读写分离原理

由MySQL代理面向客户提供服务

案例1：实现MySQL读写分离

1.1 问题

搭建一主一从结构
配置maxscale代理服务器
测试配置

使用4台虚拟机，如图-1所示。其中192.168.4.51和192.168.4.52，分别提供读、写服务，均衡流量，通过主从复制保持数据一致性，由MySQL代理192.168.4.57面向客户端提供服务，收到SQL写请求时，交给主服务器处理，收到SQL读请求时，交给从服务器处理。在客户机192.168.4.50测试配置。
在这里插入图片描述

步骤一：搭建MySQL一主一从同步结构

配置主服务器192.168.4.51

]# vim /etc/my.cnf
[mysqld]
server_id=51    //指定服务器ID号 
log-bin=master51        //启用binlog日志，并指定文件名前缀
...
[root@master10 ~]# systemctl restart mysqld        //重启mysqld

主服务器授权用户，并查看binlog日志信息

]# mysql -uroot -p123456
mysql> grant all on *.* to 'repluser'@'%' identified by '123456';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show master status;
+-----------------+----------+--------------+------------------+-------------------+
| File      | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-----------------+----------+--------------+------------------+-------------------+
| master51.000001 |      449 |              |                  |                   |
+-----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

配置从服务器192.168.4.52

]# vim /etc/my.cnf

[mysqld]
server_id=52 //指定服务器ID号，不要与Master的相同
:wq
]# systemctl restart mysqld

配置从服务器192.168.4.52，指定主服务器信息，日志文件、偏移位置（参考MASTER上的状态输出）

]# mysql -uroot -p123456
mysql> change master to master_host='192.168.4.51',
    -> master_user='repluser',
    -> master_password='123456',
    -> master_log_file='master51.000001',
    -> master_log_pos=449;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
mysql> show  slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.51
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: master51.000001
          Read_Master_Log_Pos: 738
               Relay_Log_File: slave20-relay-bin.000002
                Relay_Log_Pos: 319
        Relay_Master_Log_File: master51.000001
             Slave_IO_Running: Yes     //IO线程YES
            Slave_SQL_Running: Yes     //SQL线程YES
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
                      ..........
1 row in set (0.00 sec)

测试配置，在主服务器本机创建数据库 aa库

]# mysql –uroot –p123456
mysql> create database aa;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| aa                 |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

从服务器上查看，有aa库

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| aa                 |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

步骤二：配置maxscale代理服务器

环境准备

关闭防火墙和SElinux，保证yum源可以正常使用，安装提供服务的软件

]# rpm -ivh maxscale-2.1.2-1.rhel.7.x86_64.rpm         //安装maxscale
warning: maxscale-2.1.2-1.rhel.7.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 8167ee24: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...
   1:maxscale-2.1.2-1                 ################################# [100%]

修改主配置文件

]# vim /etc/maxscale.cnf
[maxscale]
threads=auto            //运行的线程的数量
[server1]            //定义数据库服务器
type=server
address=192.168.4.51        //主服务器ip
port=3306
protocol=MySQLBackend        
[server2]
type=server
address=192.168.4.52        //从服务器IP
port=3306
protocol=MySQLBackend
[MySQL Monitor]                //定义监控的数据库服务器
type=monitor
module=mysqlmon
servers=server1, server2        //监控的数据库列表，不能写ip
user=maxscalemon                    //监控用户
passwd=123qqq...A                //密码
monitor_interval=10000        
#[Read-Only Service]        //不定义只读服务
#type=service
#router=readconnroute
#servers=server1
#user=myuser
#passwd=mypwd
#router_options=slave
[Read-Write Service]            //定义读写分离服务
type=service
router=readwritesplit
servers=server1, server2
user=maxscalerouter            //路由用户
passwd=123qqq…A                //密码
max_slave_connections=100%
[MaxAdmin Service]        //定义管理服务
type=service
router=cli
#[Read-Only Listener]        //不定义只读服务使用的端口号
#type=listener
#service=Read-Only Service
#protocol=MySQLClient
#port=4008
[Read-Write Listener]            //定义读写服务使用的端口号
type=listener
service=Read-Write Service
protocol=MySQLClient
port=4006
[MaxAdmin Listener]        //管理服务使用的端口号
type=listener
service=MaxAdmin Service
protocol=maxscaled
socket=default
port=4016     //手动添加，不指定时使用的是默认端口在启动服务以后可以知道默认端口是多少

添加授权用户

根据maxscale.cnf文件配置，在主/从服务器上添加对应的授权用户，因为2台数据库服务器是主从同步结构，只在主数据库服务器添加用户即可，从服务器会自动同步

mysql> grant replication slave,replication client on *.* to  maxscalemon@'%' identified by "123qqq…A"; //授权监控用户
mysql> grant select on mysql.* to maxscalerouter@"%" identified by "123qqq…A"; //授权路由用户

查看授权用户

分别在主/从服务器上面查看

mysql> select user,host from mysql.user where user like “maxscale%”;
+----------------+------+
| user           | host |
+----------------+------+
| maxscalemon    | %    |
| maxscalerouter | %    |
+----------------+------+
2 rows in set (0.00 sec)

