Re: [PG19][PATCH] Make postgres_fdw statistics import atomic

On Sat, Sep 19, 2026 at 7:55 PM Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)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