Re: Import Statistics in postgres_fdw before resorting to sampling.

From: Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com>
To: Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, jkatz(at)postgresql(dot)org, nathandbossart(at)gmail(dot)com
Subject: Re: Import Statistics in postgres_fdw before resorting to sampling.
Date: 2025-12-15 10:01:44
Message-ID: CAPmGK172HWnpw+RZ4ZN7dmUAUGH1-9sg-bX981LTVZQ7F+F2bg@mail.gmail.com
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On Mon, Dec 15, 2025 at 5:01 AM Corey Huinker <corey(dot)huinker(at)gmail(dot)com> wrote:

>> Ah, I mean the case where the foreign table is an inheritance parent
>> on the *local* side. In that case, the return would cause us to skip
>> the recursive ANALYZE (i.e., do_analyze_rel() with inh=true), leading
>> to no inherited stats. I agree that the case is minor, but I don't
>> think that that's acceptable.

> When such a corner case occurs (stats import configured to true, but table is an inheritance parent), should we raise an error, or raise a warning and return false on the CanImportStats() call? I guess the answer may depend on the feedback we get.

As mentioned upthread, the FDW API that I proposed addresses this
issue; even in such a case it allows the FDW to import stats, instead
of doing the normal non-recursive ANALYZE, and then do the recursive
ANALYZE, for the inherited stats.

Best regards,
Etsuro Fujita

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