Re: Teach pg_upgrade to deal with invalid databases

On Tue, Sep 22, 2026, at 1:25 PM, Nathan Bossart wrote:
> On Tue, Sep 22, 2026 at 09:10:44AM -0700, Bharath Rupireddy wrote:
>> Even if core drops them automatically, having pg_upgrade deal with
>> them is useful on its own IMHO, since the upgrade could start before
>> that happens. So, I prefer pg_upgrade skipping them without any
>> option, emitting info about the skipped ones, which will not happen
>> often in practice once core handles the drop.
>
> Yeah, I think we should do both. Automatic deletion is probably the best
> thing to do to handle leftover invalid databases, but as you say we can't
> rely on that happening before someone upgrades.
>

... or add a detailed error message to pg_upgrade saying that autovacuum or a
custom worker will remove the invalid databases in the next round. I don't like
the idea of having duplicate functionality. You might have to deal with a race
condition if pg_upgrade and autovacuum decide to act at the same time.

--
Euler Taveira
EDB https://www.enterprisedb.com/