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[数据库]MyCAT简易入门


MyCAT是mysql中间件,前身是阿里大名鼎鼎的Cobar,Cobar在开源了一段时间后,不了了之。于是MyCAT扛起了这面大旗,在大数据时代,其重要性愈发彰显。这篇文章主要是MyCAT的入门部署。

一、安装java

因Mycat是用java开发的,所以需要在实验环境下安装java,官方建议jdk1.7及以上版本

Java Oracle官方下载地址为:

http://www.oracle.com/technetwork/java/javase/archive-139210.html

 

解压jdk-7u79-linux-x64.tar.gz文件,并配置java的环境变量

# tar xvf jdk-7u79-linux-x64.tar.gz

# mv jdk1.7.0_79/ /usr/local/

 

编辑/etc/profile文件

# vim /etc/profile  添加如下内容

export JAVA_HOME=/usr/local/jdk1.7.0_79export PATH=$JAVA_HOME/bin:$PATHexport 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 "1.7.0_79"Java(TM) SE Runtime Environment (build 1.7.0_79-b15)Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

 

二、安装MySQL

MySQL官方下载地址如下:

http://dev.mysql.com/downloads/mysql/

里面有各种版本,包括RPM,二进制,源码包。

为了方便起见,我这里选择是RPM包

# 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.

 

三、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 DaemonSTATUS | 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 knownSTATUS | 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 knownSTATUS | 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 knownSTATUS | 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 knownSTATUS | 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 knownFATAL | 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.localdomain6192.168.244.144 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/mycatroot   10881  7257 0 22:55 pts/3  00:00:00 grep --color=auto mycat

 

下面以Travelrecord为例,来进行插入,查询,路由分析等基本操作。

首先利用mycat连接mysql数据库

# 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=0500M-1000M=11000M-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。

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)

 

总结:

关于MyCAT的配置其实是蛮简单的,最主要的是熟悉各配置文件的规则。以上用户名,密码,如何分库,都是在配置文件中定义的,后续,有时间再一一详表。

关于配置文件,conf目录下主要以下三个需要熟悉。

server.

schema.

rule.