RE: cost
- From: Riyaj Shamsudeen <rshamsud@xxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 05 Apr 2004 12:59:33 -0500
*I think*, this is due to optimizer heuristics . First_rows cost model
is implemented as an heuristics model and applied over the usual cost
comparisons. I have seen optimizer choose a costlier plan because this
heuristics was/was not applied.
I wonder what results you would get if you have optimizer_mode set to
first_rows in your test case ?
Thanks
Riyaj "Re-yas" Shamsudeen
Certified Oracle DBA
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Cary Millsap
Sent: Monday, April 05, 2004 12:35 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: cost
Yep, "bug" is where we're going with it... But we haven't had time yet
to go into detail.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Bobak, Mark
Sent: Monday, April 05, 2004 12:24 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: cost
Hmm....I should have known, Cary...;-)
I actually had the thought, as I was typing that reply "hmm....*always*,
really? Are you sure? Yeah, of course you are, if it's not always
choosing the lowest cost, what else could it do....?" Of course, Oracle
found a way.....
My first thought, though, would be that this is a bug.....is that where
you're going with this? Or is there something more going on? Did 10053
reveal anything interesting?
-Mark
Mark J. Bobak
Oracle DBA
ProQuest Company
Ann Arbor, MI
"Post Hoc Ergo Propter Hoc"
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