> > One more question I have though is:
> > How do you make sure noone (e.g. autovacuum analyze)
> > unfreezes tuples after the vacuum freeze ?
>
> I will start a new thread to answer this question, but the short answer
> is that the freeze only needs to happen in a fresh initdb database, and
> once clog is copied over, new transactions can be created normally.
Yes.
I am still answering here because my question was related to upgrade.
I think you need to turn off autovacuum before freezing to avoid a later analyze
that unfreezes pg_class (or the stats table).
Also to really have all tables frozen I think the order of the freezes is crutial.
Consider the order:
freeze pg_class
freeze pg_columns --> won't this unfreeze pg_class ?
And what about shared catalogs ?
Or does heap_update not change the xid ? Or can it use a frozen xid ?
Or does it all work when done in one large transaction ?
I think I am confused, sorry :-(
Andreas
