MySQL主从

文章目录

MySQL主从
- - 一. 主从介绍

一. 主从介绍

MySQL主从又叫做Replication、AB复制。简单讲就是A和B两台机器做主从后，在A上写数据，另外一台B也会跟着写数据，两者数据实时同步的

1. 作用

实时灾备，用于故障切换
- 某一台主机发生故障另外一台可以替换
读写分离，提供查询服务
备份，避免影响业务
- 它备份的是服务器，实例

2. 主从形式，Master-Slave

一主一从，写操作比较少，读操作比较多，（例京东）
主主复制，数据同步，使用共享存储
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，在写操作比较多，读操作比较少，（例12306购票）
联级复制

在这里插入图片描述

3. 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（硬盘）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

在这里插入图片描述

主，将所有写操作记录到binlog日志
从，I/O

4. 主从复制配置

4.1 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）

4.2 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

4.3 环境

数据库角色	IP	应用与系统版本	有无数据
主数据库	192.168.232.134	Red Hat Enterprise Linux release 8.5 (Ootpa) mysql-5.7	有数据
从数据库	192.168.232.128	Red Hat Enterprise Linux release 8.5 (Ootpa) mysql-5.7	无数据

5. 先创建主数据

134
mysql> create database school;
Query OK, 1 row affected (0.01 sec)

mysql> use school;
Database changed
mysql> create table tb_student_info(id int not null primary key auto_increment,name varchar(30),age tinyint,sex varchar(6),height
int,course_id int);
Query OK, 0 rows affected (0.13 sec)

mysql> insert into tb_student_info(name,age,sex,height,course_id) values('danny',25,'M',160,1),('green',23,'M',158,2),('henry',23,'F',185,1),('jane',23,'M',162,3),('jim',22,'F',175,2),('john',21,'F',172,4),('lily',22,'M',165,4),('susan',23,'M',170,5),('thomas',22,'F',178,5),('tom',23,'F',165,5);
Query OK, 10 rows affected (0.13 sec)
Records: 10  Duplicates: 0  Warnings: 0
mysql> select * from tb_student_info;
+----+--------+------+------+--------+-----------+
| id | name   | age  | sex  | height | course_id |
+----+--------+------+------+--------+-----------+
|  1 | danny  |   25 | M    |    160 |         1 |
|  2 | green  |   23 | M    |    158 |         2 |
|  3 | henry  |   23 | F    |    185 |         1 |
|  4 | jane   |   23 | M    |    162 |         3 |
|  5 | jim    |   22 | F    |    175 |         2 |
|  6 | john   |   21 | F    |    172 |         4 |
|  7 | lily   |   22 | M    |    165 |         4 |
|  8 | susan  |   23 | M    |    170 |         5 |
|  9 | thomas |   22 | F    |    178 |         5 |
| 10 | tom    |   23 | F    |    165 |         5 |
+----+--------+------+------+--------+-----------+
10 rows in set (0.00 sec)

mysql> 
mysql> create table tb_coursse(id int not null primary key auto_increment,course_name varchar(30));
Query OK, 0 rows affected (0.17 sec)

mysql> insert into tb_coursse(course_name) values('java'),('mysql'),('python'),('go'),('c++');
Query OK, 5 rows affected (0.10 sec)
Records: 5  Duplicates: 0  Warnings: 0

mysql> select * from tb_coursse;
+----+-------------+
| id | course_name |
+----+-------------+
|  1 | java        |
|  2 | mysql       |
|  3 | python      |
|  4 | go          |
|  5 | c++         |
+----+-------------+
5 rows in set (0.00 sec)

mysql>

6. mysql主从配置

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134
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| school             |
| sys                |
+--------------------+
5 rows in set (0.01 sec)

mysql> 
从库128
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

mysql>

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)

mysql> 
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@134h ~]# mysqldump -uroot -prun123456 --all-databases > all-$(date '+%Y%m%d%H%M%S').mysql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@134h ~]# ls
all-20220702184959.mysql  anaconda-ks.cfg  pass
[root@134h ~]#

备份主库并将备份文件传送到从库

[root@134h ~]# ls
all-20220702184959.mysql  anaconda-ks.cfg  pass
[root@134h ~]# scp all-20220702184959.mysql root@192.168.232.128:/root/
The authenticity of host '192.168.232.128 (192.168.232.128)' can't be established.
ECDSA key fingerprint is SHA256:K5PZWAGixN2F0s4CX9AnYLG7WeRbA6adXzDLI4JRIpQ.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.232.128' (ECDSA) to the list of known hosts.
root@192.168.232.128's password: 
all-20220702184959.mysql       100%  857KB  13.7MB/s   00:00    
[root@134h ~]# 

