To: Robert Haas <robertmhaas@gmail.com>
cc: Fabien COELHO <coelho@cri.ensmp.fr>,
	PostgreSQL Bugs List <pgsql-bugs@postgresql.org>
Subject: Re: issue about information_schema REFERENTIAL_CONSTRAINTS 
In-reply-to: <AANLkTin1vvc2Yfs3mBnmL_yCq3KRuMbo4zzGihsNcuQZ@mail.gmail.com> 
References: <alpine.DEB.2.00.1008311337530.2449@localhost.localdomain>
	<2683.1283266019@sss.pgh.pa.us>
	<AANLkTin1vvc2Yfs3mBnmL_yCq3KRuMbo4zzGihsNcuQZ@mail.gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Sat, 11 Sep 2010 20:24:55 -0400"
Date: Sun, 12 Sep 2010 00:40:32 -0400
Message-ID: <29605.1284266432@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Aug 31, 2010 at 10:46 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> We are not going to try to enforce uniqueness.  This has been debated
>> before, and most people like the current behavior just fine, or at least
>> better than the alternatives.

> Really?  I thought the issue was that no one had figured out how to do
> it, or that no one had written the patch, not that anyone thought the
> current behavior was particularly desirable.  What happens if you say
> ALTER TABLE .. DROP CONSTRAINT or COMMENT ON CONSTRAINT?  You just
> pick one at random?

No, because those syntaxes constrain the choice to one single
constraint.  Perhaps if the SQL committee had designed 'em,
there'd be an issue; but they are Postgres-isms.

			regards, tom lane