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resizing rollback segments

Posted on 2011-03-21
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Last Modified: 2013-12-19
I have SUN Solaris 10 - Oracle 10.2.4
I tried using auto undo but performance was horrible - my Friday night archive never finished.
It ran for over 24 hours instead of 3 or 4 hours.

So I have put undo back to manual.
I want to resize the rollback segments to make them bigger.

1. Can I do this on the fly with production up and running.
2. How do I ensure that there is nothing being lost if I take a segment offline, drop it and recreate it?
3. initial and next are currently set 20 8k with optimal at 16k  - would 10 or 15k initial/next be better?
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Question by:bkreynolds48
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4 Comments
 
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by:sdstuber
ID: 35182709
force several log switches, wait until "archived" becomes yes, then drop and recreate before the looping cycles back around to the one you're working with
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johnsone earned 2000 total points
ID: 35182874
We are talking about rollback/undo segments, not redo.  Rollback/undo never gets to an archived status.

Yes, you can do this on the fly with production up and running.

Do not worry about losing information in offline segments.  Oracle will not let you drop the segment if there is a transaction that is using it.

I would still suggest that you do this when no large jobs are running.  There is a possibility you could create an artificial ORA-01555 because of dropping a segment.

Be sure when you are done dropping and creating the segments that you update the rollback_segs parameter.
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by:sdstuber
ID: 35183147
oops, right,

  read undo but put redo in my head

nevermind my post.

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Author Closing Comment

by:bkreynolds48
ID: 35197759
Thanks and sorry for the delay my car engine blew yesterday while I was out of town.
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