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From: Corey Huinker <corey.huinker@gmail.com>
Date: Sat, 20 Dec 2025 11:07:11 -0500
Message-ID: 
 <CADkLM=e_fWhLdwE=HnExSCO6bY2WVpaUMbQRSBN2nw6fh78qUg@mail.gmail.com>
Subject: Re: SQL-level pg_datum_image_equal
To: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Wed, Dec 10, 2025 at 12:46=E2=80=AFPM Matthias van de Meent <
boekewurm+postgres@gmail.com> wrote:

> Hi,
>
> One of our customers has this workload where every so often they
> update the whole table to make sure it's up-to-date. In general, you'd
> probably want to use MERGE for such a workload and ignore all rows
> that already have only matching data, but there's a catch: PostgreSQL
> doesn't have an efficient way to check if the provided data is
> actually equal in all senses of the word, so we can't easily and
> cheaply determine whether an update is needed; which is one reason why
> the full table was updated every time.
>

Have you ruled out the suppress_redundant_updates_trigger?

https://www.postgresql.org/docs/current/functions-trigger.html

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<div dir=3D"ltr"><div class=3D"gmail_quote gmail_quote_container"><div dir=
=3D"ltr" class=3D"gmail_attr">On Wed, Dec 10, 2025 at 12:46=E2=80=AFPM Matt=
hias van de Meent &lt;<a href=3D"mailto:boekewurm%2Bpostgres@gmail.com">boe=
kewurm+postgres@gmail.com</a>&gt; wrote:<br></div><blockquote class=3D"gmai=
l_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,20=
4,204);padding-left:1ex">Hi,<br>
<br>
One of our customers has this workload where every so often they<br>
update the whole table to make sure it&#39;s up-to-date. In general, you=
9;d<br>
probably want to use MERGE for such a workload and ignore all rows<br>
that already have only matching data, but there&#39;s a catch: PostgreSQL<b=
r>
doesn&#39;t have an efficient way to check if the provided data is<br>
actually equal in all senses of the word, so we can&#39;t easily and<br>
cheaply determine whether an update is needed; which is one reason why<br>
the full table was updated every time.<br></blockquote><div><br></div><div>=
Have you ruled out the=C2=A0suppress_redundant_updates_trigger?</div><div><=
br></div><div><a href=3D"https://www.postgresql.org/docs/current/functions-=
trigger.html">https://www.postgresql.org/docs/current/functions-trigger.htm=
l</a></div></div></div>

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