"Daniel Farina" <daniel(at)heroku(dot)com> writes:
> We have on hand a database that makes heavy use of the txid_snapshot family
> of functions, and recently it just passed its 4^32 transaction mark.
> Unfortunately, upon wraparound the xid epoch appears to not have been
> incremented, remaining at 0.
I failed to reproduce this here, and a look at the code responsible for
xid epoch maintenance reveals no obvious way that it could have been
bypassed. So there's some fairly critical piece of context that you're
not telling us ...
regards, tom lane