Re: NOARCHIVELOG and rollback segments

"Howard J. Rogers" <hjr_at_dizwell.com> wrote in message news:<3fa9829d$0$9607> >
>

 Each undo segment has a segment header block. Therefore,
> huge tablespace means lots of undo segment header blocks clogging up my
> buffer cache.
>

Can you clarify a bit? Does ORACLE only cache the rbs header block?

>
> >It's been around for more than a couple of years,
>
> Not really. I seem to recall teaching one of the first 9i courses in Oz
> around about August last year. So just over a year and a bit. It's still not
> totally mature, I think.
>

Really? I thought it has been around since the inception of 9i? Hasn't 9i been around for more than a couple of years now?

> > I would assume most of the kinks would have been fixed by now.
>
> Assuming anything is always risky! Particularly with AUM. It's pretty close,
> and I've never encountered any disasters with it, but check Metalink very,
> very carefully.
>

I actually did search Metalink and did not see any complaints about AUM. One guy claimed he loaded 37 millions rows of data without problems. I actually had this idea of setting UNDO_RETENTION to very, very high and create a huge undo tbs. The idea is to force ORACLE to use up the entire undo tbs, which will take a long time, before it starts recycling the the segments. I figured this would basically cure the ORA-01555. I was just not quite sure what would happen if ORACLE indeed uses up a huge undo tbs. Is the flooded buffer cache your personal experience or your intelligent guess? From your description, fewer long transactions is better suited for AUM than lots of shorter transactions, right?

John Received on Thu Nov 06 2003 - 00:53:00 CST