RE: Query processing takes very variable time

Sorry, I am not a DBA and was trying to get help for in-house DBAs while they find the reason.  

It is Oracle 10.2.0.4 on Solaris platform with a 2-node RAC (though shutting down and making it single-node also gives the same problem). We don't see problem with first query only. It is intermittent. The shared storage is SUN-StorEdge3320.  

However, one thing they are looking at is related to Oracle HWM.  

I will update with more details once we resolve this.  

Thanks for all the help.  

• Pradeep

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From: David Barbour [mailto:david.barbour1_at_gmail.com] Sent: Tuesday, December 30, 2008 12:56 PM To: oracledba.williams_at_gmail.com
Cc: Pradeep Chetal; Jared Still; oracle-l_at_freelists.org Subject: Re: Query processing takes very variable time  

It might help if we knew the version of Oracle and the Operating System at a minimum. Since we're tossing about WAGS, why not check to make sure the optimizer settings on both instances are identical?

On Tue, Dec 30, 2008 at 11:06 AM, Dennis Williams
<oracledba.williams_at_gmail.com> wrote:

Pradeep,  

As others have pointed out, there can be many reasons for erratic behavior.  

Here is my personal favorite. If you are using bind variables, the first time the statement is parsed, an execution plan is created, and all subsequent executions use that plan. So, suppose after the database is bounced, the first execution has bind variables that causes an unusual execution plan. All future executions will get that plan. Nice.  

Dennis Williams

On Mon, Dec 29, 2008 at 6:53 PM, Pradeep Chetal
<Pradeep.Chetal_at_mformation.com> wrote:
 

Sorry, Jared for the cryptic request. It is a complex process to set up the tables, etc, but once they are set, we run a stored proc that works on these tables - and the SQL code seems very simple - selects, inserts, and updates [even those are simple, nothing fancy ]. However, the processing factor takes long sometimes (not all the times).  

I was hoping to look for *extraneous* factors (outside the code) that can affect the processing and if anyone on this list has any experience like that.  

Thanks,  

• Pradeep

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From: Jared Still [mailto:jkstill_at_gmail.com] Sent: Monday, December 29, 2008 3:17 PM
To: Pradeep Chetal
Cc: oracle-l_at_freelists.org
Subject: Re: Query processing takes very variable time    

On Mon, Dec 29, 2008 at 5:46 AM, Pradeep Chetal
<Pradeep.Chetal_at_mformation.com> wrote:

Without going into complete details, has anyone on the list seen something like that? Any ideas.

Without going into complete explanations, yes.

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist               

Pradeep Chetal
Sr. Director - Infrastructure Architecture

Mformation Technologies Inc.
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