RE: ASMM

From: Jeffrey Beckstrom <JBECKSTROM_at_gcrta.org>
Date: Mon, 12 May 2014 11:30:26 -0400
Message-Id: <5370B0D20200000B00521D8A_at_groupwise.gcrta.org>

Since you have a lot of SQL with liternals, you will have a low hit ratio no matter how much memory you add to it.

Jeffrey Beckstrom
Database Administrator
Information Systems
Greater Cleveland Regional Transit Authority 1240 W. 6th Street
Cleveland, Ohio 44113

>>> "Zelli, Brian" <Brian.Zelli_at_RoswellPark.org> 5/12/14 11:09 AM >>>

Fixed SGA Size				   2.07003021
Redo Buffers					 6.41796875
Buffer Cache Size					   592
Shared Pool Size			 		   464
Large Pool Size						  16
Java Pool Size						   16
Streams Pool Size						 0
Shared IO Pool Size					   0
Granule Size							 16
Maximum SGA Size	 			1672.48828
Startup overhead in Shared Pool		 192
 
NAME							    SIZE_MB
-------------------------------- ----------
Free SGA Memory Available			   576
 

Is the results of the query. It is a mix and there are a lot of SQL with literals.  

Brian    

From: Chris Taylor [mailto:christopherdtaylor1994_at_gmail.com] Sent: Monday, May 12, 2014 10:56 AM
To: Zelli, Brian
Cc: oracle-l_at_freelists.org
Subject: Re: ASMM  

First I would caution you on the use of trying to hit some "magical" ratio - there are lots of discussions on this topic both on this list and around the web (AskTom, Hotsos, Cary Millsap etc)

Here's a link to a 2003 article at Hotsos:  

http://www.hotsos.com/e-library/abstract.php?id=6  

​Now, having said that, what _are_ your pool sizes currently?  

select name,bytes/1024/1024 as size_mb

 from v$sgainfo

 /  

Next, what is your application profile "look like"? What I mean by that is, for the applications that use your database, what does the app do inside the database? Is it a lot of straight SQL? A lot of PL/SQL? A mix? Does the SQL and PL/SQL use bind variables appropriately, or do you have lots of SQL with literal values that are considered "unique"?  

If you have a lot of SQL that cannot be shared, this is going to drive down that ratio you're looking at. Also if you have anything that is flooding the library cache and invalidating previous SQL that will also drive down your ration I believe. And there are others as well.  

Regards,

Chris    

On Mon, May 12, 2014 at 9:41 AM, Zelli, Brian <Brian.Zelli_at_roswellpark.org> wrote:

I am finding that my Library Cache Get hit Ratio % is hovering around 50-60 percent. I read that the value should be above 90%. I read that the recommendation is to increase the shared pool size. I am running AMM and I set the memory_target twice what it was and still no relief…..    

Brian    

From: Chris Taylor [mailto:christopherdtaylor1994_at_gmail.com] Sent: Monday, May 12, 2014 10:38 AM
To: Zelli, Brian
Cc: oracle-l (oracle-l_at_freelists.org) Subject: Re: ASMM  

Brian,  

The answer to your question is "it depends". What are you running now?  (AMM I assume?) What is your goal? Are you trying to solve a problem you think is related to AMM or a non-AMM configuration? There's not a black and white answer to your question. With some more details people "might" be able to offer some insight/suggestions.  

Regards,

Chris  

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Received on Mon May 12 2014 - 17:30:26 CEST