在代理服务器57主机，测试授权用户

]# yum -y  install mariadb  //安装提供mysql命令的软件包
]# mysql -h 192.168.4.51 -umaxscalemon -p123qqq…A
]# mysql -h 192.168.4.52 -umaxscalemon -p123qqq…A
]# mysql -h 192.168.4.51 -umaxscalerouter -p123qqq…A
]# mysql -h 192.168.4.52 -umaxscalerouter -p123qqq…A

启动服务代理服务

]# maxscale -f  /etc/maxscale.cnf   
]# ps -C  maxscale        //查看进程
PID TTY          TIME CMD
17930 ?        00:00:00 maxscale   
]# netstat  -antup | grep :4006  //查看读写分离端口
tcp6       0      0 :::4006      :::*                    LISTEN      17930/maxscale
]# netstat  -antup | grep :4016  //查看管理服务端口
tcp6       0      0 :::4016       :::*                    LISTEN      17930/maxscale

步骤三：测试配置

查看监控信息（在主机57 本机自己访问自己）

]# maxadmin  -uadmin -pmariadb -P4016
MaxScale> list  servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server             | Address         | Port  | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1            | 192.168.4.51    |  3306 |           0 | Master, Running
server2            | 192.168.4.52    |  3306 |           0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------

在主服务器上添加访问数据连接用户

在主服务器添加即可，从服务器会自动同步数据

mysql> create database gamedb;
mysql> create table gamedb.a(id int);
mysql> grant select,insert on  gamedb.* to  yaya66@"%" identified by "123qqq...A";

客户端连接代理服务57 访问数据

]# mysql -h192.168.4.57 -P4006 -uyaya66 -p123qqq...A
mysql> select * from gamedb.a;
mysql> insert into gamedb.a values(99);
mysql> select * from gamedb.a;
mysql> select * from gamedb.a;
Empty set (0.00 sec)
mysql> insert into gamedb.a values(99);
Query OK, 1 row affected (0.06 sec)
mysql>
mysql> select * from gamedb.a;
+------+
|  id  |
+------+
|  99  |
+------+
1 row in set (0.00 sec)

验证57主机的数据读写分离功能

在从服务器添加新纪录

Mysql> insert into gamedb.values(52);
Mysql> select * from mysql> select * from gamedb.a;
+------+
|  id  |
+------+
|  99  |
|  52  |
+------+

在主服务器查看记录

Mysql> select * from mysql> select * from gamedb.a;
+------+
|  id  |
+------+
|  99  |
+------+

客户端连接代理服务器57 访问数据

]# mysql -h192.168.4.57 -P4006 -uyaya66 -p123qqq...A
Mysql> select * from mysql> select * from gamedb.a;
+------+
|  id  |
+------+
|  99  |
|  52  |
+------+

什么是多实例 :

在一台服务器上运行多个数据库

为什么要使用多实例

节约运维成本
提高硬件利用率

案例2：配置MySQL多实例

2.1 问题

在主机192.168.4.57上：

配置第1个MySQL实例

实例名称mysqld1、端口3307
数据库目录/dir2、pid文件mysqld1.pid
错误日志mysqld1.err、socket文件mysqld1.socket

配置第2个MySQL实例

实例名称mysqld2、端口3308
数据库目录/dir1、pid文件mysqld2.pid
错误日志mysqld2.err、socket文件mysqld2.socket

步骤一：配置多实例（192.168.4.57上操作）

解压软件、修改目录名、设置PATH路径

`javascript:void(0)``powershell
]# yum –y  install libaio
]# useradd  mysql
]# tar -zxvf mysql-5.7.20-linux-glibc2.12-x86_64.tar.gz
]# mv mysql-5.7.20-linux-glibc2.12-x86_64 /usr/local/mysql
]# PATH=/usr/local/mysql/bin:$PATH
]# vim /etc/bashrc
export PATH=/usr/local/mysql/bin:$PATH

编辑主配置文件/etc/my.cnf

每个实例要有独立的数据库目录、监听端口号、实例名称和独立的sock文件

]# vim /etc/my.cnf
[mysqld_multi]        //启用多实例
mysqld = /usr/local/mysql/bin/mysqld_safe        //指定进程文件路径
mysqladmin = /usr/local/mysql/bin/mysqladmin    //指定管理命令路径
user = root        //指定进程用户
[mysqld1]        //实例进程名称
port=3307        //端口号
datadir=/dir1        //数据库目录 ，要手动创建
socket=/dir1/mysqld1.sock        //指定sock文件的路径和名称
pid-file=/dir1/mysqld1.pid        //进程pid号文件位置
log-error=/dir1/mysqld1.err        //错误日志位置 
[mysqld2]
port=3308
datadir=/dir2
socket=/dir2/mysqld2.sock
pid-file=/dir2/mysqld2.pid
log-error=/dir2/mysqld2.err 
:wq

