MyCAT简易入门

Posted 2021-01-01 xiaocongcong888

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_79
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 "1.7.0_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.xml中会用到

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。

复制代码
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)
复制代码

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

复制代码
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
复制代码

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

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

复制代码
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)
复制代码
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

复制代码
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)
复制代码
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。

复制代码
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)
复制代码

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.xml是Mycat服务器参数调整和用户授权的配置文件

schema.xml是逻辑库定义和表以及分片定义的配置文件

rule.xml是分片规则的配置文件

分类: MyCAT
标签: Mysql, MyCAT
好文要顶 关注我 收藏该文
iVictor
关注 - 3
粉丝 - 224
+加关注
6 1
? 上一篇：如何部署Icinga客户端
? 下一篇：如何部署Icinga服务端
posted @ 2016-01-08 12:45 iVictor 阅读(51624) 评论(15) 编辑 收藏

评论
回复引用 #1楼 2016-12-07 00:23 | 坏~牧羊人
照着试了下，博主写的真好，谢谢分享
支持(0)反对(0)
回复引用 #2楼 2017-02-18 12:12 | 青春无语
谢谢分享
支持(0)反对(0)
回复引用 #3楼 2017-07-06 14:48 | 小钊
请问下 我用mycat链接mysql的时候一直报这个错：
[[email protected] ~]# mysql -utest -ptest -h127.0.0.1 -P8066 -DTEST
ERROR 1045 (HY000): Access denied for user ‘test‘ with host ‘127.0.0.1‘

请问下要怎么解决啊
支持(0)反对(0)
回复引用 #4楼[楼主] 2017-07-07 11:34 | iVictor
@ 小钊
看看你server.xml文件的内容是啥？
支持(0)反对(0)
回复引用 #5楼 2017-07-07 11:35 | 小钊
@ iVictor
已经解决了，谢谢楼主，关键是要配置下 test这个用户就可以了
支持(0)反对(0)
回复引用 #6楼 2017-08-22 11:33 | vip65535
来我的分布式群吗？542241455
支持(0)反对(0)
回复引用 #7楼 2017-12-26 10:18 | fyihdg
新手注意，要修改这里的配置：