oracle lgwr如何写redolog

oracle lgwr如何写redolog

 

例如一个实例只有一个redo thread,即一个LGWR，对吧？

 

但是一个日志组，假设里面有3个日志成员，那么一个LGWR如何同时向3个日志成员写呢？
 

明显做不到啊？在一个时间段内，一个thread只能写一个日志成员吧？

 

from：Yong Huang
 

log file headers are written sequentially (wait event: log file single write). Log file bodies are written in parallel (event: log file parallel write). As guoyJoe said, OS level async write can handle it.

 

日志文件头连续写的，日志文件的内容是并行写的，主要是通过 os 的异步i/o来实现的。