To: Michael Fuhr <mike@fuhr.org>
Cc: Bruno Wolff III <bruno@wolff.to>, Martin Lesser <ml-pgsql@bettercom.de>,
	Stephan Szabo <sszabo@megazone.bigpanda.com>,
	pgsql-performance@postgresql.org
Subject: Re: Effects of cascading references in foreign keys 
In-reply-to: <11904.1130608918@sss.pgh.pa.us> 
References: <87acgszihk.fsf@nb-aspire.bettercom.de>
	<20051029142432.GA79557@winnie.fuhr.org>
	<20051029144947.GB21068@wolff.to>
	<20051029160527.GA80135@winnie.fuhr.org>
	<11904.1130608918@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Sat, 29 Oct 2005 14:01:58 -0400"
Date: Sat, 29 Oct 2005 14:35:25 -0400
Message-ID: <12097.1130610925@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

I wrote:
> Looking at this, I wonder if there isn't a bug or at least an
> inefficiency in 8.1.  The KeysEqual short circuit tests are still there
> in ri_triggers.c; aren't they now redundant with the test in triggers.c?
> And don't they need to account for the special case mentioned in the
> comment in triggers.c, that the RI check must still be done if we are
> looking at a row updated by the same transaction that created it?

OK, I take back the possible-bug comment: the special case only applies
to the FK-side triggers, which is to say RI_FKey_check, and that routine
doesn't attempt to skip the check on equal old/new keys.  I'm still
wondering though if the KeysEqual tests in the other RI triggers aren't
now a waste of cycles.

			regards, tom lane