Mycat实现读写分离

实验环境准备

# mycat-server 10.0.0.81
# mysql-master 10.0.0.82
# mysql-slave  10.0.0.83

# 关闭selinux和防火墙
# 时间同步

Mysql主从复制

主节点配置

# 修改配置文件
[root@centos82 ~]#vim /etc/my.cnf.d/mysql-server.cnf
server-id=2
log_bin

# 创建复制用账户
[root@centos82 ~]#mysql
mysql> create user slave@'10.0.0.%' identified by '744123'
    -> ;
Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave on *.* to slave@'10.0.0.%';
Query OK, 0 rows affected (0.01 sec)

# 查看binlog位置
mysql> show master logs;
+--------------------+-----------+
| Log_name           | File_size |
+--------------------+-----------+
| centos8-bin.000001 |       763 |
+--------------------+-----------+
1 row in set (0.00 sec)

# 开启通用日志，观察读写分离
[root@centos82 ~]#vim /etc/my.cnf
[mysqld]
general_log=ON

从节点配置

# 修改配置文件
[root@centos83 ~]#vim /etc/my.cnf.d/mysql-server.cnf
server-id=3

# 指向主节点
[root@centos83 ~]#mysql

mysql> CHANGE MASTER TO
    ->   MASTER_HOST='10.0.0.82',
    ->   MASTER_USER='slave',
    ->   MASTER_PASSWORD='744123',
    ->   MASTER_PORT=3306,
    ->   MASTER_LOG_FILE='centos8-bin.000001',
    ->   MASTER_LOG_POS=763;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

# 开启slave复制线程
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

# 查看slave状态
root@localhost [(none)]>show slave statusG
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.0.0.82
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: centos8-bin.000001
          Read_Master_Log_Pos: 763
               Relay_Log_File: centos8-relay-bin.000002
                Relay_Log_Pos: 322
        Relay_Master_Log_File: centos8-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 763
              Relay_Log_Space: 531
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File:
           Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
               Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Master_Server_Id: 2
                  Master_UUID: b2fbbf25-1cfd-11eb-8651-000c293c4f1b
             Master_Info_File: /data/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Master_SSL_Crl:
           Master_SSL_Crlpath:
           Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position: 0
         Replicate_Rewrite_DB:
                 Channel_Name:
           Master_TLS_Version:
1 row in set (0.00 sec)

# 开启通用日志，观察读写分离
[root@centos83 ~]#vim /etc/my.cnf
[mysqld]
general_log=ON

创建数据库和用户并测试主从复制

# 主节点创建wordpress数据库和wpuser用户。
[root@centos82 ~]#mysql -uroot -p744123
mysql: [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 2
Server version: 5.7.30-log MySQL Community Server (GPL)

Copyright (c) 2000, 2020, 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.

root@localhost [(none)]>create database wordpress;
Query OK, 1 row affected (0.00 sec)

root@localhost [(none)]>create user wpuser@'10.0.0.%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)

root@localhost [(none)]>grant all on wordpress.* to wpuser@'10.0.0.%';
Query OK, 0 rows affected (0.00 sec)

# 查看从节点是否复制成功
root@localhost [(none)]>show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| wordpress          |
+--------------------+
5 rows in set (0.00 sec)

root@localhost [(none)]>show grants for wpuser@'10.0.0.%';
+--------------------------------------------------------------+
| Grants for wpuser@10.0.0.%                                   |
+--------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'wpuser'@'10.0.0.%'                    |
| GRANT ALL PRIVILEGES ON `wordpress`.* TO 'wpuser'@'10.0.0.%' |
+--------------------------------------------------------------+
2 rows in set (0.00 sec)

# 没有问题

安装Mycat并启动

# 安装java和mysql客户端
[root@centos81 ~]#dnf -y install java mariadb
[root@centos81 ~]#java -version
openjdk version "1.8.0_272"
OpenJDK Runtime Environment (build 1.8.0_272-b10)
OpenJDK 64-Bit Server VM (build 25.272-b10, mixed mode)

# 下载mycat
[root@centos81 ~]#wget http://dl.mycat.org.cn/1.6.7.4/Mycat-server-1.6.7.4-release/Mycat-server-1.6.7.4-release-20200105164103-linux.tar.gz

# 解压缩
[root@centos81 ~]#tar xvf Mycat-server-1.6.7.4-release-20200105164103-linux.tar.gz -C /usr/local/

# 配置环境变量
[root@centos81 ~]#echo 'PATH=/usr/local/mycat/bin:$PATH' > /etc/profile.d/mycat.sh
[root@centos81 ~]#. /etc/profile.d/mycat.sh

# 启动mycat，内存建议2G以上
[root@centos81 ~]#mycat start
Starting Mycat-server...

# 查看端口
[root@centos81 ~]#ss -nlt
State      Recv-Q     Send-Q         Local Address:Port            Peer Address:Port
LISTEN     0          128                  0.0.0.0:22                   0.0.0.0:*
LISTEN     0          1                  127.0.0.1:32000                0.0.0.0:*
LISTEN     0          100                        *:9066                       *:*
LISTEN     0          128                     [::]:22                      [::]:*
LISTEN     0          50                         *:33851                      *:*
LISTEN     0          50                         *:1984                       *:*
LISTEN     0          100                        *:8066                       *:*
LISTEN     0          50                         *:45731                      *:*

