From: Tom Lane <tgl@sss.pgh.pa.us>
To: Laurenz Albe <laurenz.albe@cybertec.at>
cc: Durgamahesh Manne <maheshpostgres9@gmail.com>,
        pgsql-general <pgsql-general@lists.postgresql.org>
Subject: Re: Regarding query optimisation (select for update)
In-reply-to: <826536fd65cb6b25e996ac449336ce9c2476174b.camel@cybertec.at>
References: <CAJCZko+fiU+=NSEGY7d7YMpFxg_jANpiO-LU6ur+yqRc_Ej6eQ@mail.gmail.com> <c116cd0011bb36a55f58274daecf4464a23911e7.camel@cybertec.at> <CAJCZkoLJ6G9J3iK591o35UaKu3x7Kn96ma-u_yqGNgkrLjf6ag@mail.gmail.com> <826536fd65cb6b25e996ac449336ce9c2476174b.camel@cybertec.at>
Comments: In-reply-to Laurenz Albe <laurenz.albe@cybertec.at>
	message dated "Tue, 15 Jul 2025 16:06:20 +0200"
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Date: Tue, 15 Jul 2025 10:45:44 -0400
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Laurenz Albe <laurenz.albe@cybertec.at> writes:
> Text is easier to read than images...

Indeed.

> Anyway, this statement was done in under a millisecond.
> I wouldn't call that slow...

It looks to me like this EXPLAIN ANALYZE was done against a totally
empty table, so probably in a freshly-set-up dev environment.  That
is not going to be helpful in identifying your production problem.
Note the caveat at [1]:

    EXPLAIN results should not be extrapolated to situations much
    different from the one you are actually testing; for example,
    results on a toy-sized table cannot be assumed to apply to large
    tables.

			regards, tom lane

[1] https://www.postgresql.org/docs/current/using-explain.html#USING-EXPLA=
IN-CAVEATS