线上MYSQL同步报错故障处理⽅法总结前⾔
在发⽣故障切换后，经常遇到的问题就是同步报错，下⾯是最近收集的报错信息。
记录删除失败
在master上删除⼀条记录，⽽slave上不到
Last_SQL_Error: Could not execute Delete_rows event on table hcy.t1;
Can't find record in 't1',
Error_code: 1032; handler error HA_ERR_KEY_NOT_FOUND;
the event's master log mysql-bin.000006, end_log_pos 254
解决⽅法：master要删除⼀条记录，⽽slave上不到报错，这种情况主都已经删除了，那么从机可以直接跳过。stop slave;
set global sql_slave_skip_counter=1;
start slave;
如果这种情况很多，需要针对这种错误专门写相关脚本。
主键重复
在slave已经有该记录，⼜在master上插⼊了同⼀条记录。
Last_SQL_Error: Could not execute Write_rows event on table hcy.t1;
Duplicate entry '2' for key 'PRIMARY',
Error_code: 1062;
handler error HA_ERR_FOUND_DUPP_KEY; the event's master log mysql-bin.000006, end_log_pos 924
解决⽅法：
在slave上⽤desc hcy.t1; 先看下表结构：
mysql> desc hcy.t1;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| id    | int(11) | NO  | PRI | 0      |      |
| name  | char(4) | YES  |    | NULL    |      |
+-------+---------+------+-----+---------+-------+
删除重复的主键
mysql> delete from t1 where id=2;
Query OK, 1 row affected (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;
…
…
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
……
mysql> select * from t1 where id=2;
在master上和slave上再分别确认⼀下。
更新丢失
在master上更新⼀条记录，⽽slave上不到，丢失了数据。
Last_SQL_Error: Could not execute Update_rows event on table hcy.t1;
Can't find record in 't1',
Error_code: 1032;
handler error HA_ERR_KEY_NOT_FOUND;
the event's master log mysql-bin.000010, end_log_pos 794
解决⽅法：
在master上，⽤mysqlbinlog 分析下出错的binlog⽇志在⼲什么。
/usr/local/mysql/bin/mysqlbinlog --no-defaults -v -v --base64-output=DECODE-ROWS mysql-bin.000010 | grep -A '10' 794
#120302 12:08:36 server id 22  end_log_pos 794  Update_rows: table id 33 flags: STMT_END_F
### UPDATE hcy.t1
### WHERE
###  @1=2 /* INT meta=0 nullable=0 is_null=0 */
###  @2='bbc' /* STRING(4) meta=65028 nullable=1 is_null=0 */
### SET
###  @1=2 /* INT meta=0 nullable=0 is_null=0 */
###  @2='BTV' /* STRING(4) meta=65028 nullable=1 is_null=0 */
# at 794
#120302 12:08:36 server id 22  end_log_pos 821  Xid = 60
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
在slave上，查下更新后的那条记录，应该是不存在的。
mysql> select * from t1 where id=2;
Empty set (0.00 sec)
然后再到master查看
mysql> select * from t1 where id=2;
+----+------+
| id | name |
+----+------+
|  2 | BTV  |
+----+------+
1 row in set (0.00 sec)
把丢失的数据在slave上填补，然后跳过报错即可。
mysql> insert into t1 values (2,'BTV');
Query OK, 1 row affected (0.00 sec)
mysql> select * from t1 where id=2;
+----+------+
| id | name |
+----+------+
|  2 | BTV  |
+----+------+
1 row in set (0.00 sec)
mysql> stop slave ;set global sql_slave_skip_counter=1;start slave;
Query OK, 0 rows affected (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;
……
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
……
1236错误, ⼆进制⽂件缺失
误删⼆进制⽂件等各种原因，导致主库mysql-bin.000012⽂件丢失，从库同步失败。
Master_Log_File: mysql-bin.000012
Slave_IO_Running: No
Slave_SQL_Running: Yes
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'⾸先停⽌从库同步
slave stop;
查看主库⽇志⽂件和位置
mysql> show master logs;
+------------------+-----------+
| Log_name        | File_size |
+------------------+-----------+
| mysql-bin.000013 |      154 |
+------------------+-----------+
回从库，使⽇志⽂件和位置对应主库
CHANGE MASTER TO MASTER_LOG_FILE='log-bin.000013',MASTER_LOG_POS=154;
最后，启动从库：
```bash
slave start;
show slave status\G;
Master_Log_File: mysql-bin.000013
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Last_IO_Error:
```
中继⽇志损坏
slave的中继⽇志relay-bin损坏。
Last_SQL_Error: Error initializing relay log position: I/O error reading the header from the binary log
Last_SQL_Error: Error initializing relay log position: Binlog has bad magic number;
It's not a binary log file that can be used by  this version of MySQL
1、⼿⼯修复
解决⽅法：到同步的binlog和POS点，然后重新做同步，这样就可以有新的中继⽇值了。例⼦：
mysql> show slave status\G;
*************************** 1. row ***************************
Master_Log_File: mysql-bin.000010
Read_Master_Log_Pos: 1191
Relay_Log_File: vm02-relay-bin.000005
Relay_Log_Pos: 253
Relay_Master_Log_File: mysql-bin.000010
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: 1593
Last_Error: Error initializing relay log position: I/O error reading the header from the binary log
Skip_Counter: 1
Exec_Master_Log_Pos: 821
Slave_IO_Running ：接收master的binlog信息
Master_Log_File
Read_Master_Log_Pos
Slave_SQL_Running：执⾏写操作
Relay_Master_Log_File
Exec_Master_Log_Pos
以执⾏写的binlog和POS点为准。
Relay_Master_Log_File: mysql-bin.000010
Exec_Master_Log_Pos: 821
mysql> stop slave;
Query OK, 0 rows affected (0.01 sec)
mysql> CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000010',MASTER_LOG_POS=821;
Query OK, 0 rows affected (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.8.22
Master_User: repl
Master_Port: 3306
Connect_Retry: 10
Master_Log_File: mysql-bin.000010
Read_Master_Log_Pos: 1191
Relay_Log_File: vm02-relay-bin.000002
Relay_Log_Pos: 623
Relay_Master_Log_File: mysql-bin.000010            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: 1191
Relay_Log_Space: 778
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:mysql下载失败怎么办
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error: