Re: pg15b2: large objects lost on upgrade

On Sat, Jul 02, 2022 at 08:34:04AM -0400, Robert Haas wrote:
> On Fri, Jul 1, 2022 at 7:14 PM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> > I noticed this during beta1, but dismissed the issue when it wasn't easily
> > reproducible. Now, I saw the same problem while upgrading from beta1 to beta2,
> > so couldn't dismiss it. It turns out that LOs are lost if VACUUM FULL was run.
>
> Yikes. That's really bad, and I have no idea what might be causing it,
> either. I'll plan to investigate this on Tuesday unless someone gets
> to it before then.

As far as I can see the data is still there, it's just that the new cluster
keeps its default relfilenode instead of preserving the old cluster's value:

regression=# table pg_largeobject;
loid | pageno | data
------+--------+------
(0 rows)

regression=# select oid, relfilenode from pg_class where relname = 'pg_largeobject';
oid | relfilenode
------+-------------
2613 | 2613
(1 row)

-- using the value from the old cluster
regression=# update pg_class set relfilenode = 39909 where oid = 2613;
UPDATE 1

regression=# table pg_largeobject;
loid | pageno |
-------+--------+-----------------
33211 | 0 | \x0a4920776[...]
34356 | 0 | \xdeadbeef
(2 rows)