[root@128m ~]# ls
3306.pass  3308.pass                 anaconda-ks.cfg
3307.pass  all-20220702184959.mysql
[root@128m ~]#

解除主库的锁表状态，直接退出交互式界面即可

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)

mysql> quit
Bye
[root@134h ~]#

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@128m ~]# ls
3306.pass  3308.pass                 anaconda-ks.cfg
3307.pass  all-20220702184959.mysql
[root@128m ~]# mysql -uroot -prun123456 -S /tmp/mysql3306.sock < all-20220702184959.mysql 
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@128m ~]# 

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

mysql>

6.1 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 'repl'@'192.168.232.128' identified by 'repl123';

Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> grant replication slave on *.* to 'repl'@'192.168.232.128';
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

6.2 配置主数据库

[root@134h ~]# vim /etc/my.cnf 
[root@134h ~]# 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 
sql-mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

server-id = 10 数据库服务器唯一标识符，主库的server-id值必须比从库的小
log-bin = mysql_bin //启用binlog日志
[root@134h ~]# 

重启mysql服务
[root@134h ~]# systemctl restart mysqld
[root@134h ~]# systemctl status mysqld
● mysqld.service - mysql server daemon
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabl>
   Active: active (running) since Sat 2022-07-02 22:07:46 CST; 4>
  Process: 1315650 ExecStop=/usr/local/mysql/support-files/mysql>
  Process: 1315981 ExecStart=/usr/local/mysql/support-files/mysq>
 Main PID: 1315995 (mysqld_safe)
    Tasks: 28 (limit: 23502)
   Memory: 180.8M
   CGroup: /system.slice/mysqld.service
           ├─1315995 /bin/sh /usr/local/mysql/bin/mysqld_safe -->
           └─1316221 /usr/local/mysql/bin/mysqld --basedir=/usr/>

Jul 02 22:07:45 134h.example.com systemd[1]: mysqld.service: Suc>
Jul 02 22:07:45 134h.example.com systemd[1]: Stopped mysql serve>
Jul 02 22:07:45 134h.example.com systemd[1]: Starting mysql serv>
Jul 02 22:07:46 134h.example.com mysqld[1315981]: Starting MySQL>
Jul 02 22:07:46 134h.example.com systemd[1]: Started mysql serve>
[root@134h ~]# 

进入
[root@134h ~]# mysql -uroot -prun123456
查看
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql_bin.000002 |      154 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql>

7. 配置从数据库

[root@128m ~]# vim /etc/my.cnf 
[root@128m ~]# 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


[mysqld3307]
datadir = /opt/data/3307
port = 3307
socket = /tmp/mysql3307.sock
pid-file = /opt/data/3307/mysql_3307.pid
log-error = /var/log/3307.log

[mysqld3308]
datadir = /opt/data/3308
port = 3308
socket = /tmp/mysql3308.sock
pid-file = /opt/data/3308/mysql_3308.pid
log-error = /var/log/3308.log
[root@128m ~]# 

重启从库
[root@128m ~]# systemctl restart sql3306
[root@128m ~]# systemctl status sql3306
* sql3306.service - 3306 server daemon
   Loaded: loaded (/usr/lib/systemd/system/sql3306.service; enab>
   Active: active (running) since Sat 2022-07-02 22:13:26 CST; 7>
  Process: 860294 ExecStop=/usr/bin/ps -ef|grep 3306|grep -v gre>
  Process: 860472 ExecStart=/usr/local/mysql/bin/mysqld_multi st>
 Main PID: 860478 (mysqld_safe)
    Tasks: 28 (limit: 23502)
   Memory: 182.0M
   CGroup: /system.slice/sql3306.service
           |-860478 /bin/sh /usr/local/mysql/bin/mysqld_safe --d>
           `-860642 /usr/local/mysql/bin/mysqld --basedir=/usr/l>

Jul 02 22:13:25 128m systemd[1]: Starting 3306 server daemon...
Jul 02 22:13:26 128m systemd[1]: Started 3306 server daemon.
[root@128m ~]#

7.1 配置并启动主从复制

mysql> change master to
    -> master_host='192.168.232.134',
    -> master_user='repl',
    -> master_password='repl123',
    -> master_log_file='mysql_bin.000002',
    -> master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.13 sec)

mysql> start slave;
Query OK, 0 rows affected (0.10 sec)

mysql>

7.2 查看从服务器状态

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: 192.168.232.128
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000002
          Read_Master_Log_Pos: 154
               Relay_Log_File: myrelay.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql_bin.000002
Slave_IO_Running: Connecting   Yes//此处必须为Yes
            Slave_SQL_Running: Yes//此处必须为Yes
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 


