MySQL主从复制之进阶延时同步、GTID复制、半同步复制完整实验流程

1.主从同步

1.1主从同步原理

是指将主库的DDL和DML操作通过二进制日志(binlog)传到从库服务器，然后在从库上对这些日志进行重新执行，从而使从库和主库数据保持一致

1.2环境设置

|----------------|----------------|---------|-----------------|
| 库名 | ip地址 | 操作系统 | mysql版本 |
| 主库msyql-master | 192.168.31.228 | rhel7.9 | 源码安装mysql8.0.40 |
| 从库mysql-slave1 | 192.168.31.229 | rhel7.9 | 源码安装mysql8.0.40 |

1.3定位主库

bash 复制代码

#定位主库

#编辑配置文件
[root@mysql-master ~]# vim /etc/my.cnf
[mysqld]
datadir=/data/mysql
socket=/data/mysql/mysql.sock
server_id=228     #每台服务器必须要唯一标识自己的id,可以使用ip尾号方便记忆
log-bin=binlog    #开启二进制日志

#启动msyql
[root@mysql-master ~]# /etc/init.d/mysqld start
Starting MySQL SUCCESS!

#进入mysql
[root@mysql-master ~]# mysql -uroot -p123
mysql> create user 'rep'@'%' identified by 'rep123';   #创建用于共享的账户并设置密码为rep123
Query OK, 0 rows affected (0.01 sec)
mysql> grant replication slave on *.* to 'rep'@'%';     #赋予rep账户复制权限
Query OK, 0 rows affected (0.00 sec)
mysql> flush tables with read lock;      #锁表设置只读，注意生产环境要提前申请停机时间
Query OK, 0 rows affected (0.00 sec)
mysql> create database andy;      #测试，创建数据库失败，锁表成功！
ERROR 1223 (HY000): Can't execute the query because you have a licting read lock
mysql> show master status\G;   #查看主库状态
*************************** 1. row ***************************
             File: binlog.000004       #二进制日志文件
         Position: 1053            #文件位置
     Binlog_Do_DB:  
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 
1 row in set (0.00 sec)

1.4定位从库

bash 复制代码

#定位从数据库

#编辑配置文件
[root@mysql-slave1 ~]# vim /etc/my.cnf
[mysqld]
datadir=/data/mysql
socket=/data/mysql/mysql.sock
server_id=229    #设置唯一id
log-bin=binlog

#因为此台从服务器是由主数据库克隆而来的，因此两台服务器具有相同的uuid,后续会出现错误，因此先停止mysql,删除/data/mysql目录下的所有文件，初始化。重启mysql,修改账户密码即可；具体如下操作；但是如果你的两台机子是单独创建的，可以不用进行如下操作，直接进入mysql即可
[root@mysql-slave1 ~]# /etc/init.d/mysqld stop   #停止mysql
 ERROR! MySQL server PID file could not be found!
[root@mysql-slave1 ~]# rm -rf /data/mysql/*    #删除/data/mysql目录下的所有文件
[root@mysql-slave1 ~]# mysqld --initialize --user=mysql   #初始化生成原始密码
2025-09-04T08:24:26.715327Z 0 [System] [MY-013169] [Server] /usr/local/mysql/bin/mysqld (mysqld 8.0.40) initializing of server in progress as process 2802
2025-09-04T08:24:26.731299Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2025-09-04T08:24:26.907524Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2025-09-04T08:24:27.443256Z 6 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: ,<aO>w<GF1xi    
[root@mysql-slave1 ~]# /etc/init.d/mysqld start   #重启mysql
Starting MySQL.Logging to '/data/mysql/mysql-slave1.err'.
. SUCCESS! 
[root@mysql-slave1 ~]# mysqladmin -uroot -p',<aO>w<GF1xi' password '123'  #修改密码
mysqladmin: [Warning] Using a password on the command line interface can be insecure.
Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.


#进入mysql
[root@mysql-slave1 ~]# mysql -uroot -p123
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 9
Server version: 8.0.40 Source distribution

Copyright (c) 2000, 2024, 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> change replication source to      #设置从库向主库同步
    -> source_host='192.168.31.228',      #主库ip
    -> source_user='rep',      #主库设置用于共享的账户名
    -> source_password='rep123',      #账户密码
    -> source_log_file='binlog.000004',     #二进制日志文件；MySQL主从复制是主库通过二进制日志将数据传送给从库
    -> source_log_pos=1053,    #日志文件位置
    -> source_ssl=1;           
Query OK, 0 rows affected, 2 warnings (0.01 sec)

mysql> start replica;     #启动同步
Query OK, 0 rows affected (0.13 sec)

mysql> show replica status\G;    #查看同步状态
Replica_IO_Running: Yes  
Replica_SQL_Running: Yes    #I/O线程、SQL线程已打开

1.5测试

bash 复制代码

#测试

#定位主库：
mysql> create database andy;
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| andy               |
+--------------------+
5 rows in set (0.00 sec)


