【MySQL 5.7 Reference Manual】15.4.4 Redo Log Buffer（Redo日志缓冲）

15.4.4 Redo Log Buffer（Redo日志缓冲）

The redo log buffer is the memory area that holds data to be written to the redo log. Redo log buffer size is defined by the innodb_log_buffer_size configuration option. The redo log buffer is periodically flushed to the log file on disk. A large redo log buffer enables large transactions to run without the need to write redo log to disk before the transactions commit. Thus, if you have transactions that update, insert, or delete many rows, making the log buffer larger saves disk I/O.

redo日志缓冲是一块内存空间用于暂存写入redo日志的数据。Redo日志缓冲的大小可通过innodb_log_buffer_size配置项来定义。redo日志缓冲被周期性的刷入磁盘日志文件。一个大型的redo日志缓冲允许大型事务运行时可以不必在事务提交前将redo日志写到磁盘上。因此，如果你有一些事务需要更新、插入、或者删除多行记录，较大的日志缓冲可以节约磁盘I/O。

The innodb_flush_log_at_trx_commit option controls how the contents of the redo log buffer are written to the log file. The innodb_flush_log_at_timeout option controls redo log flushing frequency.

innodb_flush_log_at_trx_commit控制着redo日志的内容写入日志文件的方式。innodb_flush_log_at_timeout选项控制着redo日志刷新的频率。