关闭防火墙
[root@128m ~]# systemctl disable --now firewalld
[root@128m ~]# systemctl stop firewalld
[root@128m ~]# systemctl status firewalld
* firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; di>
   Active: inactive (dead)
     Docs: man:firewalld(1)

  
再次查看
mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.232.134
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000002
          Read_Master_Log_Pos: 154
               Relay_Log_File: myrelay.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql_bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes//生效

8. 验证

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

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

mysql>

8.1 在主库上使用，增删改

主库，删除
mysql> drop database school;
Query OK, 2 rows affected (0.25 sec)

mysql> 

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

mysql> 

主库，创建
mysql> create database school;
Query OK, 1 row affected (0.00 sec)

mysql> use school;
Database changed
mysql> create table tb_student_info(id int not null primary key auto_increment,name varchar(30),age tinyint,sex varchar(6),height int,course_id int);
Query OK, 0 rows affected (0.13 sec)

mysql> insert into tb_student_info(name,age,sex,height,course_id) values('danny',25,'M',160,1),('green',23,'M',158,2),('henry',23,'F',185,1),('jane',23,'M',162,3),('jim',22,'F',175,2),('john',21,'F',172,4),('lily',22,'M',165,4),('susan',23,'M',170,5),('thomas',22,'F',178,5),('tom',23,'F',165,5);
Query OK, 10 rows affected (0.11 sec)
Records: 10  Duplicates: 0  Warnings: 0

mysql> 

从库
mysql> use school;
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> show tables;
+------------------+
| Tables_in_school |
+------------------+
| tb_student_info  |
+------------------+
1 row in set (0.00 sec)

mysql> select * from tb_student_info;
+----+--------+------+------+--------+-----------+
| id | name   | age  | sex  | height | course_id |
+----+--------+------+------+--------+-----------+
|  1 | danny  |   25 | M    |    160 |         1 |
|  2 | green  |   23 | M    |    158 |         2 |
|  3 | henry  |   23 | F    |    185 |         1 |
|  4 | jane   |   23 | M    |    162 |         3 |
|  5 | jim    |   22 | F    |    175 |         2 |
|  6 | john   |   21 | F    |    172 |         4 |
|  7 | lily   |   22 | M    |    165 |         4 |
|  8 | susan  |   23 | M    |    170 |         5 |
|  9 | thomas |   22 | F    |    178 |         5 |
| 10 | tom    |   23 | F    |    165 |         5 |
+----+--------+------+------+--------+-----------+
10 rows in set (0.00 sec)

mysql> 

主库，修改
mysql> update tb_student_info set height = 177 where name = 'green';
Query OK, 1 row affected (0.15 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> update tb_student_info set age = 26 where name = 'lily';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

从库
mysql> select * from tb_student_info;
+----+--------+------+------+--------+-----------+
| id | name   | age  | sex  | height | course_id |
+----+--------+------+------+--------+-----------+
|  1 | danny  |   25 | M    |    160 |         1 |
|  2 | green  |   23 | M    |    177 |         2 |
|  3 | henry  |   23 | F    |    185 |         1 |
|  4 | jane   |   23 | M    |    162 |         3 |
|  5 | jim    |   22 | F    |    175 |         2 |
|  6 | john   |   21 | F    |    172 |         4 |
|  7 | lily   |   26 | M    |    165 |         4 |
|  8 | susan  |   23 | M    |    170 |         5 |
|  9 | thomas |   22 | F    |    178 |         5 |
| 10 | tom    |   23 | F    |    165 |         5 |
+----+--------+------+------+--------+-----------+
10 rows in set (0.00 sec)

                
主库，删除
mysql> delete from tb_student_info where name = 'john';
Query OK, 1 row affected (0.00 sec)

mysql> delete from tb_student_info where name = 'thomas';
Query OK, 1 row affected (0.00 sec)

mysql> 
                
                
从库
mysql> select * from tb_student_info;
+----+-------+------+------+--------+-----------+
| id | name  | age  | sex  | height | course_id |
+----+-------+------+------+--------+-----------+
|  1 | danny |   25 | M    |    160 |         1 |
|  2 | green |   23 | M    |    177 |         2 |
|  3 | henry |   23 | F    |    185 |         1 |
|  4 | jane  |   23 | M    |    162 |         3 |
|  5 | jim   |   22 | F    |    175 |         2 |
|  7 | lily  |   26 | M    |    165 |         4 |
|  8 | susan |   23 | M    |    170 |         5 |
| 10 | tom   |   23 | F    |    165 |         5 |
+----+-------+------+------+--------+-----------+
8 rows in set (0.00 sec)