Re: Why does _no_or_expansion affect Execute time rather than Parse time?
- From: Mladen Gogala <gogala@xxxxxxxxxxxxx>
- To: joseph.m.coffey@xxxxxxxxxxxxx
- Date: Wed, 16 Aug 2006 17:47:06 -0400
On 08/16/2006 05:07:14 PM, joseph.m.coffey@xxxxxxxxxxxxx wrote:
>
> My question is - why was this time reported as Execute rather than
> Parse? Shouldn't the contemplation of what plan to run be considered
> parsing - and then actually executing the plan be executing? Wouldn't
> or expansion be part of contemplating what plan to run?
Joe, _NO_OR_EXPANSION has been a little dirty secret of some data warehousing
guys to
force the star schema execution plan. There are quite a few bugs related to
this parameter
and the latest bug related to it is 5458691. This is a 10.2.0.2 bug causing PGA
to spiral
out of control when this parameter is set. There is a reason for this parameter
to remain
undocumented. Siebel shouldn't use that without very valid reason. Ensuring
that you have
all the statistics and all the histograms that your queries need will be more
useful then
black magic with the undocumented parameters. Creating dimension objects for
all your dimension
tables will get you the desired star queries in a much more painless way.
--
Mladen Gogala
http://www.mgogala.com
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