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To: Joe Conway <mail@joeconway.com>
cc: "Hackers (PostgreSQL)" <pgsql-hackers@postgresql.org>
Subject: Re: Values list-of-targetlists patch for comments (was Re: [PATCHES]
	8.2 features?)
In-reply-to: <44CFBC78.2020508@joeconway.com> 
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Comments: In-reply-to Joe Conway <mail@joeconway.com>
	message dated "Tue, 01 Aug 2006 13:41:28 -0700"
Date: Tue, 01 Aug 2006 22:52:00 -0400
Message-ID: <28624.1154487120@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Joe Conway <mail@joeconway.com> writes:
> Tom Lane wrote:
>> What I'm inclined to do for 8.2 is to disallow OLD/NEW references in
>> multi-element VALUES clauses; the feature is still tremendously useful
>> without that.

> Given the timing, this sounds like a reasonable approach. I agree that 
> the feature has lots of interesting uses -- I'd hate to see us lose 
> that. Disallowing OLD/NEW references doesn't contradict the spec in any 
> way AFAIK either.

I don't think rules are in the spec at all ;-) ... so no, that's not
a problem.  My example demonstrated a pretty likely use:

create rule r2 as on update to src do
	insert into log values(old.*, 'old'), (new.*, 'new');

but for the moment we can tell people to work around it the way
they always have:

create rule r2 as on update to src do
	insert into log select old.*, 'old' union all new.*, 'new';

or just use two separate INSERT commands in the rule.

We oughta fix it later, but I don't feel ashamed to have a restriction
like this in the first cut.

			regards, tom lane