Re: performance question

From: Ron Crisco <ron.crisco_at_method-r.com>
Date: Tue, 13 Apr 2010 10:36:20 -0500
Message-ID: <y2r2c5e62d71004130836gb83e9cb0r43bcbe1545e14168_at_mail.gmail.com>

Rather than guessing, you can know the answer. Just run 10053 tracing in both instances and compare. To interpret the results, I highly recommend a paper written by Wolfgang Breitling, available at http://www.centrexcc.com/A%20Look%20under%20the%20Hood%20of%20CBO%20-%20the%2010053%20Event.pdf

Ron Crisco

On Tue, Apr 13, 2010 at 9:54 AM, Joan Hsieh <joan.hsieh_at_tufts.edu> wrote:

> Hi dear listers,
>
> I have a very strange performance issue which I couldn't figure it out.
> I have 2 11.2.0.1 databases with the exactly same parameters, they both on
> the same server. One sql statement run on both database generated 2 diff
> plans. So I exported the whole schema stats from the good db, imported it to
> the bad one. It didn't change the result. I can easily fix the performance
> issue on the bad db by setting optimizer_feature_enabled to 10g, but I just
> wondering why the 2 databases have different plans even after I imported the
> stats and checked the stats.
>
> Thanks,
>
> Joan
>
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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Received on Tue Apr 13 2010 - 10:36:20 CDT