Re: regarding statistics retaining with 18 Upgrade

Robert Treat <rob@xzilla.net>

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From: Robert Treat <rob@xzilla.net>

To: Bruce Momjian <bruce@momjian.us>

Cc: Rambabu V <ram.wissen@gmail.com>, pgsql-hackers@postgresql.org

Date: 2025-11-15T23:52:15Z

Lists: pgsql-hackers

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v1-0001-Clarify-statistics-dumped-by-statistics.patch (application/octet-stream)

On Sat, Nov 15, 2025 at 9:32 AM Bruce Momjian <bruce@momjian.us> wrote:
> On Sat, Nov 15, 2025 at 06:02:53PM +0800, Rambabu V wrote:
> > Hi Team,
> >
> > seems stats are not retained after upgrade. Below are the artifacts , is it
> > expected? as per the release notes statistics should be retained.
>
> Uh, it is the _optimizer_ statistics that are preserved by pg_upgrade,
> not the cumulative statistics system:
>
>         https://www.postgresql.org/docs/current/monitoring-stats.html
>
> Yes, they are easily confused.
>

I wonder if it might be worth trying to clarify this a little bit
more... perhaps something like the attached?

Robert Treat
https://xzilla.net