RE: Explain plan accuracy and bind variables

From: Vergara, Michael (TEM) <mvergara_at_guidant.com>
Date: Fri, 6 Feb 2004 08:19:10 -0800
Message-ID: <791D0E1ECDECD04D89205F33806FC38701E91B48@temmse06.tem.guidant.com>

Cary, et al:

Is this documented somewhere? I run an SAP shop, and I have ABAP'ers who swear that the v9 CBO is buggy because a pre-execution plan and a post-execution plan don't necessarily match, and=20 our performance-problem meetings are turning into shouting matches.

Thanks,
Mike

-----Original Message-----
From: Cary Millsap [mailto:cary.millsap_at_hotsos.com] Sent: Friday, February 06, 2004 7:32 AM
To: oracle-l_at_freelists.org
Subject: RE: Explain plan accuracy and bind variables

It means "wrong plan." Different row source operations which aren't what Oracle would really do if you were to run the query.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

Upcoming events:
- Performance Diagnosis 101: 2/24 San Diego, 3/23 Park City, 4/6 Seattle

SQL Optimization 101: 2/16 Dallas
Hotsos Symposium 2004: March 7-10 Dallas
Visit www.hotsos.com for schedule details...

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Khedr, Waleed Sent: Friday, February 06, 2004 9:18 AM
To: 'oracle-l_at_freelists.org'
Subject: RE: Explain plan accuracy and bind variables

How do you define inaccurate?

Waleed

-----Original Message-----
From: ryan.gaffuri_at_cox.net [mailto:ryan.gaffuri_at_cox.net] Sent: Friday, February 06, 2004 7:38 AM
To: oracle-l_at_freelists.org
Subject: Explain plan accuracy and bind variables

I read somewhere that explain plans are not always accurate. Does this include autotrace? What about if I do a 10046 or just a sql_trace?=20

Are explain plans more apt to be inaccurate with bind variables(I think I
read that somewhere). If so, why?=20

Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.

--
Archives are at http://www.freelists.org/archives/oracle-l/
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html
-----------------------------------------------------------------

Received on Fri Feb 06 2004 - 10:19:10 CST