Re: could not open relation with OID

Michael Paquier wrote on 1/26/22 9:14 PM:
> On Wed, Jan 26, 2022 at 05:30:01PM -0800, Ben Chobot wrote:
> Other things we've considered:
>>     - we run pg_repack, which certainly seems like it could make an error
>> like this, but we see this error in places and times that pg_repack isn't
>> currently running
> It could also take time for the issue to show up, depending on the
> state of the relcache.

So.... tell me more about stale relcaches? It turns out I was totally
wrong and this is being driven by pg_repack. I can even make it happen
pretty easily:

1. Put some data in a table with a single btree index on a primary db.
2. Set up streaming replication to a secondary db.
3. In a loop on the primary, have pg_repack repack the indices of that
table. (the -x flag)
4. In a loop on the secondary, have psql query the secondary db for an
indexed value of that table.

When I do this with replication, I can get the OID error consistently
within 30 minutes. Without replication, I've been unable to get it to
happen after 2 hours.

Given that this fails much faster on the secondary than the primary
(where it has yet to fail at all) I'm leaning towards a postgres bug,
but I'm happy to do more research to point the blame at something
pg_repack is doing, if you could point me at a thing to research.