Re: Effects of cascading references in foreign keys

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Michael Fuhr <mike(at)fuhr(dot)org>, Bruno Wolff III <bruno(at)wolff(dot)to>, Martin Lesser <ml-pgsql(at)bettercom(dot)de>, Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Effects of cascading references in foreign keys
Date: 2005-12-07 04:41:16
Message-ID: 200512070441.jB74fGY21078@candle.pha.pa.us
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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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