今天搭建测试环境MySQL主从服务器，原本一切正常。
后修改了主机名称于是将服务重启了下，结果出现从库同步出现异常，1872的报错：
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: my-master
Master_User: rep
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 154
Relay_Log_File: my-slave-relay-bin.000008
Relay_Log_Pos: 273
Relay_Master_Log_File: mysql-bin.000003
Slave_IO_Running: No
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: 1872
Last_Error: Slave failed to initialize relay log info structure from the repository
Skip_Counter: 0
Exec_Master_Log_Pos: 154
Relay_Log_Space: 0
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: 1872
Last_SQL_Error: Slave failed to initialize relay log info structure from the repository
Replicate_Ignore_Server_Ids:
Master_Server_Id: 0
Master_UUID: aa3f28b6-cf2c-11e8-8169-faae12137300
Master_Info_File: /data/mysql/data/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: 181015 16:43:36
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)
经过查找，这种情况一般是由于从库Crash，然后重新启动后会出现的状况。
据其说明，经过操作问题已经得到解决，特此记录。
方法如下：
mysql> reset slave;
Query OK, 0 rows affected (0.01 sec)
mysql> start slave IO_THREAD;
Query OK, 0 rows affected (0.12 sec)
mysql> stop slave IO_THREAD;
Query OK, 0 rows affected (0.06 sec)
mysql> reset slave;
Query OK, 0 rows affected (0.10 sec)
mysql> start slave;
Query OK, 0 rows affected (0.29 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: my-master
Master_User: rep
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 154
Relay_Log_File: my-slave1-relay-bin.000008
Relay_Log_Pos: 367
Relay_Master_Log_File: mysql-bin.000004
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: 154
Relay_Log_Space: 791
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: 220108
Master_UUID: aa3f28b6-cf2c-11e8-8169-faae12137300
Master_Info_File: /data/mysql/data/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)