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RE: Big SGA.......

From: Loughmiller, Greg <Greg.Loughmiller_at_cingular.com>
Date: Mon, 03 Mar 2003 13:28:53 -0800
Message-ID: <F001.0055EEF5.20030303132853@fatcity.com>


one little piece of information..(considered critical probably:-) )  

There isn't an opportunity to use statspack... The current application is running on sybase:-)  

I do have other teams researching the questions you mention. its a real fun project...

-----Original Message-----
Sent: Monday, March 03, 2003 2:02 PM
To: Multiple recipients of list ORACLE-L

Please start using STATSPACK now to gather and keep statistics. You are certainly going to need "before" and "after" statistics to analyze.  

Some questions:

Gathering STATSPACK data and searching for the SQL statements generating the largest number of "physical I/O" requests might be illuminating for the developers. If you work with them on a one-by-one basis on tuning each of these SQL statements, you might see dramatic improvements in performance.  

Suggest to them that *after* you are confident that there are no tunable SQL statements, then you might consider increasing the size of the Buffer Cache. Doing so is a last resort, not a first response. This is because doing so does not fix the real problem, it only accomodates the real problem, which is inefficient SQL.  

Hope this helps...  

-Tim

hey folks.. Hoping for a little feedback and opinion please. Having a discussion with the development group ...  

The development group is thinking that a VERY LARGE SGA would solve some of their I/O problems. For example, they believe that a SGA consisting of over 8GB of db block buffers would resolve their multitude of issues. I feel that they open another can of worms with something such as this.. And granted-there hasn't really been an infrastructure evaluation-and the SA group is currently performing that review of the environment.  

One could suggest that they could "cache" some very large tables in the SGA; but there seems to be some sense of a down side to this.. Could you all provide some input on "Extremely large SGA's"? In the area of 8GB or so.. BUT, most of this would be the database blocks. Would you all be so kinds to provide your thoughts please?
TIA     Greg Loughmiller
Sr Manager - Enterprise Data Architecture gloughmiller (IPS)
678.893.3217 (office)  

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Author: Loughmiller, Greg
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Received on Mon Mar 03 2003 - 15:28:53 CST

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