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Home -> Community -> Mailing Lists -> Oracle-L -> RE: oracle can ignore hints
It's "later."
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *
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-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Lim, Binley
Sent: Sunday, March 07, 2004 8:44 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: oracle can ignore hints
IIRC, RBO had that thing where in the event of an index-tie (2 indexes qualify equally according to the rules), the index with a later creation date(or is it earlier?) is picked.
> -----Original Message-----
> From: Jared Still [SMTP:jkstill_at_cybcon.com]
> Sent: Saturday, March 06, 2004 3:58 AM
> To: Oracle-L Freelists
> Subject: Re: oracle can ignore hints
>
> I have had that exact same experience.
>
> Two Sun servers, different number of CPU's and RAM,
> same versions of Oracle 7 down to the patch level,
> data exported from one database into the other.
>
> Strictly RBO, two very different execution paths.
>
> Very frustrating, wish I could recall the solution we used.
>
> Jared
>
>
>
>
> On Fri, 2004-03-05 at 00:41, Kresimir Fabijanic wrote:
> > Hi Ryan
> >
> > What version of Oracle and OS are you running? What hint did you
try to
>
> > use? How complex was query?
> >
> > I have seen a case (OK it was 7.3.4.0 in 1999 on Sun's OS) where two
> > databases - same version, same OS same Oracle and OS patches on both
-
> > hardware configuration was slightly different (not 100% sure but
there
> > were differences in RAM (1G vs 2G or 4G) and number of CPUs - (2 vs
4)
> > and some disk layout differences) both databases running RULE
(software
> > vendor requested [Keystone - if you have ever heard of it]) -
identical
> > statement (cut and paste between two terminal sessions (and back))
> > generating very different execution plans.
> >
> > I tried to verify few times and results were consistently different.
> > Nothing would surprise me any more.
> >
> > Kind regards
> >
> > Kresimir Fabijanic
> >
> > ryan.gaffuri_at_cox.net wrote:
> >
> > >We had a discussion on here regarding hints. some of you stated
that
> Oracle cannot ignore a proper hint. I have a TAR open and asked about
> this. Here is the response.
> > >
> > >
> > >
> > >"A hint simply adds weight to a cost estimation, it can still be
> overridden by the CBO if the values aren't seen as useful."
> > >
> > >
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-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- 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 Sun Mar 07 2004 - 21:35:30 CST
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