Re: Auto stats gathering is not sufficient - what now?

From: Greg Rahn <greg_at_structureddata.org>
Date: Thu, 10 Feb 2011 09:31:48 -0800
Message-ID: <AANLkTimH6jsrcx_=MZLNoZnvTuvK3DmPg-ABKFgc-3d+_at_mail.gmail.com>

I would advise against that. Dynamic Sampling (DS) does not have the same information that you get from dbms_stats.

"The most common misconception is that DS can be used as a substitute for optimizer statistics." 2nd sentence from http://blogs.oracle.com/optimizer/2010/08/dynamic_sampling_and_its_impact_on_the_optimizer.html

On Thu, Feb 10, 2011 at 12:16 AM, David Aldridge <david_at_david-aldridge.com> wrote:
> You could consider not gathering statistics at all -- delete current
> statistics and lock the table statistics -- and rely on dynamic sampling.
> The usual duration of reporting queries against large tables, particularly
> the consequences for the duration if the execution plan is incorrect,
> generally make the dynamic sampling overhead acceptable.

-- 
Regards,
Greg Rahn
http://structureddata.org
--
http://www.freelists.org/webpage/oracle-l

Received on Thu Feb 10 2011 - 11:31:48 CST