Re: *_collapse_limit, geqo_threshold

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От Kenneth Marshall
Тема Re: *_collapse_limit, geqo_threshold
Дата
Msg-id 20090708221415.GM22588@it.is.rice.edu
обсуждение исходный текст
Ответ на Re: *_collapse_limit, geqo_threshold  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Wed, Jul 08, 2009 at 05:46:02PM -0400, Tom Lane wrote:
> "Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> > For a moment it seemed logical to suggest a session GUC for the seed,
> > so if you got a bad plan you could keep rolling the dice until you got
> > one you liked; but my right-brain kept sending shivers down my spine
> > to suggest just how uncomfortable it was with that idea....
> 
> If memory serves, we actually had exactly that at some point.  But I
> think the reason it got taken out was that it interfered with the
> behavior of the random() function for everything else.  We'd have to
> give GEQO its own private random number generator.
> 
>             regards, tom lane
> 
A separate random number generator for GECO make a lot of sense.

Cheers,
Ken


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