MySQL：一主两从架构

1. 主从同步原理

1.1 基本原理

slave会从master读取binlog来进行数据同步

1.2 具体步骤

• (1): master将数据改变记录到二进制日志binlog中；
• (2): slave上执行start slave命令后，slave会创建一个IO线程，用来连接master，请求master中的binlog;
• (3): 当slave连接master时，master会创建一个log dump线程，用于发送binlog内容。在读取binlog的内容的操作中，会对主节点上的binlog加锁，当读取完成并发送给从服务器后解锁；
• (4): IO线程接受主节点发送过来的更新后，保存到中继日志relay log中；
• (5): slave的SQL线程，读取relay log日志，并解析成具体操作，从而实现主从操作一致，最终数据一致。

2. 开始一主两从配置

2.1 服务器规划

2.2 环境需要

1. docker
2. 防火墙关闭

#关闭docker
systemctl stop docker
#关闭防火墙
systemctl stop firewalld
#启动docker
systemctl start docker
1
2
3
4
5
6

2.3 配置master

1. docker拉取mysql 5.7镜像

docker pull mysql:5.7
1

2. docker创建并启动master

docker run -d \
-p 3306:3306 \
-v /atguigu/mysql/master/conf:/etc/mysql/conf.d \
-v /atguigu/mysql/master/data:/var/lib/mysql \
-e MYSQL_ROOT_PASSWORD=123456 \
--name atguigu-mysql-master \
mysql:5.7
1
2
3
4
5
6
7

3. 创建MySQL主服务器配置文件

vim /atguigu/mysql/master/conf/my.cnf
1

写入如下内容

[mysqld]
# 服务器唯一id，默认值1
server-id=1
# 设置日志格式，默认值ROW
binlog_format=STATEMENT
# 二进制日志名，默认binlog
log-bin=binlog
1
2
3
4
5
6
7

4. 重启master节点

docker restart atguigu-mysql-master
1

5. 进入master节点内部

#进入容器：env LANG=C.UTF-8 避免容器中显示中文乱码
docker exec -it atguigu-mysql-master env LANG=C.UTF-8 /bin/bash
#进入容器内的mysql命令行
mysql -uroot -p
#修改默认密码校验方式
ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';
1
2
3
4
5
6

6. master中创建slave用户

-- 创建slave用户
CREATE USER 'atguigu_slave'@'%';
-- 设置密码
ALTER USER 'atguigu_slave'@'%' IDENTIFIED WITH mysql_native_password BY '123456';
-- 授予复制权限
GRANT REPLICATION SLAVE ON *.* TO 'atguigu_slave'@'%';
-- 刷新权限
FLUSH PRIVILEGES;
1
2
3
4
5
6
7
8

7. 查看master状态

mysql> show master status;
+---------------+----------+--------------+------------------+-------------------+
| File          | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+---------------+----------+--------------+------------------+-------------------+
| binlog.000001 |     3740 |              |                  |                   |
+---------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
1
2
3
4
5
6
7

记下File和Position的值。执行完此步骤后不要再操作主服务器MYSQL，防止主服务器状态值变化。

2.4 配置slave1

1. docker启动slave1

docker run -d \
-p 3307:3306 \
-v /atguigu/mysql/slave1/conf:/etc/mysql/conf.d \
-v /atguigu/mysql/slave1/data:/var/lib/mysql \
-e MYSQL_ROOT_PASSWORD=123456 \
--name atguigu-mysql-slave1 \
mysql:5.7
1
2
3
4
5
6
7

2. 创建mysql从服务器配置文件

vim /atguigu/mysql/slave1/conf/my.cnf
1

写入如下内容

[mysqld]
# 服务器唯一id，每台服务器的id必须不同，如果配置其他从机，注意修改id
server-id=2
# 中继日志名，默认xxxxxxxxxxxx-relay-bin
relay-log=relay-bin
# 设置普通用户为只读,该项如果不设置，表示普通用户slave可读可写
read_only=1
# 设置超级用户为只读,该项如果不设置，表示slave可读可写
super_read_only=1
# 指定要同步的数据库，必须的
replicate-do-db=testdb
1
2
3
4
5
6
7
8
9
10
11

3. 重启slave1

docker restart atguigu-mysql-slave1
1

4. 进入slave1节点内部

#进入容器：env LANG=C.UTF-8 避免容器中显示中文乱码
docker exec -it atguigu-mysql-slave1 env LANG=C.UTF-8 /bin/bash
#进入容器内的mysql命令行
mysql -uroot -p
#修改默认密码校验方式
ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';
1
2
3
4
5
6

5. 配置主从关系

CHANGE MASTER TO MASTER_HOST='xxx.xxx.xxx.xxx', 
MASTER_USER='atguigu_slave',MASTER_PASSWORD='123456', MASTER_PORT=3306,
MASTER_LOG_FILE='binlog.000001',MASTER_LOG_POS=3740; 
1
2
3

注意这里的MASTER_LOG_FILE与MASTER_LOG_POS是上面master的File和Position

6. 启动主从同步

START SLAVE;
1

7. 查看状态
   注意：Slave_IO_Running与Slave_SQL_Running两个线程都必须全为Yes，则说明主从配置成功！

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.24.10.198
                  Master_User: atguigu_slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: binlog.000001
          Read_Master_Log_Pos: 3740
               Relay_Log_File: relay-bin.000003
                Relay_Log_Pos: 3947
        Relay_Master_Log_File: binlog.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: testdb
          Replicate_Ignore_DB:
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 3740
              Relay_Log_Space: 4148
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File:
           Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
               Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Master_Server_Id: 1
                  Master_UUID: 00fee855-5058-11ed-b0c0-0242ac110002
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Master_SSL_Crl:
           Master_SSL_Crlpath:
           Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position: 0
         Replicate_Rewrite_DB:
                 Channel_Name:
           Master_TLS_Version:
1 row in set (0.00 sec)

ERROR:
No query specified
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63

2.5 配置slave2

步骤同slave1，注意修改配置文件中的server-id

3. 一些其它的命令

1. 查看只读开关
2. 查看通用日志开关或路径

mysql> show global variables like '%read_only%';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| innodb_read_only      | OFF   |
| read_only             | ON    |
| super_read_only       | ON    |
| transaction_read_only | OFF   |
| tx_read_only          | OFF   |
+-----------------------+-------+
5 rows in set (0.00 sec)

mysql> show variables like 'general_log%';
+------------------+---------------------------------+
| Variable_name    | Value                           |
+------------------+---------------------------------+
| general_log      | OFF                             |
| general_log_file | /var/lib/mysql/eb30519b4804.log |
+------------------+---------------------------------+
2 rows in set (0.00 sec)

mysql>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

4. SpringBoot实现

https://blog.csdn.net/qq_39198749/article/details/127577547?spm=1001.2014.3001.5502