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Re: Effects of cascading references in foreign keys

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Michael Fuhr <mike(at)fuhr(dot)org>
Cc: 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: 2005-10-29 18:35:25
Message-ID: 12097.1130610925@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
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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Subject: Re: Effects of cascading references in foreign keys
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