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Re: to undo or not to undo

From: Kirtikumar Deshpande <kirtikumar_deshpande_at_yahoo.com>
Date: Wed, 25 Feb 2004 10:31:06 -0800 (PST)
Message-ID: <20040225183107.63014.qmail@web9505.mail.yahoo.com>


Barbara,
  I always kept these activities separate.   Migrate to 9i first.
  Keep the old RBS after migrating to 9i for a new days, monitored them using v$transaction, v$rollstat to assist in sizing of undo tablespace and scheduled downtime to do:

  1. Remove old rbs, and associated tablespace(s).
  2. Create undo tablespace
  3. Change init.ora file And then restart the DB. This way all the new undo segments will start from USN # 1. I just prefer it that way to avoid any confusion (in the minds of my backup DBAs as to what happened to USN #1-40, for example).
  4. Monitor undo usage, and adjust undo_retention for just a few hours, at most, and then adjust the undo tablespace size. I have not had any problems. But again we do not have a tonne of (thousands of) concurrent transactions. Dan Fink has some horror stories when # of xactions reaches very high...

 Thanks for the kind words about my presentation at RMOUG..

 Regards,


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Received on Wed Feb 25 2004 - 12:28:02 CST

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