Bruce Momjian <bruce@momjian.us> writes:
> I thought some more about this and I don't want autovacuum to run on the
> old server. This is because pg_dumpall --binary-upgrade --schema-only
> grabs the datfrozenxid for all the databases at the start, then connects
> to each database to gets the relfrozenxids. I don't want to risk any
> advancement of either of those during the pg_dumpall run.
Why? It doesn't really matter --- if you grab a value that is older
than the latest, it's still valid. As Robert said, you're
over-engineering this, and thereby introducing potential failure modes,
for no gain.
regards, tom lane