mysql replication
http://xyz.cinc.biz/2014/10/mysql-replication.html
http://blog.miniasp.com/post/2012/07/04/How-to-setup-MySQL-55-One-way-replication-Master-Slave-mode.aspx
set global slow_query_log = 'ON';
set global log_queries_not_using_indexes = 'ON'set global log_warnings = 1; 修復replacation
解决Mysql复制Relay log read failure 的问题
參考資料：http://xstarcd.github.io/wiki/MySQL/online_mysqlrepl_error.html
常见错误
最常见的3种情况
这3种情况是在HA切换时，由于是异步复制，且sync_binlog=0，会造成一小部分binlog没接收完导致同步报错。
- 第一种：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
- 第二种：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
- 第三种：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 263
异步半同步区别
- 异步复制
简单的说就是master把binlog发送过去，不管slave是否接收完，也不管是否执行完，这一动作就结束了.
- 半同步复制
简单的说就是master把binlog发送过去，slave确认接收完，但不管它是否执行完，给master一个信号我这边收到了，这一动作就结束了。（谷歌写的代码，5.5上正式应用。）
- 异步的劣势
当master上写操作繁忙时，当前POS点例如是10，而slave上IO_THREAD线程接收过来的是3，此时master宕机，会造成相差7个点未传送到slave上而数据丢失。
特殊的情况
- 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
这种情况SLAVE在宕机，或者非法关机，例如电源故障、主板烧了等，造成中继日志损坏，同步停掉。
- 人为失误需谨慎：多台slave存在重复server-id
这种情况同步会一直延时，永远也同步不完，error错误日志里一直出现上面两行信息。解决方法就是把server-id改成不一致即可。
Slave: received end packet from server, apparent master shutdown: Slave I/O thread: Failed reading log event, reconnecting to retry, log 'mysql-bin.000012' at postion 106
问题处理
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：
由于master要删除一条记录，而slave上找不到故报错，这种情况主上都将其删除了，那么从机可以直接跳过。可用命令：
stop slave; set global sql_slave_skip_counter=1; start slave;
如果这种情况很多，可用我写的一个脚本skip_error_replcation.sh，默认跳过10个错误（只针对这种情况才跳，其他情况输出错误结果，等待处理），这个脚本是参考maakit工具包的mk-slave-restart原理用shell写的，功能上定义了一些自己的东西，不是无论什么错误都一律跳过。）
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 ……
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
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: 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: Seconds_Behind_Master: 0 Master_SSL_Verify_Server_Cert: No Last_IO_Errno: 0 Last_IO_Error: Last_SQL_Errno: 0 Last_SQL_Error:
