From: Etsuro Fujita <etsuro.fujita@gmail.com>
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Nikolay Samokhvalov <nik@postgres.ai>
Cc: pgsql-hackers <pgsql-hackers@lists.postgresql.org>
Cc: ashutosh.bapat.oss@gmail.com
Subject: Re: [PG19][PATCH] Make postgres_fdw statistics import atomic
Date: Wed, 23 Sep 2026 19:21:03 +0900
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On Sat, Sep 19, 2026 at 7:55 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> > 2. Consider whether do_analyze_rel should do something (like clear the pg_statistic rows for the relation) in the case where numrows returned from the acquirefunc is zero.
>
> I also thought this option; it would make things logically clean, but
> I'm not sure we really need to do so, because in that case we set
> reltuples=0 in pg_class, which makes the planner effectively ignore
> the remaining attribute stats. See set_baserel_size_estimates(); if
> reltuples=0, we have rel->tuples=0, so whatever value
> clauselist_selectivity() calculates/returns based on the attribute
> stats, rel->rows (the estimated number of output tuples from the base
> relation) is set to zero.
Correction: since clamp_row_est() forces a row-count estimate to be at
least one row, we have rel->rows=1, not rel->rows=0. Sorry.
Best regards,
Etsuro Fujita
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Subject: Re: [PG19][PATCH] Make postgres_fdw statistics import atomic
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