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Re: generalizing the planner knobs

From: "Pollard, Mike" <mpollard(at)cincom(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Greg Stark" <gsstark(at)mit(dot)edu>
Cc: "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>,"Neil Conway" <neilc(at)samurai(dot)com>,"pgsql-hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: generalizing the planner knobs
Date: 2005-12-01 21:14:11
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
Greg Stark <gsstark(at)mit(dot)edu> writes:
> On the other hand the type I would prefer to see are hints that feed
> into filling in information the planner lacks. This only requires that
> user understand his own data and still lets the planner pick the best
> based on the provided information.

Optimizer hints were added because some databases just don't have a very
smart optimizer.  But you are much better served tracking down cases in
which the optimizer makes a bad choice, and teaching the optimizer how
to make a better one.  That way, all users get the benefit of the fix.
Remember, the purpose of SQL is to isolate the end user from having to
care about how the data is retrieved; that is the RDBMS' problem.  (the
other thing forgotten was that it was supposed to be a natural language.
NVL.  Bah.)

Mike Pollard
SUPRA Server SQL Engineering and Support
Cincom Systems, Inc.


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