| From: | Joshua Tolley <eggyknap(at)gmail(dot)com> |
|---|---|
| To: | Eric Schwarzenbach <Eric(dot)J(dot)Schwarzenbach(dot)C88(at)alumni(dot)upenn(dot)edu> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: [Fwd: Re: GEQO randomness?] |
| Date: | 2008-11-05 11:30:02 |
| Message-ID: | 20081105113002.GB18367@polonium.part.net |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
On Fri, Oct 31, 2008 at 06:57:25PM -0400, Eric Schwarzenbach wrote:
>
> My problem with GEQO using a random number generator is that
> non-deterministic behavior is really hard to debug, and problems can go
> undiagnosed for ages. Frankly I would rather something fail all the
> time, than it work most of the time and fail just now and then. Never
> getting a good plan for a query would be an improvement because I would
> immediately be aware there's a problem and be forced to something about
> it, as opposed to maybe realizing there is going to *sometimes* be a
> problem.
Randomness is an integral part of all kinds of algorithms designed to
solve really hard problems in reasonable time, like GEQO. Such
algorithms show up all the time in data modeling and optimization
problems.
- Josh / eggyknap
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