(1) 部署环境
mycat是java开发，linux上安装jdk。
Java Oracle官方下载地址为：（选择linux版本）
http://www.oracle.com/technetwork/java/javase/archive-139210.html
(2) 安装jdk环境
解压 jdk-8u162-linux-x64.tar.gz文件，并配置java的环境变量ux-x64.tar.gz
#tar xvf jdk-8u162-linux-x64.tar.gz
# mv jdk1.8.0_162/usr/local/
编辑/etc/profile文件
# vim /etc/profile 添加如下内容
export JAVA_HOME=/usr/local/jdk1.8.0_162 export PATH=$JAVA_HOME/bin:$PATH export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
# source /etc/profile --使/etc/profile文件生效
# java -version
java version "1.8.0_162" Java(TM) SE Runtime Environment (build 1.8.0_162) Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
（3） 安装mysql
MySQL官方下载地址如下：
http://dev.mysql.com/downloads/mysql/
# yum install -y mysql-community-server-5.6.26-2.el5.x86_64.rpm
启动MySQL
# /etc/init.d/mysqld start
Starting mysqld (via systemctl): [ OK ]
为root账户创建密码
# mysqladmin -u root password "123456"
建议为123456，后面MyCAT配置文件schema.xml中会用到
四、安装MyCAT
创建MyCAT用户并设置密码
# useradd mycat
# passwd mycat
解压MyCAT文件
# tar xvf Mycat-server-1.5-alpha-20151221110028-linux.tar.gz
# mv mycat/ /usr/local/
设置mycat目录的属主和属组
# chown -R mycat.mycat /usr/local/mycat/
四、测试MyCAT
首先在MySQL上创建三个数据库：db1，db2，db3。
mysql> create database db1; Query OK, 1 row affected (0.00 sec) mysql> create database db2; Query OK, 1 row affected (0.00 sec) mysql> create database db3; Query OK, 1 row affected (0.00 sec)
启动mycat服务
# cd /usr/local/mycat/bin/
# ./mycat start
Starting Mycat-server...
查看mycat服务是否启动
# ps -ef |grep mycat
root 9640 7257 0 22:47 pts/3 00:00:00 grep --color=auto mycat
并没有启动
查看日志
# cd /usr/local/mycat/logs/
# cat wrapper.log
STATUS | wrapper | 2016/01/07 22:44:23 | --> Wrapper Started as Daemon STATUS | wrapper | 2016/01/07 22:44:23 | Launching a JVM... ERROR | wrapper | 2016/01/07 22:44:25 | JVM exited while loading the application. INFO | jvm 1 | 2016/01/07 22:44:25 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: MySQL-Server1: MySQL-Server1: Name or service not known STATUS | wrapper | 2016/01/07 22:44:29 | Launching a JVM... ERROR | wrapper | 2016/01/07 22:44:29 | JVM exited while loading the application. INFO | jvm 2 | 2016/01/07 22:44:29 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: MySQL-Server1: MySQL-Server1: Name or service not known STATUS | wrapper | 2016/01/07 22:44:34 | Launching a JVM... ERROR | wrapper | 2016/01/07 22:44:34 | JVM exited while loading the application. INFO | jvm 3 | 2016/01/07 22:44:34 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: MySQL-Server1: MySQL-Server1: Name or service not known STATUS | wrapper | 2016/01/07 22:44:38 | Launching a JVM... ERROR | wrapper | 2016/01/07 22:44:38 | JVM exited while loading the application. INFO | jvm 4 | 2016/01/07 22:44:38 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: MySQL-Server1: MySQL-Server1: Name or service not known STATUS | wrapper | 2016/01/07 22:44:42 | Launching a JVM... ERROR | wrapper | 2016/01/07 22:44:43 | JVM exited while loading the application. INFO | jvm 5 | 2016/01/07 22:44:43 | Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown: java.net.UnknownHostException: MySQL-Server1: MySQL-Server1: Name or service not known FATAL | wrapper | 2016/01/07 22:44:43 | There were 5 failed launches in a row, each lasting less than 300 seconds. Giving up. FATAL | wrapper | 2016/01/07 22:44:43 | There may be a configuration problem: please check the logs. STATUS | wrapper | 2016/01/07 22:44:43 | <-- Wrapper Stopped
根据报错信息，怀疑主机名没有绑定
修改hosts文件，绑定主机名
# vim /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 192.168.244.144 MySQL-Server1
重新启动mycat服务
# cd /usr/local/mycat/bin/
# ./mycat start
这次mycat正常启动
# ps -ef |grep mycat
root 10725 1 0 22:54 ? 00:00:00 /usr/local/mycat/bin/./wrapper-linux-x86-64 /usr/local/mycat/conf/wrapper.conf wrapper.syslog.ident=mycat wrapper.pidfile=/usr/local/mycat/logs/mycat.pid wrapper.daemonize=TRUE wrapper.lockfile=/var/lock/subsys/mycat root 10881 7257 0 22:55 pts/3 00:00:00 grep --color=auto mycat
# mysql -utest -ptest -h127.0.0.1 -P8066 -DTESTDB
其中8066是mycat的监听端口，类似于mysql的3306端口，其中-u，-p，-h分别是用户名，密码和主机，-D是连接的逻辑库。
至于为什么是这些，这个跟配置文件有关。
红色部分表明连接的是mycat。
创建Travelrecord表
create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
插入数据
