RE: Do you use KEEP Buffer Pool in your production system?
- From: Martin Brown <martinfbrown@xxxxxxxxxxx>
- To: <elkinsl@xxxxxxxxx>, <kamusis@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 26 Mar 2010 13:42:12 -0400
Just a simple question here. We use a 8-node rac cluster and each instance
would require its own keep pool. What I have read and my very basic understand
implies that using the keep pool would impede performance. Am I wrong about
that?
From: elkinsl@xxxxxxxxx
To: kamusis@xxxxxxxxx; Oracle-L@xxxxxxxxxxxxx
Subject: RE: Do you use KEEP Buffer Pool in your production system?
Date: Fri, 26 Mar 2010 09:41:43 -0500
We’ve used once for a vendor application and DB, but it was *far* down the
priority list after addressing other items that provided much bigger bang for
the buck. The targeted on-line business critical processes did indeed improve,
marginally, but enough to be noticed and appreciated, while some of the less
important, response time perspective, processes saw a slight degradation. The
impact was measured and quantified. Used a combination of all three pools, with
those huge segments “polluting” the pool assigned to RECYCLE and letting them
duke it out there, more critical segments in KEEP, and everything else in the
DEFAULT. Once again, only done after bigger bang for the buck things were
addressed, including why are you *hitting* those segments so frequently.
With a new version of the vendor software and an upgrade to the DB about to
roll out, we are going back to strictly DEFAULT and will re-consider if things
point to it possibly helping. And as Mark alluded to, over time it has become
un-tuned somewhat and not quite providing the initial gains that were seen.
Larry G. Elkins
Refer to AskTom:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1590999000346302363
Tom Kyte said:
I would not use the keep pool, the default buffer cache is almost certainly
better than good enough.
The keep buffer would definitely be in the SGA, it is just another buffer
cache.
What do you think? Do you use KEEP Buffer Pool in your production system?
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