 |

| 2 | 1 | test2 | NULL | NULL | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 2 |

| 3 | 1 | test3 | NULL | NULL | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 2015-03-26 03:30:55 | 3 |

+

----+---------+-------+----------+---------+---------------------+---------------------+---------------------+-------------+

4 rows in set (0.00 sec)

mysql> update article set title = "new title" where user_id = 1 and id =2;

Query OK, 1 row affected (0.00 sec)

Rows matched: 1 Changed: 1 Warnings: 0

测试sequence生成：

mysql> INSERT INTO MYCAT_SEQUENCE VALUES ('article_seq', 1, 1);

1 row in set (0.06 sec)

mysql> SELECT MYCAT_SEQ_CURRVAL('article_seq');

+----------------------------------+

| MYCAT_SEQ_CURRVAL('article_seq') |

+----------------------------------+

| 1,1 |

+----------------------------------+

1 row in set (0.01 sec)

mysql> SELECT MYCAT_SEQ_SETVAL('article_seq', 2);

+------------------------------------+

| MYCAT_SEQ_SETVAL('article_seq', 2) |

+------------------------------------+

| 2,1 |

+------------------------------------+

1 row in set (0.01 sec)

mysql> SELECT MYCAT_SEQ_CURRVAL('article_seq');

+----------------------------------+

| MYCAT_SEQ_CURRVAL('article_seq') |

+----------------------------------+

| 2,1 |

+----------------------------------+

1 row in set (0.01 sec)

mysql> SELECT MYCAT_SEQ_NEXTVAL('article_seq');

+----------------------------------+

| MYCAT_SEQ_NEXTVAL('article_seq') |

+----------------------------------+

| 3,1 |

+----------------------------------+

1 row in set (0.01 sec)

mysql> SELECT MYCAT_SEQ_NEXTVAL('article_seq');

+----------------------------------+

| MYCAT_SEQ_NEXTVAL('article_seq') |

+----------------------------------+

| 4,1 |

+----------------------------------+

1 row in set (0.02 sec)

总结

mycat提供了数据库垂直拆分和水平拆分的方案，对于数据迁移可以按照id，user_id进行拆分。
也可以将数据分库存储，不拆分，但必须放到不同的库中（和水平拆分的分开）。
同时，如果进行拆分，则需要修改主键生成方式，目前看到mycat中提供一个sequence的存储过程，可以直接使用。