MySQL主从复制之延缓型数据复制
发布时间：2022-03-26 19:41:24 所属栏目：MySql教程 来源：互联网
导读：让MySQL拓扑中的从节点延迟适当的时间，可以帮助避免在主节点上发生的灾难性的错误。 MASTER_DELAY这个属性指定SQL_THREAD会在从节点上暂定多长时间，时间以秒为单位。默认值为0，上限为68年。 mysql stop slave; Query OK, 0 rows affected (0.06 sec) mysq
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让MySQL拓扑中的从节点延迟适当的时间，可以帮助避免在主节点上发生的灾难性的错误。 MASTER_DELAY这个属性指定SQL_THREAD会在从节点上暂定多长时间，时间以秒为单位。默认值为0，上限为68年。 mysql> stop slave; Query OK, 0 rows affected (0.06 sec) mysql> change master to master_delay=20; Query OK, 0 rows affected (0.01 sec) mysql> start slave; 点击(此处)折叠或打开 mysql> stop slave; Query OK, 0 rows affected (0.01 sec) mysql> change master to master_delay=20 ; Query OK, 0 rows affected (0.02 sec) mysql> start slave; Query OK, 0 rows affected (0.02 sec) mysql> show slave status G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.8.57 Master_User: repl Master_Port: 3306 Connect_Retry: 10 Master_Log_File: mysql-bin.000021 Read_Master_Log_Pos: 154 Relay_Log_File: relay-log.000002 Relay_Log_Pos: 320 Relay_Master_Log_File: mysql-bin.000021 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: 154 Relay_Log_Space: 521 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: /usr/local/mysql/certs/ca-cert.pem Master_SSL_CA_Path: Master_SSL_Cert: /usr/local/mysql/certs/client-cert.pem Master_SSL_Cipher: Master_SSL_Key: /usr/local/mysql/certs/client-key.pem 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: 9ad24233-aeef-11e7-aa1b-080027768e58 Master_Info_File: mysql.slave_master_info SQL_Delay: 20 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates 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 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version: 1 row in set (0.00 sec) 可以看到SQL_Delay: 20 下边做一个测试： 在主节点对测试表做truncate 点击(此处)折叠或打开 mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> truncate table tb_admin_bak; Query OK, 0 rows affected (0.02 sec) 在从节点查看表信息 点击(此处)折叠或打开 mysql> select count(*) from tb_admin_bak; +----------+ | count(*) | +----------+ | 1 | +----------+ 1 row in set (0.02 sec) mysql> select count(*) from tb_admin_bak; +----------+ | count(*) | +----------+ | 1 | +----------+ 1 row in set (0.00 sec) mysql> show full processlist G *************************** 1. row *************************** Id: 3 User: root Host: localhost db: test Command: Query Time: 0 State: starting Info: show full processlist *************************** 2. row *************************** Id: 8 User: system user Host: db: NULL Command: Connect Time: 334 State: Waiting for master to send event Info: NULL *************************** 3. row *************************** Id: 9 User: system user Host: db: NULL Command: Connect Time: 100 State: Waiting until MASTER_DELAY seconds after master executed event Info: NULL 3 rows in set (0.00 sec) mysql> select count(*) from tb_admin_bak; +----------+ | count(*) | +----------+ | 0 | +----------+ 1 row in set (0.00 sec) 发现从节点此表数据刚开始并没有被清理，20S之后数据才被清理掉。 在主库删除测试表 点击(此处)折叠或打开 mysql> drop table tb_admin_bak; Query OK, 0 rows affected (0.06 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | +----------------+ 1 row in set (0.00 sec) 在从库查看表是否存在 点击(此处)折叠或打开 mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | | tb_admin_bak | +----------------+ 2 rows in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | +----------------+ 1 row in set (0.00 sec) mysql> show tables; +----------------+ | Tables_in_test | +----------------+ | tb_admin | +----------------+ 1 row in set (0.00 sec) 一段时间之后，测试表才被删除。 （编辑：晋中站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
