Re: Teach pg_upgrade to deal with invalid databases

On Mon, Sep 21, 2026 at 3:01 PM Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
>
> On Tue, Sep 08, 2026 at 10:11:23AM -0700, Bharath Rupireddy wrote:
> > pg_upgrade skipping the invalid databases seems like the right
> > approach. Whether or not this has to be put behind an option and
> > retain the current error behavior is something we need to agree on. I
> > still think pg_upgrade can just skip and the error could be removed,
> > unless anyone thinks otherwise.
>
> I think we ought to simply skip the invalid databases without any sort of
> option. The only counterargument I'm aware of is that someone might want
> to try recoving the database, but AFAIK there's no supported recovery
> mechanism. Even if there was, it seems pretty unlikely that a user would
> cancel an errant DROP DATABASE and then proceed to run pg_upgrade before
> attempting recovery. Furthermore, I believe the proposed skipping behavior
> more closely matches the previous behavior before we started using
> datconnlimit == -2 to mean the database is invalid.
>

+1 from me; If people are really concerned, I think it'd be enough to
just be a little more chatty about it in the logs; ie. add some
warnings and/or notes when we find/skip an invalid database to the
various logs and instructions during the upgrade process.

Robert Treat
https://xzilla.net