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mysql主从

由 我与影子孤独终老i 提交于 2019-11-28 01:15:29

mysql主从

1. 主从简介

1.1主从作用

  • 实时灾备，用于故障切换
  • 读写分离，提供查询服务
  • 备份，避免影响业务

1.2主从形式

  • 一主一从
  • 主主复制—设置互斥
  • 一主多从—扩展系统读取性能，因为读是从库读取的
  • 多主一从—5.7开始支持
  • 联级复制
    如下图所示：
    在这里插入图片描述

2. 主从复制原理

在这里插入图片描述
主从复制步骤：

  • 主库将所有的写操作记录到binlog日志中并生成一个log dump线程，将binlog日志传给从库的I/O线程
  • 从库生成两个线程，一个I/O线程，一个SQL线程
  • I/O线程去请求主库的binlog,并将得到的binlog日志写到relay log(中继日志)文件中
  • SQL线程，会读取relay log文件中的日志，并解析成具体操作，来实现主从的操作一致，达到最终数据一致的目的

3. 主从复制配置

主从复制配置步骤：

  1. 确保从数据库和主数据库的数据一样
  2. 在主数据库里创建一个同步账号授权给数据库使用
  3. 配置主数据库（修改配置文件）
  4. 配置从数据库（修改配置文件）

需求：
搭建两台MySQL服务器，一台作为主服务器，一台作为从服务器，主服务器进行写操作，从服务器进行读操作

环境说明：

数据库角色 IP 应用与系统版本 有无数据
主数据库 192.168.176.111 centos7/redhat7
mysql-5.7		 有数据
从数据库 192.168.176.112 centos7/redhat7
mysql-5.7		 无数据

3.1mysql安装

分别在主从两台服务器上安装mysql-5.7版本，此处略过安装步骤，若有疑问请参考MySQL基础和MySQL进阶两篇文章

3.2mysql主从配置

3.2.1确保从数据库与主数据库里的数据一样

为确保从数据库与主数据库的数据一样，先全备主数据库并还原到从数据库中

//先查看主库有哪些库
[root@lwq-mysql ~]# mysql -uroot -plwq -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| liuwanqian         |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

//再查看从库有哪些库
[root@lwq-client ~]# mysql -uroot -plwq -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+


//全备主库
//全被主库时需开另一个终端，给数据库加上读锁，避免在备份期间有其他人在写入导致数据不一致
mysql> flush tables with read lock;
Query OK, 0 rows affected (0.68 sec)
//此锁表的终端必须在备份完成后才能退出

//备份主库并将备份文件传送到从库
[root@lwq-mysql ~]# mysqldump -uroot -plwq --all-databases > all-20190819.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@lwq-mysql ~]# ls
all-20190819.sql
[root@lwq-mysql ~]# scp all-20190819.sql root@192.168.176.112:/root/
The authenticity of host '192.168.176.112 (192.168.176.112)' can't be established.
ECDSA key fingerprint is SHA256:acbRY/PG8nam4qE6Fue8SlFyxibg2xiUSLulWkR4nKM.
ECDSA key fingerprint is MD5:7c:b8:ac:81:bc:3f:d4:76:06:a9:09:d4:0f:76:2a:6c.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.176.112' (ECDSA) to the list of known hosts.
root@192.168.176.112's password: 
all-20190819.sql                                         100%  783KB  23.7MB/s   00:00 

//解除主库的锁表状态，直接退出交互式界面即可
mysql> quit
Bye

//在从库上恢复主库并查看从库有哪些文件，确保与主库一致
[root@lwq-client ~]# ls
all-20190819.sql 
[root@lwq-client ~]# mysql -uroot -plwq -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
[root@lwq-client ~]# mysql -uroot -plwq < all-20190819.sql 
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@lwq-client ~]# mysql -uroot -plwq -e 'show databases;'
mysql: [Warning] Using a password on the command line interface can be insecure.
+--------------------+
| Database           |
+--------------------+
| information_schema |
| liuwanqian         |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

3.2.2在主数据库里创建一个同步账号授权给从数据库使用

mysql> create user 'lwq'@'192.168.176.112' identified by 'lwq123';
Query OK, 0 rows affected (0.01 sec)

mysql> grant replication slave on *.* to 'lwq'@'192.168.176.112';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

3.2.3配置主数据库

[root@lwq-mysql ~]# vim /etc/my.cnf
[root@lwq-mysql ~]# cat /etc/my.cnf      //添加以下内容
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
pid-file = /opt/data/mysql.pid
user = mysql
skip-name-resolve

log-bin = mysql-bin              //启用binlog日志
server-id = 1                        //数据库服务器唯一标识符，主库的server-id值必须比从库小，值越小优先级越高

