> redo buffer的写入 也是 lgwr吗？
No. Server (shadow) processes write to log buffer. LGWR writes redo records from the log buffer to the log file.
> 而undo buffer因为就是在db cache buffer,所以也是DBWR读入的吗？
Not quite sure what you mean. "Undo buffer" is just a buffer in buffer cache that corresponds to a block in an undo tablespace. Treat it like any other data block. It's written into buffer cache by a server process and written out to datafiles by DBWn.
Yong Huang
Yong Huang 发表于 2012-2-28 00:34
> redo buffer的写入 也是 lgwr吗？
No. Server (shadow) processes write to log buffer. LGWR writes...
我有个疑问
既然 “Server (shadow) processes write to log buffer”
那为何不专门也命名一个 logreader的进程呢？
同理
“It's written into buffer cache by a server process ”
那么这个进程为何不命名为dbreader呢？
这样不是要明确很多吗？
> 涉及IO（特别是异步），就需要一个专门的进程来完成
A server process can always read datafiles. But normally only DBWn can write to them. Also remember a server process can read and write a tempfile.
Yong Huang
