Re: [HACKERS] PostgreSQL for VAX on NetBSD/OpenBSD

[Tom Lane <tgl%sss.pgh.pa.us@localhost>]

Greg Stark <stark%mit.edu@localhost> writes:
> So I've been playing with this a bit. I have simh running on my home
> server as a Vax  3900 with NetBSD 6.1.5. My home server was mainly
> intended to be a SAN and its cpu is woefully underpowered so the
> resulting VAX is actually very very slow. So slow I wonder if there's
> a bug in the emulator but anyways.

Fun fun!

> There are some planner tests that fail with floating point exceptions
> -- that's probably a bug on our part. And I've seen at least one
> server crash (maybe two) apparently caused by one as well which I
> don't believe is expected.

That seems worth poking into.

> 3) The tests take so long to run that autovacuum kicks in and the
> tests start producing rows in inconsistent orderings. I assume that's
> a problem we've run into on the CLOBBER_CACHE animals as well?

I'd tentatively bet that it's more like planner behavioral differences
due to different floating-point roundoff.

> 4) One of the tablesample tests seems to freeze indefinitely. I
> haven't looked into why yet. That might indeed indicate that the
> spinlock code isn't working?

The tablesample tests seem like a not-very-likely first place for such a
thing to manifest.  What I'm thinking is that there are places in there
where we loop till we get an expected result.  Offhand I thought they were
all integer math; but if one was float and the VAX code wasn't doing what
was expected, maybe we could blame this on float discrepancies as well.

			regards, tom lane