//重启mysql服务并查看mysql端口号
[root@lwq-mysql ~]# systemctl restart mysqld
[root@lwq-mysql ~]# ss -antl

//查看主库的状态
mysql> show master status;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    2
Current database: *** NONE ***

+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000002 |      154 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

3.2.4配置从数据库

[root@lwq-client ~]# vim /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
pid-file = /opt/data/mysql.pid
user = mysql
skip-name-resolve

server-id = 2               //设置从库的唯一标识符，从库的server-id值必须大于主库的该值
relay-log = mysql-relay-bin    //启用中继日志relay-log


//二进制安装的mysql用绝对路径启动该服务
[root@lwq-client ~]# /etc/init.d/mysqld restart
Shutting down MySQL.... SUCCESS! 
Starting MySQL............... SUCCESS! 
[root@lwq-client ~]# ss -antl
State       Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN      0      128               *:111                           *:*                  
LISTEN      0      5      192.168.122.1:53                            *:*                  
LISTEN      0      128               *:22                            *:*                  
LISTEN      0      128       127.0.0.1:631                           *:*                  
LISTEN      0      100       127.0.0.1:25                            *:*                  
LISTEN      0      128       127.0.0.1:6010                          *:*                  
LISTEN      0      128       127.0.0.1:6011                          *:*                  
LISTEN      0      128              :::111                          :::*                  
LISTEN      0      128              :::22                           :::*                  
LISTEN      0      128             ::1:631                          :::*                  
LISTEN      0      100             ::1:25                           :::*                  
LISTEN      0      128             ::1:6010                         :::*                  
LISTEN      0      128             ::1:6011                         :::*                  
LISTEN      0      80               :::3306                         :::*    

//配置并启动主从复制
[root@lwq-client ~]# mysql -uroot -plwq
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: 5.7.22 MySQL Community Server (GPL)

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> change master to
    -> master_host='192.168.176.111',
    -> master_user='lwq',
    -> master_password='lwq123',
    -> master_log_file='mysql-bin.000002',
    -> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.05 sec)

mysql> start slave;
Query OK, 0 rows affected (0.04 sec)

//查看从服务器状态
mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.176.111
                  Master_User: lwq
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 154
               Relay_Log_File: mysql-relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000002
             Slave_IO_Running: Yes          //此处必须为yes 
            Slave_SQL_Running: Yes        //此处必须为yes

3.2.5测试验证

在主服务器的liuwanqian库的studnet表中插入数据：

mysql> use liuwanqian;
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 student;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  1 | tom         |   20 |
|  2 | jerry       |   23 |
|  3 | wangqing    |   25 |
|  4 | sean        |   28 |
|  5 | zhangshan   |   26 |
|  6 | zhangshan   |   20 |
|  7 | lisi        | NULL |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
| 10 | qiuyi       |   15 |
| 11 | qiuxiaotian |   20 |
+----+-------------+------+
11 rows in set (0.00 sec)

mysql> insert into student(name,age) values('xixi',10),('haha',11);
Query OK, 2 rows affected (0.02 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> select * from student;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  1 | tom         |   20 |
|  2 | jerry       |   23 |
|  3 | wangqing    |   25 |
|  4 | sean        |   28 |
|  5 | zhangshan   |   26 |
|  6 | zhangshan   |   20 |
|  7 | lisi        | NULL |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
| 10 | qiuyi       |   15 |
| 11 | qiuxiaotian |   20 |
| 12 | xixi        |   10 |
| 13 | haha        |   11 |
+----+-------------+------+
13 rows in set (0.00 sec)

在从数据库中查看数据是否同步：

mysql> use liuwanqian;
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 student;
+----+-------------+------+
| id | name        | age  |
+----+-------------+------+
|  1 | tom         |   20 |
|  2 | jerry       |   23 |
|  3 | wangqing    |   25 |
|  4 | sean        |   28 |
|  5 | zhangshan   |   26 |
|  6 | zhangshan   |   20 |
|  7 | lisi        | NULL |
|  8 | chenshuo    |   10 |
|  9 | wangwu      |    3 |
| 10 | qiuyi       |   15 |
| 11 | qiuxiaotian |   20 |
| 12 | xixi        |   10 |
| 13 | haha        |   11 |
+----+-------------+------+
13 rows in set (0.00 sec)
//增加了两条新内容，验证成功！
标签
mysql
mysql创建数据库
mysql主从配置
mysql读写分离
log
master
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