白话MyCat——MyCat部署运行（Linux环境）与使用步骤详解

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)