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Re: Very Strange Query Access Plan

From: Greg Rahn <greg_at_structureddata.org>
Date: Tue, 2 Oct 2007 12:31:45 -0700
Message-ID: <a9c093440710021231t409dd3depb6c42627fb8eba7a@mail.gmail.com>


Few questions:
Can you elaborate on the "bad" values? What makes them bad? Are other values (like NDV) non-representative as well? What is your DBMS_STATS.GATHER_* command?

The reason I am asking is I'd like to understand if this was a symptom of a suboptimal DBMS_STATS gather process (meaning non-default options), or if it is more to do with DBMS_STATS itself (using default options).

Also sharing your debug approach would be beneficial for the community. Often times its more about the approach to solving the issue rather than the solution itself.

On 10/2/07, Mercadante, Thomas F (LABOR) <Thomas.Mercadante_at_labor.state.ny.us> wrote:

> Thanks to Alvaro Jose Fernandez & Ric Van Dyke, this is solved. The DENSITY
> and CLUSTER FACTOR values in the user_tab_columns for my database table had
> bad values. These values are calculated by the DBMS_STATS package. I
> manually set these to a much lower figure and my problem went away.

-- 
Regards,

Greg Rahn
http://structureddata.org
--
http://www.freelists.org/webpage/oracle-l
Received on Tue Oct 02 2007 - 14:31:45 CDT

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