On Tue, Jul 6, 2021 at 3:49 PM Bruce Momjian <br...@momjian.us> wrote: > My point is that there are a lot internals involved here that are not > part of pg_upgrade, though it probably only affects pg_upgrade. Anyway, > Bertrand patch seems to have what I need.
I was confused by your remarks because I am kind of looking at it from the opposite angle. At least now that I've thought about it a bit. Since the snippet of pg_resetwal code that sets oldestXid wasn't ever intended to be used by pg_upgrade, but was anyway, what we have is a something that's clearly totally wrong (at least in the pg_upgrade case). It's not just wrong for pg_upgrade to do things that way -- it's also wildly unreasonable. We heard a complaint about this from Reddit only because it worked "as designed", and so made the cluster immediately have an anti-wraparound autovacuum. But why would anybody want that behavior, even if it was implemented correctly? It simply makes no sense. The consequences of this bug are indeed complicated and subtle and will probably never be fully understood. But at the same time fixing the bug now seems kind of simple. (Working backwards to arrive here was a bit tricky, mind you.) -- Peter Geoghegan
