Re: Sub-pools

From: Stefan Koehler <contact_at_soocs.de>
Date: Fri, 28 Aug 2015 21:32:04 +0200 (CEST)
Message-ID: <1377798474.46140.1440790324456.JavaMail.open-xchange_at_app02.ox.hosteurope.de>



Hi Michael,
the value is calculated at startup (mostly based on CPU_COUNT and SHARED_POOL_SIZE). Why do you want to change it?

In the first code versions (started with 9i) there was a design flaw, that a process gonna request memory from just one sub-pool and if not enough contiguous free memory was available in that sub-pool you received an ORA-04031, even if there were enough available chunks in the other sub-pools. But this has improved a lot - so usually no need to fiddle with this parameter (e.g. like setting it to 1).

However the maximum are 7 sub-pools (as protected by 7 separate shared pool latches). Some time ago i asked Tanel about the mapping of the latches and sub-pools - details can be found in this Tweet: https://twitter.com/OracleSK/status/595909279481274368

Finally don't forget about the durations. The amount/usage of durations also has changed with Oracle 12c - for details please check this blog post: https://mahmoudhatem.wordpress.com/2015/04/22/oracle-12c-shared-pool-and-durations-enhancement/  

Best Regards
Stefan Koehler

Freelance Oracle performance consultant and researcher Homepage: http://www.soocs.de
Twitter: _at_OracleSK  

> Michael Calisi <oracle455_at_gmail.com> hat am 28. August 2015 um 20:21 geschrieben:
>
> How many subpools do you have as a default ?
>
> _kghdsidx_count"= Wondering what's the best way to determine setting this parameter running Oracle 11.2.0.4.0
 

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Received on Fri Aug 28 2015 - 21:32:04 CEST

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