MyCAT 可以视为“MySQL”集群的企业级数据库，用来替代昂贵的Oracle集群，其背后是阿里曾经开源的知名产品Cobar。MyCAT的目标是：低成本的将现有的单机数据库和应用平滑迁移到“云”端，解决数据存储和业务规模迅速增长情况下的数据瓶颈问题。
一、部署步骤详解
(1) 用命令行工具或图形化客户端，连接MYSQL，创建DEMO所用三个分片数据库； CREATE database db1; CREATE database db2; CREATE database db3;
(2) 修改my.inf新增以下语句，my.inf 一般会放在/etc/my.cnf 或 /etc/mysql/my.cnf，设置为Mysql大小写不敏感，否则可能会发生表找不到的问题。 lower_case_table_names = 1
(3) 解压Mycat-server-1.3.0.2-20150105144205-linux.tar.gz 到/usr/local/mycat
(4) 解压jdk-7u65-linux-i586.gz，拷贝jdk1.7.0_65 到/usr/local/mycat/
(5) 修改/usr/local/conf/wrap.conf 修改wrapper.java.command=java为上一步存放路径 wrapper.java.command=/usr/local/mycat/jdk1.7.0/bin/java
(6) 创建mycat 用户，改变目录权限为mycat useradd mycat chown -R mycat.mycat /usr/local/mycat
(7) 修改用户密码 passwd mycat 输入：
(8) 修改/usr/local/conf/schema.xml，URL、用户名、密码修改，其余不变 <writeHost host="hostM1" url="10.1.176.104:3306" user="root" password="www.com.workssys">
二、运行步骤详解
(1) 进入 /usr/local/mycat/bin （默认数据端口为8066，管理端口为9066） 执行./mycat start
(2) 进入logs目录，查看日志，如果wrapper.log 报错 java.net.BindException: Address already in use 杀掉正在执行的相关java进程 ps -ef|grep java kill -9 xxx
三、使用步骤详解 (1) 进入mysql bin目录/usr/local/mysql/bin/
(2) 登录mysql 执行以下命令 ./mysql -utest -ptest -h10.1.176.104 -P8066 -DTESTDB (mycat的用户账号和授权信息是在conf/server.xml文件中配置)
(3) 表创建测试： mysql> create table employee (id int not null primary key,name varchar(100),sharding_id int not null); Query OK, 0 rows affected (0.30 sec)
mysql> explain create table employee (id int not null primary key,name varchar(100),sharding_id int not null); +-----------+------------------------------------------------------------------------------------------------+ | DATA_NODE | SQL | +-----------+------------------------------------------------------------------------------------------------+ | dn1 | create table employee (id int not null primary key,name varchar(100),sharding_id int not null) | | dn2 | create table employee (id int not null primary key,name varchar(100),sharding_id int not null) | +-----------+------------------------------------------------------------------------------------------------+ 2 rows in set (0.04 sec)
(4) 客户端软件使用：navicat
创建mycat新连接：ip：10.1.176.104，用户名：test，密码：test，端口：8066 可看到TESTDB数据库下已创建表：employee
打开db1，db2 数据库也可看到已创建表employee
(5) 插入数据测试 mysql> insert into employee(id,name,sharding_id) values(1,'leader us',10000); ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect... Connection id: 6 Current database: TESTDB
Query OK, 1 row affected (0.03 sec)
mysql> explain insert into employee(id,name,sharding_id) values(1,'leader us',10000); +-----------+-----------------------------------------------------------------------+ | DATA_NODE | SQL | +-----------+-----------------------------------------------------------------------+ | dn1 | insert into employee(id,name,sharding_id) values(1,'leader us',10000) | +-----------+-----------------------------------------------------------------------+ 1 row in set (0.00 sec) (6) 根据规则auto-sharding-long（主键范围）进行分片测试 mysql> explain create table company(id int not null primary key,name varchar(100)); +-----------+---------------------------------------------------------------------+ | DATA_NODE | SQL | +-----------+---------------------------------------------------------------------+ | dn1 | create table company(id int not null primary key,name varchar(100)) | | dn2 | create table company(id int not null primary key,name varchar(100)) | | dn3 | create table company(id int not null primary key,name varchar(100)) | +-----------+---------------------------------------------------------------------+ 3 rows in set (0.01 sec)
(7) 三个分片上都插入了3条数据 mysql> explain insert into company(id,name) values(1,'hp'); +-----------+---------------------------------------------+ | DATA_NODE | SQL | +-----------+---------------------------------------------+ | dn1 | insert into company(id,name) values(1,'hp') | | dn2 | insert into company(id,name) values(1,'hp') | | dn3 | insert into company(id,name) values(1,'hp') | +-----------+---------------------------------------------+ 3 rows in set (0.00 sec)
(8) 确认是分片存储 mysql> select * from employee; +----+-----------+-------------+ | id | name | sharding_id | +----+-----------+-------------+ | 2 | me | 10010 | | 4 | mydog | 10010 | | 1 | leader us | 10000 | | 3 | mycat | 10000 | +----+-----------+-------------+ 4 rows in set (0.01 sec)
mysql> explain select * from employee; +-----------+----------------------------------+ | DATA_NODE | SQL | +-----------+----------------------------------+ | dn1 | SELECT * FROM employee LIMIT 100 | | dn2 | SELECT * FROM employee LIMIT 100 | +-----------+----------------------------------+ 2 rows in set (0.00 sec)