mysql> insert into travelrecord(id,user_id,traveldate,fee,days) values(1,'Victor',20160101,100,10); Query OK, 1 row affected (0.00 sec) mysql> insert into travelrecord(id,user_id,traveldate,fee,days) values(5000001,'Job',20160102,100,10); Query OK, 1 row affected (0.00 sec) mysql> insert into travelrecord(id,user_id,traveldate,fee,days) values(10000001,'Slow',20160103,100,10); Query OK, 1 row affected (0.00 sec)
至于ID为什么取三个值，这个与conf目录下autopartition-long.txt的定义有关，这个文件主要定义auto-sharding-long的规则。
# range start-end ,data node index # K=1000,M=10000. 0-500M=0 500M-1000M=1 1000M-1500M=2
我主要是测试在id取不同区间的值时，分片的效果。
下面来看看分片的效果
mysql> select * from db1.travelrecord; +----+---------+------------+------+------+ | id | user_id | traveldate | fee | days | +----+---------+------------+------+------+ | 1 | Victor | 2016-01-01 | 100 | 10 | +----+---------+------------+------+------+ 1 row in set (0.00 sec) mysql> select * from db2.travelrecord; +---------+---------+------------+------+------+ | id | user_id | traveldate | fee | days | +---------+---------+------------+------+------+ | 5000001 | Job | 2016-01-02 | 100 | 10 | +---------+---------+------------+------+------+ 1 row in set (0.00 sec) mysql> select * from db3.travelrecord; +----------+---------+------------+------+------+ | id | user_id | traveldate | fee | days | +----------+---------+------------+------+------+ | 10000001 | Slow | 2016-01-03 | 100 | 10 | +----------+---------+------------+------+------+ 1 row in set (0.00 sec)
果然是分配到三个不同的节点上了。
五，mycat的配置
用户名及密码设置:server.xml:
逻辑库中的定义表:schema.xml:
这里需要说一下, 因为bbs_color和bbs_brand表中的数据很少, 所以这里不需要分库分表, 直接设置成全局表就行, 也就是这两个表中的数据在1,2,3 库中都是一样的.
还有就是childTable, 我们拿bbs_product和bbs_sku来说, 因为商品product和库存bbs_sku是一对多的关系, 那么我们就希望商品id为1 的商品所对应的库存都是在同一个库中的, 这样查询的话就不用跨库了.
同样这里还有一个属性是rule="sharding-by-pattern", 那么接下来我们就要看下这里设定的规则了.
因为上面的schema标签中有定义的那么为babasport, 而且dataNode节点又分别指向dn1, dn2, dn3, 所以这里就可以做到对应了.
我们在项目连接的时候 直接是连接babasport的.
查看分片规则: rule.xml
这里指定算法为sharding-by-pattern.
查看算法sharding-by-pattern, 这里指定算法存储在partition-pattern.txt
这里是通过PartitionByPattern这个类来实现的, 这里是对512进行取模, 如果取模过程中出现异常, 那么就放到3库(0,1,2)中进行存储.
查看算法指定文件:
这里就可以一目了然的查看到 0-127 是放在1库中, 128-255 是放在2库中, 256-512 是放在3库中.
同样Mycat还支持动态扩容, 当我们的数据量越来越大时我们还可以加机器来分担压力
如果想看MyCAT具体会将数据分配到哪个节点上，可通过路由分析。
语法其实蛮简单，就是SQL语句前加上explain语句。
下面根据explain命令查看create语句和insert语句具体会分配到哪些Datanode上。
mysql> explain create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
+-----------+-----------------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-----------------------------------------------------------------------------------------------------------------------+
| dn1 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
| dn2 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
| dn3 | create table travelrecord (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int) |
+-----------+-----------------------------------------------------------------------------------------------------------------------+
3 rows in set (0.00 sec)
mysql> explain insert into travelrecord(id,user_id,traveldate,fee,days) values(1,'Victor',20160101,100,10);
+-----------+----------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+----------------------------------------------------------------------------------------------+
| dn1 | insert into travelrecord(id,user_id,traveldate,fee,days) values(1,'Victor',20160101,100,10) |
+-----------+----------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
mysql> explain insert into travelrecord(id,user_id,traveldate,fee,days) values(5000001,'Job',20160102,100,10);
+-----------+-------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------------------------------------------------------------------------------+
| dn2 | insert into travelrecord(id,user_id,traveldate,fee,days) values(5000001,'Job',20160102,100,10) |
+-----------+-------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> explain insert into travelrecord(id,user_id,traveldate,fee,days) values(10000001,'Slow',20160103,100,10);
+-----------+---------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------------------------------------------------+
| dn3 | insert into travelrecord(id,user_id,traveldate,fee,days) values(10000001,'Slow',20160103,100,10) |
+-----------+---------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)