MySQL 5.6 已经支持延迟的流复制， 可设置备节点的延迟时间， 延迟复制是有意义的，例如防止主节点数据误删，查看数据库历史状态等。

重点：延迟复制实在原有的主从复制基础上、所以先要有主从复制的环境，然后配置延迟复制.  

一、 语法： 

CHANGE MASTER TO MASTER_DELAY = 30;---表示延迟30s

 备注：设置备节点延迟的时间，单位秒。

二、 配置延迟复制

登录从节点服务器进行设置：

root@localhost:mysql>stop slave;Query OK, 0 rows affected (0.21 sec)root@localhost:mysql>CHANGE MASTER TO MASTER_DELAY = 30;Query OK, 0 rows affected (0.17 sec)root@localhost:mysql>start slave;Query OK, 0 rows affected (0.27 sec)

三、查看从节点状态

root@localhost:mysql>select * from slave_relay_log_info\G*************************** 1. row ***************************  Number_of_lines: 7   Relay_log_name: ./db2-relay-bin.000007    Relay_log_pos: 281  Master_log_name: bin-log.000041   Master_log_pos: 361        Sql_delay: 30Number_of_workers: 0               Id: 11 row in set (0.00 sec)root@localhost:mysql>show slave status\G*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.37                  Master_User: rep1                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: bin-log.000040          Read_Master_Log_Pos: 604               Relay_Log_File: db2-relay-bin.000002                Relay_Log_Pos: 281        Relay_Master_Log_File: bin-log.000040             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: 604              Relay_Log_Space: 452              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: 0Master_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                  Master_UUID: 0c130d47-22bb-11e4-aaaa-000c2986ac80             Master_Info_File: mysql.slave_master_info                    SQL_Delay: 30          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: 01 row in set (0.00 sec)

root@localhost:mysql>create table test_delay(id int4 primary key,                     create_time datetime default current_timestamp);  Query OK, 0 rows affected (0.59 sec)root@localhost:mysql>insert into test_delay (id) values(1); Query OK, 1 row affected (0.07 sec)

五、备节点查询

root@localhost:mysql>select * from test_delay;Empty set (0.00 sec)root@localhost:mysql>select * from test_delay;Empty set (0.00 sec)这时在备节点上还查不到表。root@localhost:mysql>show slave status\G*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.37                  Master_User: rep1                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: bin-log.000040          Read_Master_Log_Pos: 1013               Relay_Log_File: db2-relay-bin.000002                Relay_Log_Pos: 281        Relay_Master_Log_File: bin-log.000040             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: 604              Relay_Log_Space: 861              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: 15Master_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                  Master_UUID: 0c130d47-22bb-11e4-aaaa-000c2986ac80             Master_Info_File: mysql.slave_master_info                    SQL_Delay: 30          SQL_Remaining_Delay: 14      Slave_SQL_Running_State: Waiting until MASTER_DELAY seconds after master executed event           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: 01 row in set (0.00 sec)root@localhost:mysql>select * from test_delay;+----+---------------------+| id | create_time         |+----+---------------------+|  1 | 2014-12-12 14:38:47 |+----+---------------------+1 row in set (0.00 sec)

六、备注: 发现备节点在 30 秒后才能查到新建的表，这里有三个字段显示延迟的信息：

       SQL_Delay: 显示已设置的主备延迟的时间，单位秒;

       SQL_Remaining_Delay: 显示剩余的主备延迟时间，单位秒;

       Slave_SQL_Running_State: 表示 SQL thread 状态;