今天看见主库binlog日志非常大，于是使用reset master命令清空日志

mysql> reset master;

Query OK, 0 rows affected (1 min 59.87 sec)

结果从库就报错了

mysql> show slave status\G;

*************************** 1. row ***************************

Slave_IO_State:

Master_Host: 192.168.129.150

Master_User: replicat

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: mysql-bin.000312

Read_Master_Log_Pos: 2029035

Relay_Log_File: mysql-relay-bin.000945

Relay_Log_Pos: 2020198

Relay_Master_Log_File: mysql-bin.000312

Slave_IO_Running: No

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: 1

Exec_Master_Log_Pos: 2029035

Relay_Log_Space: 2029418

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: 1236

Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'Could not find first log file name in binary log index file'

Last_SQL_Errno: 0

Last_SQL_Error:

Replicate_Ignore_Server_Ids:

Master_Server_Id: 2

Master_UUID: 124deecd-401b-11e6-b4e1-40f2e9de1e12

Master_Info_File: /data/DB/mysql/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: 160808 11:08:49

Last_SQL_Error_Timestamp:

Master_SSL_Crl:

Master_SSL_Crlpath:

Retrieved_Gtid_Set:

Executed_Gtid_Set:

Auto_Position: 0

1 row in set (0.00 sec)

再看下主库日志，已经重新开始了，不再是mysql-bin.000312

mysql> show master status;

+------------------+----------+--------------+------------------+-------------------+

| File| Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |

+------------------+----------+--------------+------------------+-------------------+

| mysql-bin.000001 | 216484 | | | |

+------------------+----------+--------------+------------------+-------------------+

1 row in set (0.00 sec)

解决方法，重新设置slave进程

mysql> stop slave;

Query OK, 0 rows affected (0.01 sec)

mysql> change master to master_host='192.168.129.150',

-> master_user='replicat',

-> master_password='passw',

-> master_log_file='mysql-bin.000001',

-> master_log_pos=120;

Query OK, 0 rows affected, 2 warnings (0.05 sec)

mysql> start slave;

Query OK, 0 rows affected (0.02 sec)

mysql> show slave status\G;

*************************** 1. row ***************************

Slave_IO_State: Waiting for master to send event

Master_Host: 192.168.129.150

Master_User: replicat

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: mysql-bin.000001

Read_Master_Log_Pos: 310425

Relay_Log_File: mysql-relay-bin.000002

Relay_Log_Pos: 310588

Relay_Master_Log_File: mysql-bin.000001

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: 310425

Relay_Log_Space: 310761

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: 2

Master_UUID: 124deecd-401b-11e6-b4e1-40f2e9de1e12

Master_Info_File: /data/DB/mysql/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:

Executed_Gtid_Set:

Auto_Position: 0

1 row in set (0.00 sec)

问题虽然解决了，但是从报错记录来看

Read_Master_Log_Pos: 2029035

Relay_Log_Pos: 2020198

中间已经有一部分数据没有同步到从库，但因为这个数据库的OLAP系统，从业务了解没有大碍，所以不用担心数据不一致的情况，所以主库执行reset matser是一个非常危险的动作