#定位从库：
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |   
| andy                 |    #出现andy数据库，同步成功
+--------------------+
5 rows in set (0.00 sec)

2.延时同步

2.1延时同步原理

通过人为配置从库和主库延时N小时可以实现延时同步，延时同步可以解决数据库故障出现的数据丢失问题。基于上述实验进行！

2.2定位从库-关闭同步、设置延迟时间、开启同步

bash 复制代码

#定位从库

mysql> stop replica;    #停止同步
Query OK, 0 rows affected (0.01 sec)
  
mysql> change replication source to source_delay=300;  #设置SQL线程延时300s后读取relay log
Query OK, 0 rows affected (0.01 sec)

mysql> start replica;     #开启同步
Query OK, 0 rows affected (0.14 sec)

mysql> show replica status\G;   #查看同步状态
SQL_Delay: 300    #延迟时间300s
SQL_Remaining_Delay: NULL   #在主库未进行操作，保留延迟为空

2.3定位主库-创建库、表、插入数据、误删库

bash 复制代码

#定位主库

mysql> create database relay;   #创建relay账户
Query OK, 1 row affected (0.00 sec)

#如果创建失败，表名表还正在被锁，无法创建，可以进行锁表操作！
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)

ysql> use relay;   #使用relay库
Database changed

mysql> create table t1(id int,name char(30));   #创建t1表
Query OK, 0 rows affected (0.02 sec)

mysql> insert into t1 value(001,'zhangsan');    #插入数据
Query OK, 1 row affected (0.03 sec)
 
mysql> drop database relay;      #此时进行误删操作！误删relay数据库
Query OK, 1 row affected (0.01 sec)

2.4定位从库-停止SQL线程、后去延迟日志文件、文件位置，删除数据位置、恢复relay log

bash 复制代码

#定位从库

mysql> show replica status\G;  #查看同步状态
SQL_Delay: 300   #延迟时间300s
SQL_Remaining_Delay: 211    #保留延迟时间剩余211s

mysql> stop replica sql_thread;     #停止SQL线程
Query OK, 0 rows affected (0.01 sec)

mysql> show replica status\G;   #查看同步状态
Relay_Log_File: mysql-slave1-relay-bin.000002   #延迟日志文件
Relay_Log_Pos: 323     #延迟日志起始位置


mysql> show relaylog events in 'mysql-slave1-relay-bin.000002';    #找到误删数据的位置1267
+-------------------------------+------+----------------+-----------+-------------+-----------------------------------------------------------------+
| Log_name                      | Pos  | Event_type     | Server_id | End_log_pos | Info                                                            |
+-------------------------------+------+----------------+-----------+-------------+-----------------------------------------------------------------+
| mysql-slave1-relay-bin.000002 |    4 | Format_desc    |       229 |         126 | Server ver: 8.0.40, Binlog ver: 4                               |
| mysql-slave1-relay-bin.000002 |  126 | Previous_gtids |       229 |         157 |                                                                 |
| mysql-slave1-relay-bin.000002 |  157 | Rotate         |       228 |           0 | binlog.000004;pos=1053                                          |
| mysql-slave1-relay-bin.000002 |  201 | Format_desc    |       228 |           0 | Server ver: 8.0.40, Binlog ver: 4                               |
| mysql-slave1-relay-bin.000002 |  323 | Anonymous_Gtid |       228 |        1130 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'                            |
| mysql-slave1-relay-bin.000002 |  400 | Query          |       228 |        1238 | create database andy /* xid=35 */                               |
| mysql-slave1-relay-bin.000002 |  508 | Anonymous_Gtid |       228 |        1315 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'                            |
| mysql-slave1-relay-bin.000002 |  585 | Query          |       228 |        1426 | create database relay /* xid=36 */                              |
| mysql-slave1-relay-bin.000002 |  696 | Anonymous_Gtid |       228 |        1503 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'                            |
| mysql-slave1-relay-bin.000002 |  773 | Query          |       228 |        1630 | use `relay`; create table t1(id int,name char(30)) /* xid=41 */ |
| mysql-slave1-relay-bin.000002 |  900 | Anonymous_Gtid |       228 |        1709 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'                            |
| mysql-slave1-relay-bin.000002 |  979 | Query          |       228 |        1785 | BEGIN                                                           |
| mysql-slave1-relay-bin.000002 | 1055 | Table_map      |       228 |        1840 | table_id: 109 (relay.t1)                                        |
| mysql-slave1-relay-bin.000002 | 1110 | Write_rows     |       228 |        1889 | table_id: 109 flags: STMT_END_F                                 |
| mysql-slave1-relay-bin.000002 | 1159 | Xid            |       228 |        1920 | COMMIT /* xid=42 */                                             |
| mysql-slave1-relay-bin.000002 | 1190 | Anonymous_Gtid |       228 |        1997 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'                            |
| mysql-slave1-relay-bin.000002 | 1267 | Query          |       228 |        2104 | drop database relay /* xid=43 */                                |
+-------------------------------+------+----------------+-----------+-------------+-----------------------------------------------------------------+
17 rows in set (0.00 sec)

