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  读写分离是借助MySQL中间件 ProxySQL 实现的
 ProxySQL 有两个版本：官方版和percona版，percona版是基于官方版基础上修改C++语言开发，轻量级但性能优异(支持处理千亿级数据)具有中间件所需的绝大多数功能，包括：

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1. 多种方式的读/写分离
2. 定制基于用户、基于schema、基于语句的规则对SQL语句进行路由
3. 缓存查询结果
4. 后端节点监控

准备

  实现读写分离前，先实现主从复制

  注意：slave节点需要设置read_only=1

主机	IP地址	类型
CentOS7.6	192.168.36.101	Master
CentOS7.6	192.168.36.103	Slave
CentOS7.6	192.168.36.104	ProxySQL

注：实验之前为保障实验顺利进行，请关闭主机的selinux以及防火墙服务

开始搭建

Master节点修改数据库配置文件

[root@Master ~]#cat /etc/my.cnf
[mysqld]
server_id=1     # 为Master节点设置一个全局唯一的ID号
binlog_format=row       # 基于行复制的数据库语句
log-bin=/data/bin/mysql-bin     # 启用二进制日志

重新启动数据库服务

[root@Master ~]#service mysqld restart
Restarting mysqld (via systemctl):                         [  OK  ]

Master节点上创建带有复制权限的用户账号

MariaDB [(none)]> grant replication slave on *.* to repluser@'192.168.36.%' identified by 'centos';
Query OK, 0 rows affected (0.00 sec)

查看Master的日志位置信息

MariaDB [mysql]> show master logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |    912372 |
+------------------+-----------+
1 row in set (0.00 sec)

Slave节点修改配置文件

[root@Slave-1 ~]#cat /etc/my.cnf
[mysqld]
server_id=2         # Slave节点设置全局唯一的ID号
read_only           # 只读

重新启动数据库服务

[root@Slave-1 ~]#systemctl restart mariadb

使用Master创建的复制权限的用户账号进行同步

MariaDB [(none)]> CHANGE MASTER TO
    -> MASTER_HOST='192.168.36.101',
    ->  MASTER_USER='repluser',
    ->  MASTER_PASSWORD='centos',
    ->  MASTER_PORT=3306,
    ->  MASTER_LOG_FILE='mysql-bin.000001',
    ->  MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.01 sec)

启动Slave线程

MariaDB [(none)]> slave start;
Query OK, 0 rows affected (0.00 sec)

查看线程是否启动

*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.36.101
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 7389
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 7673
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes      # 从节点的IO线程
            Slave_SQL_Running: Yes      # 从节点的SQL线程
....
        Seconds_Behind_Master: 0        # Master与SLave服务器差别延迟
.....
             Master_Server_Id: 1
1 row in set (0.00 sec)

检查数据同步情况

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.00 sec)

配置ProxySQL的YUM仓库

[root@ProxySQL ~]#cat < [proxysql_repo]
> name= ProxySQL YUM repository
> baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/\$releasever
> gpgcheck=1
> gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
> EOF
[proxysql_repo]
name= ProxySQL YUM repository
baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/$releasever
gpgcheck=1
gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key

安装ProxySQL

[root@ProxySQL ~]#yum install -y proxysql mariadb

启动ProxySQL

[root@ProxySQL ~]#rpm -ql proxysql
/etc/init.d/proxysql
...

由于proxysql启动脚本在init.d文件中，所以需要使用service启动
[root@ProxySQL ~]#service proxysql start
Starting ProxySQL: 2019-05-08 17:58:16 [INFO] Using config file /etc/proxysql.cnf
DONE!

端口查看

[root@ProxySQL ~]#netstat -at
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:mysql           0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:6032            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:6033            0.0.0.0:*               LISTEN
# 6033端口是接收远程用户的连接、6032端口是连接，管理接口

连接proxysql管理接口

[root@ProxySQL ~]#mysql -uadmin -padmin -P6032 -h227.0.0.1
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.30 (ProxySQL Admin Module)

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)]>

ProxySQL相当于小型的MySQL,自带：用户名admin、密码admin

添加主从节点的地址

# 添加Master节点
MySQL [(none)]> insert into mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.36.101',3306);
Query OK, 1 row affected (0.00 sec)

# 添加Slave节点
MySQL [(none)]> insert into mysql_servers(hostgroup_id,hostname,port) values(10,'192.168.36.103',3306);
Query OK, 1 row affected (0.00 sec)

# 查看添加信息
MySQL [(none)]> select *from mysql_servers;
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.36.101 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0  |         |
| 10           | 192.168.36.103 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0  |         |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
2 rows in set (0.00 sec)

在Master上创建ProxySQL管理的账号

MariaDB [(none)]> grant replication client on *.* to monitor@'192.168.36.%' identified by 'magedu';
Query OK, 0 rows affected (0.00 sec)

ProxySQL配置监控的用户名和密码设置，使其自动连接主从节点进行调整

MySQL [(none)]> set mysql-monitor_username='monitor';
Query OK, 1 row affected (0.00 sec)

