Re: Delayed block cleanout and changing automatic undo tablespace

From: Daniel Fink <Daniel.Fink_at_Sun.COM>
Date: Tue, 20 Jul 2004 07:11:24 -0600
Message-id: <40FD19FC.1010906@sun.com>

I'm going to take the easy question first...

If you are using AUM, you cannot offline undo segments without switch= ing undo tablespaces. You also can't create new ones or drop=20 old ones. If something happens that creates a bunch of undo segments = (another issue), you are stuck with them until you are able to=20 drop the tablespace.

If you bounce the database, you will see that a limited number of seg= ments are online. As transactions are processed, segments are=20 onlined or created as the system sees fit. You no longer have any con= trol over your undo.

I have a rather detailed paper and presentation about undo at www.opt= imaldba.com/library.html.

Regards,
Daniel Fink

Tim Onions wrote:
> Many thanks for the fast response. Sorry to ask a dumb question but=
with
> AUTO UNDO in 9i how can one "...offline the undo segments..". There=
are no
> active transactions on the segments in the old large undo tablespac=
e show
> via V$transaction.

>=20

> Thanks

>=20

> T=AC
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Received on Tue Jul 20 2004 - 08:08:12 CDT