From: | Andrew Sullivan <ajs(at)crankycanuck(dot)ca> |
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To: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: pg, mysql comparison with "group by" clause |
Date: | 2005-10-13 18:43:03 |
Message-ID: | 20051013184303.GQ16317@phlogiston.dyndns.org |
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Lists: | pgsql-sql |
On Thu, Oct 13, 2005 at 02:26:58PM -0400, Greg Stark wrote:
> Scott Marlowe <smarlowe(at)g2switchworks(dot)com> writes:
> > could run this query at the same time and get different data from the
> > same set and the same point in time.
>
> I'm pretty unsympathetic to the "we should make a language less powerful and
> more awkward because someone might use it wrong" argument.
That's not what Scott's saying. Scott is saying that the syntax
you're talking about is _formally wrong_. That's surely not "more
powerful", except in the sense that stepping on a land mine is more
powerful than many other ways you could shoot yourself in the foot.
> path. In an ideal world the user should be guaranteed that
> equivalent queries would always result in the same plan regardless
> of how they're written.
And again, I say it sounds like you're actually arguing for "the
optimiser needs to get better". Special-purpose, formally wrong
syntax is surely not better than making the optimiser get the right
syntax right every time, is it?
A
--
Andrew Sullivan | ajs(at)crankycanuck(dot)ca
When my information changes, I alter my conclusions. What do you do sir?
--attr. John Maynard Keynes
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