| From: | "Brendan Jurd" <direvus(at)gmail(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Richard Huxton" <dev(at)archonet(dot)com>, "Sergey Konoplev" <gray(dot)ru(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [GENERAL] Very slow queries w/ NOT IN preparation (seems like a bug, test case) |
| Date: | 2008-11-12 18:03:41 |
| Message-ID: | 37ed240d0811121003v50f5f894v9973f18f5b986f03@mail.gmail.com |
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| Lists: | pgsql-general pgsql-hackers |
On Thu, Nov 13, 2008 at 4:52 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Yeah. An example of a closely related expression that it *would* be
> able to prove self-contradictory is
> WHERE x = ALL (ARRAY[1, 2, ...])
> or perhaps slightly more realistically
> WHERE x = ANY (ARRAY[1, 2, 3]) AND x > 4
It seems like the cure is worse than the disease here. Surely a user
who has a self-contradictory clause will realise the problem pretty
quickly (i.e., when he receives zero rows) and then just fix it.
I guess my question is, what's the real benefit of going to all this
trouble trying to prove that clauses are false? What real-world
problem does it address?
Cheers,
BJ
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