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RE: any single serial session will never get more than 5% of pga

From: Khedr, Waleed <Waleed.Khedr_at_FMR.COM>
Date: Fri, 26 Dec 2003 15:39:25 -0800
Message-ID: <F001.005DB1B4.20031226153925@fatcity.com>


To be honest I'm not sure why such a <feature> is available! I have not used it so I'm not really qualified enough to judge it.

But in my opinion, a session asks for memory because it needs memory. So is it possible that a session is asking for memory that it does not really need and it can continue running without the requested memory? The answer could be yes, if the more memory means faster (like sorting) and the sort_area_size is too big to be satisfied for all sessions, in this situation the DBA is responsible for the wrong settings.

But what if more memory is required like: memory tables, associative arrays, etc and memory was denied? Would the session fail? I think the answer would be "YES" - Did anybody try this?

Is the feature available because Oracle sessions don't deallocate the extra memory and by using this feature, it will encourage the sessions that already succeeded in allocating memory that they don't need any more by punishing the ones that ask for more memory now by saying "NO"? Or is it going to ask the sessions that have extra allocated memory to release it which should be the normal behavior anyway without using any policies?

Regards,

Waleed

-----Original Message-----
Sent: Friday, December 26, 2003 5:39 PM
To: Multiple recipients of list ORACLE-L pga_aggregate_target

For special cases like that I would switch the session back to a manual workarea policy and set a suitable sort area.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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  who can answer the questions, but the
  person who can question the answers -- T. Schick Jr

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> Is there any way to give say 75% of pga_aggregate_target
> to a single session? The reason I am asking this is -
> sometimes we need to build an index as soon as possible
> and the index creating is the only thing running and
> other applications are stopped waiting for the index.
>
> Thanks,
>
> Roger

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Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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Received on Fri Dec 26 2003 - 17:39:25 CST

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