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.albe@cybertec.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@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Do not let urgent matters crowd out time for investment in the future.