From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200512070441.jB74fGY21078@candle.pha.pa.us>
Subject: Re: Effects of cascading references in foreign keys
In-Reply-To: <12097.1130610925@sss.pgh.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 6 Dec 2005 23:41:16 -0500 (EST)
CC: Michael Fuhr <mike@fuhr.org>, Bruno Wolff III <bruno@wolff.to>,
	Martin Lesser <ml-pgsql@bettercom.de>,
	Stephan Szabo <sszabo@megazone.bigpanda.com>,
	pgsql-performance@postgresql.org
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Would someone add a comment in the code about this, or research it?

---------------------------------------------------------------------------

Tom Lane wrote:
> 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
> 
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