Re: Data Buffer Cache

Good question. They don't exactly go into details in the Concepts manual; I would assume that PMON must signal DBWn to write undo out to the disk. There must also be a rule that DBWn must write redo buffers before it can
write buffers to the database files.
These are just my guesses. I hope somebody who KNOWS will respond. Mike

"Pinaki" <bpinaki123_at_indiatimes.com> wrote in message news:96eccafc.0209100807.5c488661_at_posting.google.com...
> Hello ,
>
> I am working in Oracle 8.1.7
> I am issuing a update statement..."Update tab set x=y where z='abc'
> from a session.I do not commit or rollback and no further statements are
 fired
> from session for 10-15 mins...
> From what I understand the previous image is stored in the Rollback
 segment and
> redo information is stored in the Redo log buffer.
> The DBWn meanwhile starts writing the dirty buffers to the
 disk(in
> case of any event such as a log switch etc.).At this point of time some of
 my
> data is in the buffer cache and some in the disk.Now I issue a rollback
 from my
> session.How does oracle handle this situation and take me back to a
 position as
> if nothing has happened at all...
>
> Thanks,
> Pinaki
Received on Tue Sep 10 2002 - 14:54:25 CDT