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Re: consistency in cost?

From: Bambi Bellows <ultrageek_at_techie.com>
Date: Wed, 09 May 2001 17:36:24 -0700
Message-ID: <F001.002FE83D.20010509143100@fatcity.com>

Tim --

Oh, sure, bring LOGIC into it. Truth of the matter is that Oracle is trying to phase out the last vestiges of v5, and that's never EVER going to happen. Logic be dammed! Mwahahahaha!

Bambi.

------Original Message-----
Date: Wed, 09 May 2001 05:01:06 -0800
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>

> Interesting...CHOOSE means Oracle will decide whether to use RULE or COST. But a
>CHOOSE hint will force use of COST. Kind of diminishes the meaning of CHOOSE,
>doesn't it? Seems like a pointless hint...
>
> >>> rabbit_at_emirates.net.ae 05/08/01 11:45PM >>>
> If the system is Rule based and you code Hints, the CBO will be
> automatically invoked
> Sam
>
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Tuesday, May 08, 2001 10:12 PM
>
>
> > Forgive my ignorance but I thought hints were only for cost based
> optimizer.
> >
> >
> > Have you checked in case anybody has changed any parameters while the
> system
> > is running as I know that changing the hash_area_size can change the
> > execution plan?. Are you using parallelism as if a table had to be
> > recreated for any reason and its degree changed it might do a FTS?
> >
> > Cheers
> >
> > Iain Nicoll
> >
> >
> > -----Original Message-----
> > Sent: 08 May 2001 17:31
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Jared,
> > The only difference is about a weeks worth of extra data. Well, the
> hardware
> > is also different (Ultra450 vs. Ultra 5000. Also 1 vs 4 CPU). But
> > regardless, shouldn't init.ora optimizer_mode=choose be identical to
> > optimizer_mode=rule with hint=choose? If I have the time, I'll try to set
> up
> > a couple of systems and examine by moving stats and taking some 10053
> dumps.
> > (one of the ones giving me a problem is in production so I have limited
> play
> > time there).
> >
> > Henry
> >
> > -----Original Message-----
> > Sent: Tuesday, May 08, 2001 12:56 AM
> > To: ORACLE-L_at_fatcity.com; Henry Poras
> >
> >
> >
> > Henry,
> >
> > You say 'nearly identical'.
> >
> > What are the differences?
> >
> > Are the 2 databases on the same platform?
> >
> > If not, what are the differences, hardware and OS?
> >
> > Jared
> >
> >
> > On Monday 07 May 2001 21:55, Henry Poras wrote:
> > > I am working with an 8.1.6 database on Solaris 2.6 and I am wondering if
> > > there is any consistency in the optimizer. We have two nearly identical
> > > databases (one a clone from two weeks ago). A five table join has nearly
> > > the identical execution plan on the two databases. The difference is in
> > the
> > > access method of the fourth table in the join; in one case it is
> accessed
> > > by a FTS and in the other, by Index. This difference has a large effect
> on
> > > performance. Statistics are nearly identical for this table in both
> > > databases (I looked at dba_tables, dba_indexes, dba_col_tables). Also,
> the
> > > init.ora is the same. When I changed the optimizer_mode to rule and
> added
> > a
> > > 'choose' hint to the query, the execution plan was different again. I
> will
> > > look into this a bit further and post my results. Just wondering about
> > > other's experiences. Thanks.
> > >
> > > Henry
> > --
> > Please see the official ORACLE-L FAQ: <A HREF="http://www.orafaq.com"
>TARGET="_new"><FONT COLOR="BLUE">http://www.orafaq.com</FONT></A>
> > --
> > Author: Henry Poras
> > INET: Henry.Poras_at_ctp.com
> >
> > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> > San Diego, California -- Public Internet access / Mailing Lists
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> > --
> > Please see the official ORACLE-L FAQ: <A HREF="http://www.orafaq.com"
>TARGET="_new"><FONT COLOR="BLUE">http://www.orafaq.com</FONT></A>
> > --
> > Author: Nicoll, Iain (Calanais)
> > INET: iain.nicoll_at_calanais.com
> >
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> > San Diego, California -- Public Internet access / Mailing Lists
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> --
> Please see the official ORACLE-L FAQ: <A HREF="http://www.orafaq.com"
>TARGET="_new"><FONT COLOR="BLUE">http://www.orafaq.com</FONT></A>
> --
> Author: Sam Roberts
> INET: rabbit_at_emirates.net.ae
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
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> --
> Please see the official ORACLE-L FAQ: <A HREF="http://www.orafaq.com"
>TARGET="_new"><FONT COLOR="BLUE">http://www.orafaq.com</FONT></A>
> --
> Author: Tim Sawmiller
> INET: sawmillert_at_state.mi.us
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
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-- 

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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Bambi Bellows
  INET: ultrageek_at_techie.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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Received on Wed May 09 2001 - 19:36:24 CDT

Original text of this message

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