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， PostgreSQL 在即将发行的 9.4 版本也支持延迟复制，有兴趣的朋友可以查看之前写的 blog: PostgreSQL9.4 : 支持备库延迟复制(delayed standbys) ， 这里简单介绍 MySQL 延迟复制的配置。
MySQL 的主从搭建本文略。 CHANGE MASTER TO 命令指定 MASTER_DELAY 选项即可设置，如下：
一 语法
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CHANGE MASTER TO MASTER_DELAY = 30;
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备注：设置备节点延迟的时间，单位秒。
二 延迟复制配置
从节点设置
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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)
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查看从节点状态
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root@localhost:mysql>select * from slave_relay_log_infoG
* 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: 30
Number_of_workers: 0
Id: 1
1 row in set (0.00 sec)
root@localhost:mysql>show slave statusG
* 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: 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
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: 0
1 row in set (0.00 sec)
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主节点创建表测试
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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)
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备注：在主节点上创建一张测试表并插入一条测试数据。
备节点查询
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root@localhost:mysql>select * from test_delay;
Empty set (0.00 sec)
root@localhost:mysql>select * from test_delay;
Empty set (0.00 sec)
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这时在备节点上还查不到表。
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root@localhost:mysql>show slave statusG
* 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: 15
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
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: 0
1 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)
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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;
三 参考
原创文章，作者：Maggie-Hunter，如若转载，请注明出处：https://blog.ytso.com/239612.html
