mysql主从同步失败两种方法

同步之前需要使用dump进行数据复制到从库

Slave_SQL_Running:No的两种解决办法

进入slave服务器，运行：

mysql> show slave status\G

         .......
             Relay_Log_File: localhost-relay-bin.000535
              Relay_Log_Pos: 21795072
      Relay_Master_Log_File: localhost-bin.000094
           Slave_IO_Running: Yes
          Slave_SQL_Running: No
            Replicate_Do_DB: 
        Replicate_Ignore_DB: 
      ......

解决办法一、

Slave_SQL_Running: No
1.程序可能在slave上进行了写操作

2.也可能是slave机器重起后，事务回滚造成的.

一般是事务回滚造成的：
解决办法：

mysql> stop slave ;
mysql> set GLOBAL SQL_SLAVE_SKIP_COUNTER=1;
mysql> start slave ;

解决办法二、（推荐）

首先停掉Slave服务：stop slave
到主服务器上查看主机状态：
记录File和Position对应的值

进入master

mysql> show master status;
+----------------------+----------+--------------+------------------+
| File                 | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+----------------------+----------+--------------+------------------+
| localhost-bin.000094 | 33622483 |              |                  | 
+----------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

然后到slave服务器上执行手动同步：

mysql> change master to 
> master_host='master_ip',
> master_user='user', 
> master_password='pwd', 
> master_port=3306, 
> master_log_file=localhost-bin.000094', 
> master_log_pos=33622483 ;
1 row in set (0.00 sec)
mysql> start slave ;
1 row in set (0.00 sec)

start slave

然后到slave服务器上执行手动同步：

mysql> CHANGE MASTER TO master_host = '101.201.142.142' master_port = 3306 master_user = 'yqjf_slavE' master_password = 'slave2f9r' master_log_file = 'mysql-bin.000574' master_log_pos = 48665419;

启动同步

start slave

查看状态

mysql> show slave status\G
*************************** 1. row ***************************
........
            Master_Log_File: localhost-bin.000094
        Read_Master_Log_Pos: 33768775
             Relay_Log_File: localhost-relay-bin.000537
              Relay_Log_Pos: 1094034
      Relay_Master_Log_File: localhost-bin.000094
           Slave_IO_Running: Yes
          Slave_SQL_Running: Yes
            Replicate_Do_DB:

常见异常ERROR 2061 (HY000): Authentication plugin 'caching_sha2_password' reported error: Authentication requires secure connection

【分析】mysql8默认使用插件caching_sha2_password,有些client连接报这个错误，需要拿到server的public key来加密password。

【解决】加参数可以解决：--get-server-public-key

 mysql -u sha2user -p --get-server-public-key。做主从复制的时候也会碰到这种情况，加餐get_master_public_key=1;

 change master to 

    master_host='192.168.2.135',

    master_port=3306,

    master_user='repl_user',

    master_password='123456',

    master_auto_position=1 ,

    get_master_public_key=1;

查询mysql异常日志

路径： /var/log/mysqld.log