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Re: Optimizer hook

From: Julius Stroffek <Julius(dot)Stroffek(at)Sun(dot)COM>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Optimizer hook
Date: 2007-09-25 23:40:32
Message-ID: 46F99C70.50203@sun.com (view raw or flat)
Thread:
Lists: pgsql-patches
> Why would you care?  Seems like forcing that to not happen is actively
> making it stupider.
>   
To better compare the algorithms and possibly not for final solution at
the beginning. If we would implement 10 algorithms and want to pickup
just 3 best ones to be used and throw 7 away.

Later on, we can try to run just the one "very fast" algorithm and
depending on the cost decide whether we would run remaining 9 or
less or even none.

Yes, the example in dummy.c is really stupider, but it could be done
in more clever way.

> Well, I can see one likely problem: list_copy is a shallow copy and
> thus doesn't ensure that the second set of functions sees the same input
> data structures as the first.  I know that geqo has to go through some
> special pushups to perform multiple invocations of the base planner,
> and I suspect you need that here too.  Look at geqo_eval().

I'll explore that.

Thanks

Regards

Julius Stroffek


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