中繼日誌

中繼日誌來自Master的二進位制日誌，I / O執行緒從Master讀取，然後寫入本地的一類日誌，類似於binary log。作為SQL執行緒的輸入，中繼日誌中的事件將透過SQL執行緒來重演，從而實現複製。

The relay log consists of the events read from the binary log of the master and written by the slave I/O thread. Events in the relay log are executed on the slave as part of the SQL thread.

相關的引數：
mysql> show variables like '%relay%'; 
+-----------------------+----------------+ 
| Variable_name | Value | 
+-----------------------+----------------+ 
| max_relay_log_size | 0 | 
| relay_log | | 
| relay_log_index | | 
| relay_log_info_file | relay-log.info | 
| relay_log_purge | ON | 
| relay_log_recovery | OFF | 
| relay_log_space_limit | 0 | 
| sync_relay_log | 0 | 
| sync_relay_log_info | 0 | 
+-----------------------+----------------+

sync_relay_log

• Description: The MariaDB server will synchronize its  to disk after this many writes to the log. The default until  was 0, in which case the operating system handles flushing the file to disk. 1 is the safest, but slowest, choice, since the file is flushed after each write. If autocommit is enabled, there is one write per statement, otherwise there's one write per transaction. If the disk has cache backed by battery, synchronization will be fast and a more conservative number can be chosen.
• Commandline: --sync-relay-log=#
• Scope: Global
• Dynamic: Yes
• Data Type: numeric
• Default Value: 10000 (>= ), 0 (<= )

relay_log_purge

• Description: If set to 1 (the default),  will be purged as soon as they are no longer necessary.
• Commandline: --relay-log-purge={0|1}
• Scope: Global
• Dynamic: Yes
• Data Type: boolean
• Default Value: ON
  
  完整的引數可以參考。