Re: Effects of cascading references in foreign keys

Bruce Momjian <pgman@candle.pha.pa.us>

From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
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
Date: 2005-12-07T04:41:16Z
Lists: pgsql-performance
Would someone add a comment in the code about this, or research it?

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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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