Re: Urgent rac wait problem

From: Riyaj Shamsudeen <riyaj.shamsudeen_at_gmail.com>
Date: Mon, 16 Mar 2009 10:02:14 -0500
Message-ID: <203315c10903160802s96feac4u7f4322aa8dd10488_at_mail.gmail.com>

Hi Adar
  Of course, that makes sense :-)

   PGA_Aggregate_target plays important role in SORT calculations. If that value is set lower in one instance, then execution plan can be very different between instances, at least, that was the case with a recent customer issue.

   I had few of those adventures and mostly boils down to PGAT differences. Differences in few other parameters can matter too.

-- 
Cheers

Riyaj Shamsudeen
Principal DBA,
Ora!nternals -  http://www.orainternals.com
Specialists in Performance, Recovery and EBS11i
Blog: http://orainternals.wordpress.com

On Mon, Mar 16, 2009 at 4:50 AM, Yechiel Adar <adar666_at_inter.net.il> wrote:



> Since this is the only difference between the servers,

> I think that the number of cpus and the memory size may be a factor in the

> optimizer calculations.

> In the server with fewer resources oracle choose another path that needed a

> lot more blocks,

> but used less online memory, and caused a lot more gc 2-way wait.

> I never delved deep into the optimizer.

>

> Adar Yechiel

> Rechovot, Israel

>

>

>

> Dion Cho wrote:

>

>> You solved your problem by updating the statistics.

>>

>> Why on the earth do you think that CPU count and physical memory size were

>> the reasons?

>>

>> ================================

>> Dion Cho - Oracle Performance Storyteller

>>

>> http://dioncho.wordpress.com (english)

>> http://ukja.tistory.com (korean)

>> ================================

>>

>>

>>  --

>

> http://www.freelists.org/webpage/oracle-l

>

>

>


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Received on Mon Mar 16 2009 - 10:02:14 CDT