Date: Mon, 09 Jun 2008 12:37:47 -0400
From: Robert Treat <xzilla@users.sourceforge.net>
Subject: Re: pg_dump restore time and Foreign Keys
In-reply-to: <20406.1213027167@sss.pgh.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Simon Riggs <simon@2ndquadrant.com>, Decibel! <decibel@decibel.org>,
	Andrew Dunstan <andrew@dunslane.net>, pgsql-hackers@postgresql.org
Message-id: <200806091237.49153.xzilla@users.sourceforge.net>
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On Monday 09 June 2008 11:59:27 Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > On Mon, 2008-06-09 at 11:33 -0400, Tom Lane wrote:
> >> No, we are running a large query to which the user *thinks* he knows the
> >> answer.  There are any number of reasons why he might be wrong.
> >
> > Of course. I should have said "to which we already know the answer" to
> > indicate I'm passing on others' criticisms of us.
>
> [ shrug... ]  We don't know the answer either, and anyone who says
> we do is merely betraying his ignorance of the number of ways to load
> a foot-gun.
>

I think the more realistic scenario (based on the FK idea) is that you want to 
prevent any future rows from coming without validating the FK, and you're 
willing to clean up any violators after the fact, since you can make that 
an "out of the critical path" operation.

if you extend this to a more general "create constraint concurrently" (to 
handle normal constraint, not null constraints, etc...), it would certainly 
be a big win, and i think most would see it as a reasonable compromise. 

-- 
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL