mysql主从——传统配置

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已于 2022-07-04 20:13:35 修改

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文章标签：数据库大数据

于 2022-07-03 20:57:25 首次发布

本文链接：https://blog.youkuaiyun.com/qq_59324730/article/details/125588266

本文介绍了一种典型的MySQL主从复制配置方案，包括环境准备、数据同步、账号授权及配置等关键步骤。通过实例演示了如何搭建稳定的主从架构，确保数据的高可用性和一致性。

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使用主从的原因：

用一台数据库存放数据，若此数据库服务器宕机了导致数据丢失怎么办？
业务量大了，数据多了，访问的人多了，一台数据库无法保证服务质量了怎么办？

主从的作用：

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

主从形式

一主一从
主主复制
一主多从---扩展系统读取的性能，因为读是在从库读取的
多主一从---5.7开始支持
联级复制

主从复制原理

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

1 主从复制配置（传统主从配置）

主从复制配置步骤：

确保从数据库与主数据库里的数据一样
在主数据库里创建一个同步账号授权给从数据库使用
配置主数据库（修改配置文件）
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	192.168.31.129	centos8/redhat8 mysql-5.7	有数据
从数据库	192.168.31.131	centos8/redhat8 mysql-5.7	无数据

1.1 mysql安装

1.2主从配置

1.2.1 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里的数据一样，先全备主数据库并还原到从数据库中

主库192.168.31.129
从库192.168.31.131
//先查看主库有哪些库
[root@localhost ~]# mysql -uroot -p'123456'
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

//再查看从库有哪些库
[root@localhost ~]# mysql -uroot -p'ltt429520.' -h127.0.0.1 -P3306
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

//全备主库
//全备主库时需要另开一个终端，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 (0.00 sec)
//此锁表的终端必须在备份完成以后才能退出

//备份主库并将备份文件传送到从库
[root@localhost ~]# mysqldump -uroot -p123456 --all-databases > /opt/all-$(date '+%Y%m%d%H%M%S').sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# ls /opt/
all-20220703201201.sql  data
[root@localhost ~]# scp /opt/all-20220703201201.sql root@192.168.31.131:/opt/
The authenticity of host '192.168.31.131 (192.168.31.131)' can't be established.
ECDSA key fingerprint is SHA256:SnDB0Bvu9G0De5LWH0eKRgDOaZghNQ1WABlU049ZEew.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.31.131' (ECDSA) to the list of known hosts.
root@192.168.31.131's password: 
all-20220703201201.sql          100%  854KB 101.6MB/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

//在从库上恢复主库的备份并查看从库有哪些库，确保与主库一致
[root@localhost ~]# mysql -uroot -p'ltt429520.' -h127.0.0.1 -P3306 < /opt/all-20220703201201.sql 
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# mysql -uroot -p'ltt429520.' -h127.0.0.1 -P3306
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: 5.7.37 MySQL Community Server (GPL)

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

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)

1.2.2 在主数据库里创建一个同步账号授权给从数据库使用

mysql> grant replication slave on *.* to 'repl'@'192.168.31.131' i
dentified by 'repl123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)   //从主机的ip

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

1.2.3 配置主数据库

[root@localhost ~]# vim /etc/my.cnf 
[root@localhost ~]# cat /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 = 10         //添加。主库的server-id值必须比从库的小
log-bin = mysql_bin
//重启
[root@localhost ~]# systemctl restart mysqld
[root@localhost ~]# systemctl status mysqld
● mysqld.service - mysql server daemon
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enable>
   Active: active (running) since Sun 2022-07-03 20:25:21 CST; 18>
  Process: 1883 ExecStop=/usr/local/mysql/support-files/mysqld st>
  Process: 1910 ExecStart=/usr/local/mysql/support-files/mysqld s>
 Main PID: 1924 (mysqld_safe)
    Tasks: 28 (limit: 11216)
   Memory: 181.6M
   CGroup: /system.slice/mysqld.service
           ├─1924 /bin/sh /usr/local/mysql/bin/mysqld_safe --data>
           └─2138 /usr/local/mysql/bin/mysqld --basedir=/usr/loca>

