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Re: Shared Pool vs Buffer Cache with ASMM

From: fairlie rego <>
Date: Fri, 6 Jul 2007 04:47:11 -0700 (PDT)
Message-ID: <>


  The default algorithm of ASSM is that memory is stolen from the buffer cache if the shared pool is stressed. However this default behaviour can be changed by setting _memory_broker_shrink_heaps=30 The default value for the above parameter is 0   

If you want to continue using this feature you might want to set a minimum value for your buffer cache so that memory does not shrink to below this value.    


Richard Saints <> wrote:      

  Hello to you all,
  I've a mobile application that uses Oracle Lite 10g ( as mobile server and Oracle Database Server 10g release 1 ( as the repository database. Both of these components are installed on servers with Microsoft Windows 2000 Advanced Server.    

  My question is related with the repository database:   We use Automatic Shared Memory Management and have a SGA target = to the SGA Max Size = 1336Mb. ASMM always gave a bigger slice of memory to the Buffer Cache (about 70%), but in the last 2 weeks I noticed that the value of the Shared Pool started to increase and now it's bigger than Buffer Cache (a slice of 49,7%).   Here's my current situation:
  Shared Pool 664 Mb
  Buffer Cache 648 Mb
  Large Pool 8 Mb
  Java Pool 8 Mb
  Other 8 Mb    

  I have some knowledge of Oracle Database Server Architecture, but I'm being able to interpret this behavior or why this is happening. Can anyone give me some help or some ideas ?    

  It's also important to say that we have been experiencing some performance problems in the last two weeks. We are also having a bigger volume of data.        

  Thanks for all your attention.    

  Best Regards,
  Ricardo Santos
  PL/SQL Analyst/Developer    

          Fairlie Rego
Senior Oracle Consultant
  M: +61 402 792 405            

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-- Received on Fri Jul 06 2007 - 06:47:11 CDT

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