# 查看日志，mycat启动成功
[root@centos81 ~]#tail /usr/local/mycat/logs/wrapper.log 
STATUS | wrapper  | 2020/11/02 19:41:48 | --> Wrapper Started as Daemon
STATUS | wrapper  | 2020/11/02 19:41:48 | Launching a JVM...
INFO   | jvm 1    | 2020/11/02 19:41:48 | Wrapper (Version 3.2.3) http://wrapper.tanukisoftware.org
INFO   | jvm 1    | 2020/11/02 19:41:48 |   Copyright 1999-2006 Tanuki Software, Inc.  All Rights Reserved.
INFO   | jvm 1    | 2020/11/02 19:41:48 |
INFO   | jvm 1    | 2020/11/02 19:41:49 | MyCAT Server startup successfully. see logs inlogs/mycat.log

# 使用mycat默认用户和密码连接mycat
[root@centos81 apps]#mysql -uroot -p123456 -h 10.0.0.81 -P8066
Welcome to the MariaDB monitor.  Commands end with ; or g.
Your MySQL connection id is 3
Server version: 5.6.29-mycat-1.6.7.4-release-20200105164103 MyCat Server (OpenCloudDB)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

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

MySQL [(none)]> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB   |
+----------+
1 row in set (0.002 sec)

# 可以看到有个默认的TESTDB逻辑数据库。

配置Mycat实现主从读写分离

修改Mycat的连接信息和逻辑数据库

[root@centos81 ~]#vim /usr/local/mycat/conf/server.xml
...省略...
<user name="root" defaultAccount="true">
        <property name="password">123456</property>
        <property name="schemas">wordpress</property>
        <property name="defaultSchema">wordpress</property>
        <!--No MyCAT Database selected 错误前会尝试使用该schema作为schema，不设置则为null,报错 -->

        <!-- 表级 DML 权限设置 -->
        <!--
        <privileges check="false">
            <schema name="TESTDB" dml="0110" >
                <table name="tb01" dml="0000"></table>
                <table name="tb02" dml="1111"></table>
            </schema>
        </privileges>
         -->
    </user>
# 将下面另一个user设置删除，或者将其schemas与defaultSchema也改为wordpress，否则重启mycat会报错。

配置读写分离

[root@centos81 ~]#vim /usr/local/mycat/conf/schema.xml
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
    <schema name="wordpress" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1"></schema>
    <dataNode name="dn1" dataHost="localhost1" database="wordpress" />
    <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
        <heartbeat>select user()</heartbeat>
        <writeHost host="host1" url="10.0.0.82:3306" user="wpuser" password="123456">
        <readHost host="host2" url="10.0.0.83:3306" user="wpuser" password="123456"/>
        </writeHost>
    </dataHost>
</mycat:schema>

重启mycat并测试读写分离

[root@centos81 apps]#mycat restart
Stopping Mycat-server...
Stopped Mycat-server.
Starting Mycat-server...

[root@centos82 apps]#mysql -uroot -p123456 -h 10.0.0.81 -P 8066
Welcome to the MariaDB monitor.  Commands end with ; or g.
Your MySQL connection id is 1
Server version: 5.6.29-mycat-1.6.7.4-release-20200105164103 MyCat Server (OpenCloudDB)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

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

MySQL [(none)]> show databases;
+-----------+
| DATABASE  |
+-----------+
| wordpress |
+-----------+
1 row in set (0.001 sec)

MySQL [(none)]> use wordpress
Database changed

MySQL [wordpress]> select @@server_id;
+-------------+
| @@server_id |
+-------------+
|           3 |				<<== 可以看到这里是从节点的server_id，证明是从从节点读的数据。
+-------------+
1 row in set (0.002 sec)

MySQL [wordpress]> create table t1(id int);
Query OK, 0 rows affected (0.007 sec)

# 查看主节点通用日志
[root@centos8 ~]#tail /data/mysql/centos8.log
2020-11-02T13:37:11.419395Z	    3 Query	SET @slave_uuid= '9c9d49c8-1cfd-11eb-b1cd-000c29c8e04f'
2020-11-02T13:37:11.419713Z	    3 Binlog Dump	Log: 'centos8-bin.000001'  Pos: 2279
2020-11-02T13:37:11.464746Z	    2 Query	select user()
2020-11-02T13:37:21.465091Z	    2 Query	select user()                  <<==  Mycat的心跳检查
2020-11-02T13:37:31.464749Z	    2 Query	select user()
2020-11-02T13:37:41.464749Z	    2 Query	select user()
2020-11-02T13:37:51.465218Z	    2 Query	select user()
2020-11-02T13:38:01.465218Z	    2 Query	select user()
2020-11-02T13:38:05.916088Z	    2 Query	create table t1(id int)        <<==  确实是在主节点上执行写操作
2020-11-02T13:38:11.465034Z	    2 Query	select user()

Mycat读写分离实现成功！