Jul 03 20:25:20 localhost.localdomain systemd[1]: mysqld.service:>
Jul 03 20:25:20 localhost.localdomain systemd[1]: Stopped mysql s>
Jul 03 20:25:20 localhost.localdomain systemd[1]: Starting mysql >
Jul 03 20:25:21 localhost.localdomain mysqld[1910]: Starting MySQ>
Jul 03 20:25:21 localhost.localdomain systemd[1]: Started mysql s>
[root@localhost ~]# 

//查看主库的状态
[root@localhost ~]# mysql -uroot -p'123456'
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql_bin.000001 |      154 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

1.2.4 配置从数据库

[root@localhost ~]# vim /etc/my.cnf 
[root@localhost ~]# cat /etc/my.cnf 
[mysqld_multi]
mysqld = /usr/local/mysql/bin/mysqld_safe
mysqladmin = /usr/local/mysql/bin/mysqladmin

[mysqld3306]
datadir = /opt/data/3306
port = 3306
socket = /tmp/mysql3306.sock
pid-file = /opt/data/3306/mysql_3306.pid
log-error=/var/log/3306.log

server-id = 20
relay-log = myrelay

//重启
[root@localhost ~]# systemctl restart my3306
[root@localhost ~]# systemctl status my3306
● my3306.service - 3306 server daemon
   Loaded: loaded (/usr/lib/systemd/system/my3306.service; enable>
   Active: active (running) since Sun 2022-07-03 20:33:25 CST; 12>
  Process: 4339 ExecStop=/usr/bin/ps -ef|grep 3306|grep -v grep|a>
  Process: 4346 ExecStart=/usr/local/mysql/bin/mysqld_multi start>
 Main PID: 4352 (mysqld_safe)
    Tasks: 28 (limit: 11088)
   Memory: 186.8M
   CGroup: /system.slice/my3306.service
           ├─4352 /bin/sh /usr/local/mysql/bin/mysqld_safe --data>
           └─4516 /usr/local/mysql/bin/mysqld --basedir=/usr/loca>

Jul 03 20:33:25 localhost.localdomain systemd[1]: my3306.service:>
Jul 03 20:33:25 localhost.localdomain systemd[1]: Stopped 3306 se>
Jul 03 20:33:25 localhost.localdomain systemd[1]: Starting 3306 s>
Jul 03 20:33:25 localhost.localdomain systemd[1]: Started 3306 se>
[root@localhost ~]# 

//防火墙关掉
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# getenforce
Disabled
[root@localhost ~]# systemctl disable --now firewalld

//配置并启动主从复制
mysql> change master to
    -> master_host='192.168.31.129',
    -> master_user='repl',
    -> master_password='repl123!',
    -> master_port=3306,
    -> master_log_pos='mysql_bin.000001',
    -> mysql_log_poss=154;
mysql> start slave;

//查看从服务器状态
mysql> show slave status \G
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes      //此处必须为Yes
            Slave_SQL_Running: Yes      //此处必须为Yes
              Replicate_Do_DB:
          Replicate_Ignore_DB:

1.2.5 测试验证

在主服务器的student库的ltt1表中插入数据：

mysql> select * from ltt1;
Empty set (0.00 sec)

mysql> insert into ltt1 values (1,'sean',20),(2,'tom',23),(3,'jerry',30);
Query OK, 3 rows affected (0.00 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select * from ltt1;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | sean  |   20 |
|  2 | tom   |   23 |
|  3 | jerry |   30 |
+----+-------+------+
3 rows in set (0.00 sec)

在从数据库中查看数据是否同步：

mysql> use student;
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 ltt1;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | sean  |   20 |
|  2 | tom   |   23 |
|  3 | jerry |   30 |
+----+-------+------+
3 rows in set (0.00 sec)