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Re: Oracle 9i PGA Memory

From: Mladen Gogala <gogala_at_sbcglobal.net>
Date: Thu, 09 Feb 2006 05:41:22 GMT
Message-Id: <pan.2006.02.09.05.41.22.336880@sbcglobal.net>


On Wed, 08 Feb 2006 17:03:22 -0800, Michael42 wrote:

> 1. If my PGA and session related values appropriate?
> 2. What are some best practices on changing the related values for PGA
> and connections?

PGA is used primarily for sorts and hashes. V$SYSSTAT and V$SESSTAT have statistics that tell you how many sorts have gone to the disk and how many have not.
  1* select name from v$statname where lower(name) like '%sort%' SQL> / NAME


sorts (memory)
sorts (disk)
sorts (rows)

Unfortunately, nothing tells you how many hash operations have gone to disk. That is probably the most significant measure that Oracle misses right now. You will have to rely on V$PGASTAT which will tell you the maximum of PGA in use at any time. The common wisdom tells you that you don't want frequent memory adjustment operations to take place, sto that would be an ideal choice for the PGA aggregate target.

-- 
http://www.mgogala.com
Received on Wed Feb 08 2006 - 23:41:22 CST

Original text of this message

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