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 <gogala@xxxxxxxxxxxxx> To: cemail_219@xxxxxxxxxxx CC: oracle-l <oracle-l@xxxxxxxxxxxxx> 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 are
> 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 free)?
-- Mladen Gogala http://www.mgogala.com
-- //www.freelists.org/webpage/oracle-l