]# mkdir  /dir2
]# mkdir  /dir1

启动多实例

首次启动服务会做数据初始化并初始和提示数据库管理员本机登录密码

[root@host57 ~]# mysqld_multi  start 1 //启动实例1
Installing new database in /dir1
2019-06-13T10:46:29.307866Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2019-06-13T10:46:30.997233Z 0 [Warning] InnoDB: New log files created, LSN=45790
2019-06-13T10:46:31.436904Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2019-06-13T10:46:31.582129Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 816bf015-8dc8-11e9-b492-525400cffedc.
2019-06-13T10:46:31.605276Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2019-06-13T10:46:31.606321Z 1 [Note] A temporary password is generated for root@localhost: ly#LryiFE5fT  管理员本机登录密码
]# ls /dir1 //查看数据库目录文件列表
auto.cnf  ib_buffer_pool  ibdata1  ib_logfile0  ib_logfile1  ibtmp1  mysql  mysql3307.log  mysql3307.pid  mysql3307.sock  mysql3307.sock.lock  performance_schema  sys
]# mysqld_multi  start 2  //启动实例2
Installing new database in /dir1
2019-06-13T10:56:55.580796Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2019-06-13T10:56:57.199217Z 0 [Warning] InnoDB: New log files created, LSN=45790
2019-06-13T10:56:57.571839Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2019-06-13T10:56:57.708168Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: f69f30fa-8dc9-11e9-8a17-525400cffedc.
2019-06-13T10:56:57.724096Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2019-06-13T10:56:57.724677Z 1 [Note] A temporary password is generated for root@localhost: qedTjrZs*8ma  管理员本机登录密码
]# ls /dir1 //查看数据库目录文件列表
auto.cnf  ib_buffer_pool  ibdata1  ib_logfile0  ib_logfile1  ibtmp1  mysql  mysql3308.log  mysql3308.pid  mysql3308.sock  mysql3308.sock.lock  performance_schema  sys

查看端口

]# netstat -utnlp  | grep :3307
tcp6       0      0 :::3307                 :::*                    LISTEN      1151/mysqld         
]# netstat -utnlp  | grep :3308
tcp6       0      0 :::3308                 :::*                    LISTEN      1339/mysqld         
]# netstat -utnlp | grep mysqld
tcp6       0      0 :::3307                 :::*                    LISTEN      1151/mysqld         
tcp6       0      0 :::3308                 :::*                    LISTEN      1339/mysqld         
# ps -C mysqld
  PID TTY          TIME CMD
 1151 pts/1    00:00:00 mysqld
 1339 pts/1    00:00:00 mysqld
[root@host57 ~]#

访问多实例

使用初始化密码登录实例1

[root@host57 ~]# mysql -uroot -p'ly#LryiFE5fT' -S /dir1/mysqld1.sock 
    mysql> alter user root@"localhost" identified by "123456";    //修改密码
mysql> exit
Bye
[root@host57 ~]# mysql -uroot -p123456  -S /dir1/mysqld1.sock //新密码登录
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 4
Server version: 5.7.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2017, 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> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)
mysql> create database db1; //创建新库db1
Query OK, 1 row affected (0.00 sec)
mysql> show databases; //查看已有的库
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |  //db1库
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)
mysql> exit  //断开连接
Bye
[root@host56 ~]# ls /dir1  //查看数据库目录文件列表 有db1库的文件夹
auto.cnf        ibdata1      ibtmp1       mysqld1.pid          performance_schema
db1             ib_logfile0  mysql        mysqld1.socket       sys
ib_buffer_pool  ib_logfile1  mysqld1.err  mysqld1.socket.lock
[root@host56 ~]#

使用初始化密码登录实例2

[root@host57 ~]# mysql -uroot -p'qedTjrZs*8ma' -S /dir2/mysqld2.sock 
    mysql> alter user root@"localhost" identified by "654321";    //修改密码
mysql> exit
Bye
[root@host57 ~]# mysql -uroot –p654321  -S /dir2/mysqld2.sock //新密码登录
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 4
Server version: 5.7.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2017, 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> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)
mysql>
mysql> create database db2;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db2                |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)
mysql> exit
Bye
[root@host56 ~]# ls /dir2
auto.cnf        ib_logfile0  mysqld2.err          performance_schema
db2             ib_logfile1  mysqld2.pid          sys
ib_buffer_pool  ibtmp1       mysqld2.socket
ibdata1         mysql        mysqld2.socket.lock
[root@host56 ~]#

停止多实例服务

mysqld_multi --user=root --password=密码 stop 实例编号

    ]# netstat -utnlp  | grep  mysqld
    tcp6       0      0 :::3307                 :::*                    LISTEN      1250/mysql
    tcp6       0      0 :::3308                 :::*                    LISTEN      1451/mysql
    ]# mysqld_multi  --user=root --password=123456  stop 2
     [root@host56 ~]# netstat -utnlp  | grep  mysqld
    tcp6       0      0 :::3307                 :::*                    LISTEN      1250/mysql
    ]# mysql -uroot   -p123456   -S    /dir2/mysqld2.sock //拒绝连接
    mysql: [Warning] Using a password on the command line interface can be insecure.
    ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/dir2/mysqld2.sock' (2)