MySQL [(none)]> set mysql-monitor_password='magedu';
Query OK, 1 row affected (0.00 sec)

使配置加载到内存中生效，并保存到磁盘中

MySQL [(none)]> load mysql variables to runtime;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> save mysql variables to disk;
Query OK, 97 rows affected (0.01 sec)

查看监控连接是否正常

MySQL [(none)]> select *from mysql_server_connect_log;
+----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
| hostname       | port | time_start_us    | connect_success_time_us | connect_error                                                           |
+----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
| 192.168.36.101 | 3306 | 1557312316296707 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.101 | 3306 | 1557312557263893 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.101 | 3306 | 1557312616308042 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.103 | 3306 | 1557312617121004 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.103 | 3306 | 1557312676308396 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.101 | 3306 | 1557312676936371 | 0                       | Access denied for user 'monitor'@'192.168.36.104' (using password: YES) |
| 192.168.36.101 | 3306 | 1557312694163848 | 2228                    | NULL                                                                    |
| 192.168.36.103 | 3306 | 1557312695077512 | 4613                    | NULL                                                                    |
| 192.168.36.103 | 3306 | 1557312754164398 | 1370                    | NULL                                                                    |
| 192.168.36.103 | 3306 | 1557312874168899 | 2204                    | NULL                                                                    |
| 192.168.36.101 | 3306 | 1557312874890981 | 2939                    | NULL                                                                    |
+----------------+------+------------------+-------------------------+-------------------------------------------------------------------------+
22 rows in set (0.00 sec)

设置分组信息

MySQL [(none)]> insert into mysql_replication_hostgroups values(10,20,"test");
Query OK, 1 row affected (0.00 sec)

查看读写组信息

MySQL [(none)]> select *from mysql_replication_hostgroups;
+------------------+------------------+---------+
| writer_hostgroup | reader_hostgroup | comment |
+------------------+------------------+---------+
| 10               | 20               | test    |
+------------------+------------------+---------+
1 row in set (0.00 sec)

配置生效并保存到磁盘

MySQL [(none)]> save mysql servers to disk;
Query OK, 0 rows affected (0.02 sec)

查看信息

MySQL [(none)]> select *from mysql_servers;
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname       | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 10           | 192.168.36.101 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0  |         |
| 20           | 192.168.36.103 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0  |         |
+--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
2 rows in set (0.00 sec)

在master上进行创建设置账户，让客户端连接中间的调度器

MariaDB [(none)]> grant all on *.* to sqluser@'192.168.36.%' identified by 'magedu';
Query OK, 0 rows affected (0.00 sec)

ProxySQL添加记录，将用户添加到mysql_users表中

MySQL [(none)]> insert into mysql_users(username,password,default_hostgroup) values('sqluser','magedu',10);
Query OK, 1 row affected (0.00 sec)

查看是否添加成功

MySQL [(none)]> select *from mysql_users;
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| username | password | active | use_ssl | default_hostgroup | default_schema | schema_locked | transaction_persistent | fast_forward | backend | frontend | max_connections|
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
| sqluser  | magedu   | 1      | 0       | 10                | NULL           | 0             | 1                      | 0            | 1       | 1        | 10000|
+----------+----------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+
1 row in set (0.00 sec)

保存配置

MySQL [(none)]> load mysql users to runtime;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> save mysql users to disk;
Query OK, 0 rows affected (0.01 sec)

启用一个客户端连接ProxySQL进行测试

[root@CentOS6 ~]# mysql -usqluser -pmagedu -h292.168.36.104 -P6033
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.5.30 (ProxySQL)

Copyright (c) 2000, 2013, 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>

查看连接到哪个主机

mysql> select @@server_id;
+-------------+
| @@server_id |
+-------------+
|           1 |
+-------------+
1 row in set (0.00 sec)

ProxySQL上定义调度规则

MySQL [(none)]> insert into mysql_query_rules
    -> (rule_id,active,match_digest,destination_hostgroup,apply) values
    -> (1,1,'^select.*from update$',10,1),(2,1,'^select',20,1);
Query OK, 2 rows affected (0.00 sec)

生效并存盘

MySQL [(none)]> load mysql query rules to runtime;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> save mysql query rules to disk;
Query OK, 0 rows affected (0.01 sec)

客户端进行读写分离测试

[root@CentOS6 ~]# mysql -usqluser -pmagedu -h292.168.36.104 -P6033 -e 'select @@server_id;'
+-------------+
| @@server_id |
+-------------+
|           2 |
+-------------+

[root@CentOS6 ~]# mysql -usqluser -pmagedu -h292.168.36.104 -P6033 -e 'begin;use db1;insert t1 values(1);select @@server_id;'
+-------------+
| @@server_id |
+-------------+
|           1 |
+-------------+

完工
新闻名称：应用MySQL读写分离以提高MySQL服务器的读写性能
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