mysql主备异常后的数据同步

1、锁定正常库

flush table with read lock;

锁定后查询正常，数据不能修改插入操作。

2、导出库中的数据

mysqldump -uroot -p123456 --opt -R test > /home/bakdb.sql

注：如果出现异常信息（mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect）使用下面命令，socket在my.cnf文件中

mysqldump --socket=/var/lib/mysql/mysql.sock -uroot -p123456 --opt -R test > /home/bakdb.sql

3、查看主备数据库的信息

show master status;

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000006 |      726 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.01 sec)

mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000003 |     2060 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

4、在从库上停止slave

stop slave;

5、导入备份的数据文件

mysql> source /home/bak.sql

6、重新设置同步节点

   下面操作解锁库，并关闭slave后进行操作

stop slave;

 unlock tables;

CHANGE MASTER TO master_host = '192.168.123.82',
 master_port = 3306,
 master_user = 'root',
 master_password = '123456',
 master_log_file = 'mysql-bin.000003',
 master_log_pos = 2060;

CHANGE MASTER TO master_host = '192.168.123.78',
 master_port = 3306,
 master_user = 'root',
 master_password = '123456',
 master_log_file = 'mysql-bin.000006',
 master_log_pos = 726;

7、正常从库异常不需要上面设置，重新启动后会同步数据。