Re: [PATCH] Doc: clarify that pg_upgrade statistics transfer works cross-version

On Tue, Mar 24, 2026 at 05:36:42AM -0700, Nikolay Samokhvalov wrote:
> On Mon, Mar 23, 2026 at 23:59 Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> wrote:
> ...
>
> I think that your patch offers too much detail,
> like from which relations the statistics are extracted.  Anybody
> who wants to know that level of detail probably has to read the
> source code anyway.
>
> How about adding a simple remark, like
>
> --- a/doc/src/sgml/ref/pgupgrade.sgml
> +++ b/doc/src/sgml/ref/pgupgrade.sgml
> @@ -837,6 +837,8 @@ psql --username=postgres --file=script.sql postgres
>       all statistics, such as those created explicitly with
>       <xref linkend="sql-createstatistics"/>, custom statistics added by
>       an extension, or statistics collected by the cumulative statistics
> system.
> +     Transferring optimizer statistics works regardless of the old
> cluster's
> +     major version.
>      </para>
>
>      <para>
>
>
> That would work too -- my goal was just to resolve confusion.

I was under the same impression --- that it only worked with upgrades
_from_ PG 18 and later. However, I can't find any documentation on this
limitation, so why did so many think this was true? I don't think
adding anything to the docs is the right approach.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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