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上找不到
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上找不到报错，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上找不到，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，查找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 MySQL1、手工修复
解决方法：找到同步的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: 821mysql> 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: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error: