At the very least that note about this behavior should be highlighted, probably on the Trigger Behavior page and not buried in a bunch of notes on the Create Trigger page.
On Fri, Sep 13, 2019 at 4:03 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Judy Loomis <hoodie.j...@gmail.com> writes: > > I'm going to have to really look at all my BEFORE UPDATE triggers and > make > > sure we're not missing any more. > > And I have to stop telling management that a trigger means we always know > > when a value changes. > > Well, you can rely on that, just not like this. Use an AFTER trigger > (else, you can't be sure it fires after all the BEFORE triggers) > and instead of triggering it with a column parameter, have it do > something like "if old.col is distinct from new.col". > > Yeah, it's a bit slower that way, but there's no free lunch, > especially if you don't trust your other triggers. (Although, > if you have so many triggers that that's a problem, I think you > might have some other design issues.) > > regards, tom lane > -- ---------------------------------------------------------- *Judy Loomis* 469.235.5839