[root@mysql-slave1 ~]# mysqlbinlog --start-position=323 --stop-position=1267 
/data/mysql/mysql-slave1-relay-bin.000002  > /tmp/relay.sql   #将relay log进行备份
[root@mysql-slave1 ~]# mysql -uroot -p -e 'source  /tmp/relay.sql'  # 恢复误删除的数据库 
Enter password:      #输入密码
[root@mysql-slave1 ~]# mysql -uroot -p123     #进入msyql

mysql> select * from relay.t1;    #查看t1表数据
+------+----------+
| id   | name     |
+------+----------+
|   001| zhangsan |     #恢复成功！
+------+----------+
1 row in set (0.00 sec)


#解除从库身份
mysql> stop replica;
Query OK, 0 rows affected (0.01 sec)

mysql> reset replica all;
Query OK, 0 rows affected (0.01 sec)

3.GTID复制

3.1GTID复制原理

GTID是全局事务ID（global transaction identifier），其保证为每一个提交的事务可以生成一个唯一的ID。当事务提交时，MySQL Server在写binlog的时候，会先写一个类型为GTID_Event的特殊Binlog Event，指定下一个事务的GTID，然后再写事务的Binlog。主从同步时GTID_Event和事务的Binlog 都会传递到从库，从库在执行的时候也是用同样的GTID写binlog，这样主从同步以后，就可通过GTID确定从库同步到的位置了。也就是说，无论是级联情况，还是一主多从情况，都可以通过GTID自动找同步位置，而无需像之前那样通过log_file和log_pos找同步位置了。

有两种方式，将二进制日志同步切换为gtid同步和直接进行gtid同步，以下在上述主从同步的基础上进行二进制日志同步切换为gtid同步

3.2主库、从库同时开启强一致性与gtid模式

bash 复制代码

mysql> set global enforce_gtid_consistency=on;   #开启强一致性
Query OK, 0 rows affected (0.00 sec)

mysql> set global gtid_mode=off_permissive; 
Query OK, 0 rows affected (0.00 sec)

mysql> set global gtid_mode=on_permissive;
Query OK, 0 rows affected (0.01 sec)
 
mysql> set global gtid_mode=on;       #开启gtid模式
Query OK, 0 rows affected (0.00 sec)

3.3定位从库

bash 复制代码

#定位从库

mysql> stop replica;  #关闭同步

mysql> CHANGE REPLICATION SOURCE TO SOURCE_AUTO_POSITION = 1;     #切换到gtid模式

mysql> start replica;   #开启模式

mysql> show replica status \G；  #查看同步状态
Replica_IO_Running: Yes
Replica_SQL_Running: Yes

3.4测试

bash 复制代码

#定位主库

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

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

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| andy               |
| cheng              |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
6 rows in set (0.00 sec)

#定位从库

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| andy               |
| cheng              |   #同步成功
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
6 rows in set (0.00 sec)

4.半同步复制

4.1半同步复制原理

主库在应答客户端提交的事务前需要保证至少一个从库接收并将事务写到relay log中，即master将写入binlog的事务传递到slave，主库提交事务，master等待slave回复ACK确认已将数据写入relay log，此时master才会将commit OK结果反馈给客户端，如果出现异常没有收到ACK，那么将自动降级为普通的复制，直到异常修复后又会变为半同步复制。

4.2定位主库

bash 复制代码

#定位主库

mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';  #安装插件

mysql> show plugins;   #判断插件是否安装成功

mysql> set global rpl_semi_sync_master_enabled=1;  #打开半同步开关，可写入配置文件

mysql> set global rpl_semi_sync_master_timeout=3000;#设置主库等待从库回复ack的超时时间为3s默认是10s,可写入配置文件

mysql> show variables like 'rpl_semi_sync_master%'; 
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 3000       |
| rpl_semi_sync_master_trace_level          | 32         |
| rpl_semi_sync_master_wait_for_slave_count | 1          |
| rpl_semi_sync_master_wait_no_slave        | ON         |
| rpl_semi_sync_master_wait_point           | AFTER_SYNC |
+-------------------------------------------+------------+

4.3定位从库

bash 复制代码

#定位从库

mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';

mysql> show plugins;

mysql> set global rpl_semi_sync_slave_enabled=1; #打开半同步开关，可写入配置文件

mysql> show variables like 'rpl_semi%';
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled     | ON    |
| rpl_semi_sync_slave_trace_level | 32    |
+---------------------------------+-------+

mysql> stop replica IO_THREAD;

mysql> start replica IO_THREAD;  #重启IO线程

4.4测试

bash 复制代码

#测试

#定位主库
mysql> use andy;
mysql> create table t1(id int,name varchar(30));

mysql> show status like 'Rpl_semi_sync_master_yes_tx';
+-----------------------------+-------+
| Variable_name               | Value |
+-----------------------------+-------+
| Rpl_semi_sync_master_yes_tx | 1     |
+-----------------------------+-------+   #master成功接收到slave的回复的次数