Linux Mycat安装及MySQL读写分离的实现

以下是基本架构图，具体如下：

一、配置MySQL主从、主主，详情请查看（

MySQL主主同步：https://blog.csdn.net/baidu_38432732/article/details/80773634

MySQL主从同步：https://blog.csdn.net/baidu_38432732/article/details/80653873 ）

二、安装mycat

1、配置java环境

 [root@mysql ~]# tar -xf jdk-8u77-linux-x64.gz
 [root@mysql ~]# mkdir /usr/local/java
 [root@mysql ~]# mv jdk1.8.0_77/ /usr/local/java/
 [root@mysql ~]#vim /etc/profile

export JAVA_HOME=/usr/local/java/jdk1.8.0_77
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib/rt.jar
export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
 [root@mysql ~]#source /etc/profile

[root@mysql ~]#  java -version
java version "1.8.0_77"
Java(TM) SE Runtime Environment (build 1.8.0_77-b03)
Java HotSpot(TM) 64-Bit Server VM (build 25.77-b03, mixed mode)
说明此时Java环境已经部署成功

2、安装mycat

下载mycat包并安装（http://dl.mycat.io/1.6-RELEASE/Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz）

[root@mysql ~]#  wget http://dl.mycat.io/1.6-RELEASE/Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz

[root@mysql ~]#  tar -xf Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz

[root@mysql ~]#  mv mycat/ /usr/local/

[root@mysql mycat]#  cd /usr/local/mycat/

[root@mysql mycat]#  vim /etc/profile

export MYCAT_HOME=/usr/local/mycat
export PATH=$PATH:$MYCAT_HOME/bin

[root@mysql mycat]# source /etc/profile

此时安装完毕

3、配置mycat

[root@mysql mycat]# cd conf/

修改schema.xml文件

[root@mysql mycat]# vim schema.xml

       

                一下备注部分为分表，因目前没需要所以没有对分表进行配置

               
       
       
       
                                  writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
                show slave status
               
                       
               
               
       

修改 server.xml

[root@mysql conf]# vim server.xml

       
        0

       

       
                123456
                TESTDB

       

       
                456
                TESTDB
                true
       

show slave status 表示一种集群策略，只适用在一主一从的环境中，当主 down 掉， 从可以充当主和从

balance属性

balance=”0”, 不开启读写分离机制，所有读操作都发送到当前可用的 writeHost 上
balance=”1”，全部的 readHost 与 stand by writeHost 参与 select 语句的负载均衡
balance=”2”，所有读操作都随机的在 writeHost、 readhost 上分发。
balance=”3”， 所有读请求随机的分发到 wiriterHost 对应的 readhost 执行,writerHost 不负担读压力

writeType 属性

负载均衡类型，目前的取值有 3 种：
writeType=”0”, 所有写操作发送到配置的第一个 writeHost，第一个挂了切到还生存的第二个writeHost， 重新启动后已切换后的为准，切换记录在配置文件中:dnindex.properties
writeType=”1”，所有写操作都随机的发送到配置的 writeHost

writeType="2"，不执行写操作

switchType属性

-1 表示不自动切换

1 默认值，自动切换

2 基于MySQL主从同步的状态决定是否切换

3 基于MySQLgalarycluster的切换机制（适合集群）（1.4.1）

心跳语句为show status like‘wsrep%’

强调：

仅仅主从读写分离的配置：
 
 
 
       
     
     
                 dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"> 
        show slave status 
         
                           password="123456"> 
             
             
         
     

主挂掉之后自动切换到从的配置：
 
 
 
       
     
     
                 dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"> 
        show slave status 
         
                           password="123456"> 
             
             
         
                           password="123456"/> 
     

4、启动mycat，并查看是否启动

[root@mysql conf]# /usr/local/mycat/bin/mycat start

[root@mysql conf]# netstat -anptu |grep java
tcp        0      0 127.0.0.1:32000         0.0.0.0:*               LISTEN      3063/java          
tcp       0      0 :::42155                :::*                    LISTEN      3063/java          
tcp       0      0 :::34457                :::*                    LISTEN      3063/java          
tcp       0      0 :::1984                 :::*                    LISTEN      3063/java          
tcp       0      0 :::8066                 :::*                    LISTEN      3063/java          
tcp       0      0 :::9066                 :::*                    LISTEN      3063/java          
tcp       0      0 192.168.1.76:36158      192.168.1.127:3306      ESTABLISHED 3063/java          
tcp       0      0 192.168.1.76:35258      192.168.1.128:3306      ESTABLISHED 3063/java 

设置验证环境并验证

（1）、登陆mycat，建表并插入数据

[root@localhost ~]# mysql -uroot -h192.168.1.76 -P8066 -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use TESTDB;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> create table company(id int not null primary key,name varchar(50),addr varchar(255));

Query OK, 0 rows affected (0.01 sec)

mysql> insert into travelrecord(id,user_id,traveldate,fee,days) values(2000002, 'alex', '2018-06-08',500.0,3);
Query OK, 1 row affected (0.42 sec)

mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
1 rows in set (0.01 sec)

（2）、登陆主数据库服务器并验证刚插入的数据

[root@localhost ~]# mysql -uroot -p123456

Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 42
Server version: 5.6.39-log Source distribution

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
1 rows in set (0.00 sec)

mysql> flush privileges;

Query OK, 0 rows affected (0.01 sec)

同理登陆从服务器并在从服务器上插入数据以便验证读写分离

[root@localhost ~]# mysql -uroot -p123456
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 36
Server version: 5.6.39-log Source distribution

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use liuys;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select *  from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
1 rows in set (0.00 sec)

mysql> insert into travelrecord(id,user_id,traveldate,fee,days) values(2000001, 'alice', '2017-08-08',500.0,3);

Query OK, 1 row affected (0.42 sec)

mysql> select *  from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000001 | alice   | 2017-08-08 |  500 |    3 |
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
回到主服务器查看时，肯定无法查到该条数据

此时为主服务器

mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
1 rows in set (0.00 sec)

当我们回到mycat服务器时，又可以看到数据

[root@localhost ~]# mysql -uroot -h192.168.1.76 -P8066 -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use TESTDB;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000001 | alice   | 2017-08-08 |  500 |    3 |
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
3 rows in set (0.01 sec)

（4）、当停止从服务器时

[root@localhost ~]# /etc/init.d/mysqld stop
Shutting down MySQL.... SUCCESS! 

我们回到mycat服务器时此时数据就缺失了从服务器上刚插入的那条数据

[root@localhost ~]# mysql -uroot -h192.168.1.76 -P8066 -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use TESTDB;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 2000002 | alex    | 2018-06-08 |  500 |    3 |
+---------+---------+------------+------+------+
1 rows in set (0.01 sec)
此时说明数据只能在从服务器上读取

（4）、相反当我们停止主服务器确报错无法连接数据库我们人能读到数据

至此mycat读学分离已部署完毕