Date: Fri, 1 May 2015 16:24:03 +0200
From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Peter Geoghegan <pg@heroku.com>, hlinnaka <hlinnaka@iki.fi>,
 Jeff Janes <jeff.janes@gmail.com>, Stephen Frost <sfrost@snowman.net>,
 Dean Rasheed <dean.a.rasheed@gmail.com>, Bruce Momjian <bruce@momjian.us>,
 Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: INSERT ... ON CONFLICT UPDATE/IGNORE 4.0
Message-ID: <20150501142403.GG22649@awork2.anarazel.de>
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On 2015-05-01 10:21:27 -0400, Robert Haas wrote:
> On Fri, May 1, 2015 at 10:10 AM, Andres Freund <andres@anarazel.de> wrote:
> > On 2015-05-01 10:06:42 -0400, Robert Haas wrote:
> >> On Fri, May 1, 2015 at 9:58 AM, Andres Freund <andres@anarazel.de> wrote:
> >> > would you rather have EXCLUDED.data refer to the tuple version from
> >> > VALUES (or a SELECT or ...) or to version from the BEFORE trigger?
> >>
> >> I think it would be completely shocking if it didn't refer to the
> >> version returned by the BEFORE trigger.  My interpretation of the
> >> semantics of BEFORE triggers is that, once the trigger has fired and
> >> returned a new tuple, things should proceed just as if that new tuple
> >> were the one originally provided by the user.
> >
> > Well, it's a BEFORE INSERT trigger, not a BEFORE UPDATE, that's why I'm
> > not so sure that argument applies.
> 
> Would the BEFORE UPDATE trigger even fire in this case?

BEFORE UPDATE triggers fire for INSERT ... ON CONFLICT UPDATE iff
there's a conflict, yes.

> The thing is, suppose somebody puts a BEFORE INSERT trigger and a
> BEFORE UPDATE trigger on the table, and each of those triggers does
> this:
> 
> NEW.last_updated_time = clock_timestamp();
> return NEW;
> 
> That should work, and should cover all cases, even if you're using UPSERT.

The BEFORE UPDATE would catch things in this case.

Greetings,

Andres Freund


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