From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Geoghegan <pg@bowt.ie>
cc: Klaudie Willis <Klaudie.Willis@protonmail.com>,
        PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: When Update balloons memory
In-reply-to: 
 <CAH2-Wzm8asKGAMy=bse5nTHq6CPZDdw5gHFH3WP8-Fdm25foQw@mail.gmail.com>
References: 
 <wJYzIcLjhFnsbCK8sy4lZZAojx7m04FwjsGF4WbrKj0gj2wLpaycQSEN1mtBUlhSAQGRvEdxZTwWRNV39UevSNWg8-h-tvWAL61pV4IuhW4=@protonmail.com>
 <3484560.1638889073@sss.pgh.pa.us>
 <YAjwxLJ1p4do7V4OkzpgwXrfV-fywioBsfvFaHnuY1Hbe-NjM0tsaCpJ_-KXwvFKF2YsQzQLCnFFFlMnyzd6TJ9UcXnQpcZfdZ1ZDcCqXIE=@protonmail.com>
 <189763.1639437451@sss.pgh.pa.us>
 <lviv_r7tA44gnx3rRU8VYdseWJLx-AzQCbsgdyz2-1Lse9ZmqDeLnzfDkBTut26kxlPZ8FX36TiKmCtXi5gAfhI-JVu-2n8fu7Dcta0Y3Ek=@protonmail.com>
 <261065.1639497535@sss.pgh.pa.us>
 <CAH2-Wzm54LA8EeOf6-cFZCHwigZ0YgQVgcmuyFr=b8w2pzQgzA@mail.gmail.com>
 <377324.1639510427@sss.pgh.pa.us>
 <CAH2-Wzm8asKGAMy=bse5nTHq6CPZDdw5gHFH3WP8-Fdm25foQw@mail.gmail.com>
Comments: In-reply-to Peter Geoghegan <pg@bowt.ie>
	message dated "Tue, 14 Dec 2021 15:17:16 -0800"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <562708.1639524532.1@sss.pgh.pa.us>
Date: Tue, 14 Dec 2021 18:28:52 -0500
Message-ID: <562709.1639524532@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/562709.1639524532%40sss.pgh.pa.us>
Precedence: bulk

Peter Geoghegan <pg@bowt.ie> writes:
> On Tue, Dec 14, 2021 at 11:33 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> And, not to be too picky, but does this cope with the case where
>> an indexed column is changed by a BEFORE trigger, not by the
>> query proper?

> No. It's much better to err in the direction of giving the hint,
> rather than not giving the hint. In order for us to make the category
> of error that seems like it might actually be a problem (not giving
> the hint when we should), the BEFORE trigger would have to "undo" an
> explicit change to an updated column.

Uh ... it seems that you are writing as though "giving the hint"
means saying that the column value changed.  That seems quite
confusingly backwards to me, as that is/ought to be the expected
assumption.  Maybe you should invert the flag state while you
are at it.

			regards, tom lane