MySQL复制的管理和维护

1.查看主库

mysql> show master status;

mysql> show master status;
+------------------+-----------+--------------+------------------+
| File             | Position  | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+-----------+--------------+------------------+
| mysql-bin.000013 | 971159980 |              |                  |
+------------------+-----------+--------------+------------------+
1 row in set (0.00 sec)

mysql> show master logs;

mysql> show master logs;
+------------------+------------+
| Log_name         | File_size  |
+------------------+------------+
| mysql-bin.000011 | 1073949250 |
| mysql-bin.000012 | 1073751139 |
| mysql-bin.000013 |  971159980 |
+------------------+------------+
3 rows in set (0.00 sec)

mysql> show binlog events in ‘mysql-bin.000013‘ from 971245404;

mysql> show binlog events in ‘mysql-bin.000013‘ from 971245404;
+------------------+-----------+-------------+-----------+-------------+-----------------------------------------+
| Log_name         | Pos       | Event_type  | Server_id | End_log_pos | Info                                    |
+------------------+-----------+-------------+-----------+-------------+-----------------------------------------+
| mysql-bin.000013 | 971245404 | Query       |         1 |   971245474 | BEGIN                                   |
| mysql-bin.000013 | 971245474 | Table_map   |         1 |   971245651 | table_id: 175 (attend.sys_user)         |
| mysql-bin.000013 | 971245651 | Update_rows |         1 |   971246116 | table_id: 175 flags: STMT_END_F         |
| mysql-bin.000013 | 971246116 | Table_map   |         1 |   971246185 | table_id: 176 (attend.sys_user_branch)  |
| mysql-bin.000013 | 971246185 | Write_rows  |         1 |   971246266 | table_id: 176 flags: STMT_END_F         |
| mysql-bin.000013 | 971246266 | Table_map   |         1 |   971246335 | table_id: 176 (attend.sys_user_branch)  |
| mysql-bin.000013 | 971246335 | Delete_rows |         1 |   971246416 | table_id: 176 flags: STMT_END_F         |
| mysql-bin.000013 | 971246416 | Xid         |         1 |   971246443 | COMMIT /* xid=3065249192 */             |           |
+------------------+-----------+-------------+-----------+-------------+-----------------------------------------+
8 rows in set (0.00 sec)

2.查看复制库延迟

mysql> show slave status\G

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.10.106
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000013
          Read_Master_Log_Pos: 971434196
               Relay_Log_File: mysql-relay-bin.000002
                Relay_Log_Pos: 126333146
        Relay_Master_Log_File: mysql-bin.000013
             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: 971434196
              Relay_Log_Space: 126333302
              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: 1
1 row in set (0.00 sec)

Seconds_Behind_Master：

·显示备库延迟，但不准确

·将服务器当前的时间戳与二进制日志中的事件时间戳相对比，所以只有在执行复制事件时才能报告延迟

·如果复制线程没有运行，延迟报告为null

·有时复制发生错误时，该参数为显示为0，而不是显示错误

·有时，即使复制线程正常运行，也不能估算延迟，而是显示0或null

·大事务会导致延迟波动

检测延迟比较好的方法是：使用heartbeat record。

3. 确认主备是否一致

mysql没有内建方法来确认主备是否一致。checksum table可以校验数据，但是复制正在进行时，这种方法不可行。

可以使用percona提供的pt-table-checksum来校验主备数据是否一致。（结合pt-table-sync使用，重新同步数据）