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Re: consistency in cost?

From: Jared Still <>
Date: Tue, 08 May 2001 10:03:07 -0700
Message-ID: <>


I've run into the same problem in the past.

Export a database to a different machine with a significantly different configuration, and you will get different execution paths.

I was never successfull in getting the correct excution plans via database parameters. The solution was to use hints in the SQL to correct the problem.

A TAR was opened on this problem, and Oracle support informed me of the above information.


On Tuesday 08 May 2001 08:32, Henry Poras wrote:
> 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-----
> From: Jared Still []
> Sent: Tuesday, May 08, 2001 12:56 AM
> To:; Henry Poras
> Subject: Re: consistency in cost?
> 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:
Author: Jared Still

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Received on Tue May 08 2001 - 12:03:07 CDT

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