Re: pg15b2: large objects lost on upgrade

On Mon, Jul 18, 2022 at 02:57:40PM -0400, Robert Haas wrote:
> So I tried implementing this but I didn't get it quite right the first
> time. It's not enough to call smgrdounlinkall() instead of
> RelationDropStorage(), because just as RelationDropStorage() does not
> actually drop the storage but only schedules it to be dropped later,
> so also smgrdounlinkall() does not in fact unlink all, but only some.
> It leaves the first segment of the main relation fork around to guard
> against the hazards discussed in the header comments for mdunlink().
> But those hazards don't really matter here either, because, again, any
> failure will necessarily require that the entire new cluster be
> destroyed, and also because there shouldn't be any concurrent activity
> in the new cluster while pg_upgrade is running. So I adjusted
> smgrdounlinkall() to actually remove everything when IsBinaryUpgrade =
> true. And then it all seems to work: pg_upgrade of a cluster that has
> had a rewrite of pg_largeobject works, and pg_upgrade of a cluster
> that has not had such a rewrite works too. Wa-hoo.

Using the IsBinaryUpgrade flag makes sense to me.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson