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Re: Flush UNDOTBS?

From: J. Dex <>
Date: Tue, 07 Feb 2006 07:53:21 -0500
Message-ID: <BAY115-F260CE1524D104A96E49FB6A5010@phx.gbl>

I was trying to run an import. The import failed as it runs out of UNDO. After realizing that the process had died, I wanted to start another import and noticed that UNDO was still 50% used. I have already added an enormous amount of space. My import is running with commit=y and a reasonable size buffer.

>From: Mladen Gogala <>
>CC: oracle-l <>
>Subject: Re: Flush UNDOTBS?
>Date: Tue, 07 Feb 2006 00:14:32 -0500
>On 02/06/2006 10:10:01 PM, J. Dex wrote:
> > How can the UNDOTBS be flushed so that it isn't used?
> > I've got a database where there aren't any processes running, no users
> > using it but UNDOTBS appears to be 50% used. I thought it was maybe
>just a
> > high water mark except that as soon as I kick off an import it looks
>like it
> > starts filling from the 50% used and going up from there.
> > I have also bounced the database and it still appears to be 50% used.
>Dex, what is your problem? What problem are you trying to solve? I could
>recommend some things, like using fdisk or dd-ing /dev/zero into the files
>comprising the undo tablespace, but that would make some people jealous
>and would probably start hating me. Before I dispense advice like that,
>let's try with few basic questions:
>1) Er, what's up doc? What are you trying to do and why do you think
> that "flushing UNDOTBS" would solve your problem?
>2) Are you aware that something has allocated that space and, even if you
> do, by some miracle, manage to "flush the UNDOTBS", without destroying
> your database, that something is likely to do allocate it again?
>3) Are you aware that UNDO tablespace usually contains information vital
> for performing recovery and that, if you don't do it right, stand a
> good chance to destroy your database?
>4) Have you read "Expert Oracle Database Architecture" or "Effective Oracle
>by Design"?
> Both books are very good. There seems to be some confusion about what
>is used
> space and how does the space get liberated (converted from used to
>Mladen Gogala

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Received on Tue Feb 07 2006 - 06:53:21 CST

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