"D'Arcy J.M. Cain" <darcy@druid.net> writes:
> Also odd, why would running over NFS have any bearing on it if we 
> could find such a place?

Yup, 'tis the question.  The only theory I have been able to come up
with is that there's something flaky about your network hardware,
such that Postgres sometimes reads bad data from the NFS server.
But the glaring problem with that theory is that bad data coming
from a regular disk drive generally results in error messages or
core dumps.  Silent hangs would be a new behavior AFAIR.

At this point I think you need to rebuild with --enable-debug and
--enable-cassert (if you didn't already) and then capture some
stack traces from the stuck backend.  We have to find out what the
backend thinks it's doing.

BTW: *are* we certain it's associated with NFS, and not a hardware
problem on your NetBSD box?  Can you perform the same tests running
the database off a local disk?

			regards, tom lane