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? --------------------------------------------------------------------------- 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 > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073