Re: Teach pg_upgrade to deal with invalid databases

Hi,

On 2026-09-21 14:01:09 -0500, Nathan Bossart 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.

I kinda wonder if the better answer would be to teach autovac or such to drop
such databases.

I don't love pg_upgrade ignoring invalid databases, but I can't actually come
up with a convincing reason for it, so ...

Greetings,

Andres Freund