Re: Query processing takes very variable time
Date: Tue, 30 Dec 2008 10:02:36 -0800 (PST)
Message-ID: <162529.13159.qm@web38906.mail.mud.yahoo.com>
Reminds me of an episode of House... Patient comes in with a wide collection of odd symptoms... patient is unconscious so they can't get any real medical history... the result is a massive throwing out of ideas and eliminating them one by one based on the symptoms. Differential diagnosis.... Actually kind of fun in the database world if you are not under the gun to fix something. :-)
RF
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From: David Barbour <david.barbour1_at_gmail.com> To: oracledba.williams_at_gmail.com
Cc: Pradeep.Chetal_at_mformation.com; Jared Still <jkstill_at_gmail.com>; oracle-l_at_freelists.org Sent: Tuesday, December 30, 2008 10:56:25 AM 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
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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