主从GTID复制修复

清疚 2022-06-17 02:20 159阅读 0赞

### 介绍 ###

GTID是5.6新增特性，减少DBA运维的工作。在以前一主两从架构下当主库M1发生故障我们需要选择一个从库S1作为新的主库，但是S2要重新change master 到新主库上 这时master\_log\_file和master\_log\_pos我们怎么获取到呢？在没有GTID时 MHA架构帮我们解决了这个问题，在有了GTID情况下 我们只需要在S2上面重新change master 下 设置MASTER\_AUTO\_POSITION = 1即可。 本文介绍下在GTID复制下遇到了错误如何解决。

### 场景描述 ###

使用show slave status\\G 查看主备复制状态时 错误如下:

[root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 12:56:57]>SHOW SLAVE STATUS\G
       *************************** 1. row ***************************
       Slave_IO_State: Waiting for master to send event
       Master_Host: 10.10.30.101
       Master_User: repl
       Master_Port: 3306
       Connect_Retry: 10
       Master_Log_File: mysql-bin.000003
       Read_Master_Log_Pos: 28074558
       Relay_Log_File: mysql-relay-bin.000011
       Relay_Log_Pos: 100311
       Relay_Master_Log_File: mysql-bin.000003
       Slave_IO_Running: Yes
       Slave_SQL_Running: No
       Replicate_Do_DB:
       Replicate_Ignore_DB:
       Replicate_Do_Table:
       Replicate_Ignore_Table:
       Replicate_Wild_Do_Table:
       Replicate_Wild_Ignore_Table:
       Last_Errno: 1007
       Last_Error: Error 'Can't create database 'dhy2'; database exists' on query. Default database: 'dhy2'. Query: 'create database dhy2'
       Skip_Counter: 0
       Exec_Master_Log_Pos: 28073671
       Relay_Log_Space: 287925
       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: NULL
       Master_SSL_Verify_Server_Cert: No
       Last_IO_Errno: 0
       Last_IO_Error:
       Last_SQL_Errno: 1007
       Last_SQL_Error: Error 'Can't create database 'dhy2'; database exists' on query. Default database: 'dhy2'. Query: 'create database dhy2'
       Replicate_Ignore_Server_Ids:
       Master_Server_Id: 101
       Master_UUID: dd2a02a3-f0be-11e5-af62-0050563a97cc
       Master_Info_File: mysql.slave_master_info
       SQL_Delay: 0
       SQL_Remaining_Delay: NULL
       Slave_SQL_Running_State:
       Master_Retry_Count: 86400
       Master_Bind:
       Last_IO_Error_Timestamp:
       Last_SQL_Error_Timestamp: 160408 12:57:02
       Master_SSL_Crl:
       Master_SSL_Crlpath:
       Retrieved_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:70261-71462
       Executed_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:1-71459,
       e28420fb-f0be-11e5-af62-0050562edd64:1-81209
       Auto_Position: 0
       1 row in set (0.00 sec)

根据报错描述:

Last_SQL_Error: Error 'Can't create database 'dhy2'; database exists' on query. Default database: 'dhy2'. Query: 'create database dhy2' 
       dhy2 这个数据库已经在备库存在

我们在备库上面show database 查看dhy2这个数据库确实是存在的:

### 修改过程 ###

当我们使用GTID复制时，不能像传统复制一样跳过事务，只能注册一个空的事务骗过MySQL。具体操作步骤如下:

*  查看当前备份的GTID执行情况

Retrieved_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:70261-71462
       Executed_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:1-71459,
       e28420fb-f0be-11e5-af62-0050562edd64:1-81209
       Auto_Position: 0

Retrieved\_Gtid\_Set 代表已经接受到的GTID集合   
Executed\_Gtid\_Set 代码已经执行的GTID集合

针对上面GTID执行情况 我们可以看到:

Retrieved_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:70261-71462
       Executed_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:1-71459

接收到了71462 执行到了71459就报错了。

*  手工注册事务

[root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 12:59:41]>stop slave;
       Query OK, 0 rows affected (0.00 sec)
       
       [root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:04:57]>set gtid_next='dd2a02a3-f0be-11e5-af62-0050563a97cc:71460';
       Query OK, 0 rows affected (0.00 sec)
       
       [root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:05:23]>begin;
       Query OK, 0 rows affected (0.00 sec)
       
       [root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:05:29]>commit;
       Query OK, 0 rows affected (0.02 sec)
       
       [root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:05:31]>SET GTID_NEXT='AUTOMATIC';
       Query OK, 0 rows affected (0.00 sec)
       
       [root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:05:36]>start slave;
       Query OK, 0 rows affected (0.00 sec)

这里需要注意的是

set gtid_next='dd2a02a3-f0be-11e5-af62-0050563a97cc:71460'; 这个值是
       Executed_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:1-71459 71459这个GTID+1
       并且 uuid一定是Retrieved_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:70261-71462 接收到这里显示的uuid

*  再次查看show slave status\\G 已经恢复正常

[root@shadow1:/root 5.6.28-log_Instance1 root@localhost:test 13:05:39]>show slave status\G
       *************************** 1. row ***************************
       Slave_IO_State: Waiting for master to send event
       Master_Host: 10.10.30.101
       Master_User: repl
       Master_Port: 3306
       Connect_Retry: 10
       Master_Log_File: mysql-bin.000003
       Read_Master_Log_Pos: 28275288
       Relay_Log_File: mysql-relay-bin.000012
       Relay_Log_Pos: 21794
       Relay_Master_Log_File: mysql-bin.000003
       Slave_IO_Running: Yes
       Slave_SQL_Running: Yes
       Replicate_Do_DB:
       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: 28275288
       Relay_Log_Space: 302335
       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: 101
       Master_UUID: dd2a02a3-f0be-11e5-af62-0050563a97cc
       Master_Info_File: mysql.slave_master_info
       SQL_Delay: 0
       SQL_Remaining_Delay: NULL
       Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
       Master_Retry_Count: 86400
       Master_Bind:
       Last_IO_Error_Timestamp:
       Last_SQL_Error_Timestamp:
       Master_SSL_Crl:
       Master_SSL_Crlpath:
       Retrieved_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:70261-72005
       Executed_Gtid_Set: dd2a02a3-f0be-11e5-af62-0050563a97cc:1-72005,
       e28420fb-f0be-11e5-af62-0050562edd64:1-81209
       Auto_Position: 0