Horton

Re: Effects of cascading references in foreign keys

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.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: 2006-08-22T03:50:02Z
Lists: pgsql-performance 
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.

Would someone please research this?  Thanks.

-- 
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

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