Re: pg15b2: large objects lost on upgrade

On Thu, Aug 4, 2022 at 1:49 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Note that the patch you proposed at [1] will not fix anything.
> It turns off autovac in the new node, but the buildfarm failures
> we've seen appear to be due to autovac running on the old node.
> (I believe that autovac in the new node is *also* a hazard, but
> it seems to be a lot less of one, presumably because of timing
> considerations.) To make it work, we'd have to shut off autovac
> in the old node before starting pg_upgrade,

Yeah, that's a fair point.

> and that would make it
> unacceptably (IMHO) different from what real users will do.

I don't agree with that, but as you say, it is a matter of opinion. In
any case, what exactly do you want to do now?

Jonathon Katz has proposed a patch to do the fuzzy comparison which I
believe to be incorrect because I think it compares, at most, the
horizons for one table in the database.

I could go work on a better version of that, or he could, or you
could, but it seems like we're running out of time awfully quick here,
given that you wanted to have this resolved today and it's almost the
end of today.

I think the most practical alternative is to put this file back to the
way it was before I started tinkering with it, and revisit this issue
after the release. If you want to do something else, that's fine, but
I'm not going to be available to work on this issue over the weekend,
so if you want to do something else, you or someone else is going to
have to take responsibility for whatever further stabilization that
other approach may require between now and the release.

--
Robert Haas
EDB: http://www.enterprisedb.com