我设置了从主服务器到从服务器的MySQL复制。 “ SHOW SLAVE STATUS \ G”显示不断增加的Seconds_Behind_Master。这是从最旧（顶部）到最新（底部）的三个连续结果。有人知道怎么了吗？.................................... ................................................... ................................................... ................................................... ................................................... .......
1
mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
Slave_IO_State: Queueing master event to the relay log
Master_Host: <excluding>
Master_User: <excluding>
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.002723
Read_Master_Log_Pos: 893947806
Relay_Log_File: design-hotels-database-relay-bin.000002
Relay_Log_Pos: 7692403
Relay_Master_Log_File: mysql-bin.002723
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: starwood_sop,starwood_blp
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: 192464416
Relay_Log_Space: 709176017
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: 76613
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: 3
Master_UUID:
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Reading event from the relay log
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 (0.04 sec)
2
mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
Slave_IO_State: Queueing master event to the relay log
Master_Host: <excluding>
Master_User: <excluding>
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.002723
Read_Master_Log_Pos: 908310158
Relay_Log_File: design-hotels-database-relay-bin.000002
Relay_Log_Pos: 7906291
Relay_Master_Log_File: mysql-bin.002723
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: starwood_sop,starwood_blp
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: 192678304
Relay_Log_Space: 723538369
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: 76698
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: 3
Master_UUID:
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Reading event from the relay log
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 (0.06 sec)
3
mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
Slave_IO_State: Queueing master event to the relay log
Master_Host: <excluding>
Master_User: <excluding>
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.002723
Read_Master_Log_Pos: 945765663
Relay_Log_File: design-hotels-database-relay-bin.000002
Relay_Log_Pos: 8389913
Relay_Master_Log_File: mysql-bin.002723
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: starwood_sop,starwood_blp
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: 193161926
Relay_Log_Space: 760993874
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: 76870
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: 3
Master_UUID:
Master_Info_File: /var/lib/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Reading event from the relay log
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 (0.04 sec)
答案 0 :(得分：1)
好吧，Exec_Master_Log_Pos也在增加，这表明SQL线程实际上正在工作并且正在应用更改。只是速度不够快，无法跟上传入日志，而Read_Master_Log_Pos
Exec-pos Read-pos
1: 192464416 893947806
2: 192678304 (+213,888) 908310158 (+14,362,352
3: 193161926 (+483,622) 945765663 (+37,455,505)
因此，传入日志（Read-pos）到达的速度比复制能够在从属实例上执行更改的速度高很多倍。
复制延迟是一个复杂的问题，并且有很多原因。 您可以使用许多配置设置来帮助提高从服务器上的吞吐量。您没有描述任何有关当前配置，数据库更改或正在更改的表的性质的信息，因此我无法提出真正有根据的建议。但以下是我通常会进行的一些典型更改：
innodb_buffer_pool_size = <high> # depends on server RAM and other factors
innodb_log_file_size = 1G # or more
innodb_flush_log_at_trx_commit = 2
master_info_repository = TABLE
relay_log_info_repository = TABLE
relay_log_recovery = ON
sync_master_info = 0
binlog_format = ROW # make sure all tables have PRIMARY KEY constraints
有关这些选项的详细信息，请参阅MySQL文档。
即使有所有这些调优技巧，最终您可能也会遇到一个极限，那就是从属服务器能够在单个线程中重放主服务器上多个线程中创建的更改。
您也许可以使用多线程从站，但这并不像听起来那样简单，因此在尝试之前，您需要阅读有关它的更多信息。
即使具有调整和多线程从属，也有可能达到硬件极限。它根本无法足够快地处理更改。您可以将硬件升级到更快的CPU和更快的存储。
另一个选择是降低对主数据库的更改率。在主节点上进行油门更改，或者在多个主节点及其各自的从节点上部署多个主节点，并在多个主节点之间平衡更改。