Re: postgres_fdw vs. force_parallel_mode on ppc

Robert Haas <robertmhaas@gmail.com> writes:
> Sure.  If you have an idea what the right thing to do is, please go
> ahead.

Yeah, I'll modify the patch and commit sometime later today.

> I actually don't have a clear idea what's going on here.  I
> guess it's that the wait_for_stats() guarantees that the stats message
> from the index insertion has been received but the status messages
> from the "trunc" tables might not have gotten there yet.

That's what it looks like to me.  I now think that the apparent
connection to parallel query is a mirage.  The reason we've only
seen a few cases so far is that the flapping test is new: it
wad added in commit d42358efb16cc811, on 20 Feb.  If we left it
as-is, I think we'd eventually see the same failure without forcing
parallel mode.  In fact, that's pretty much what you describe below,
isn't it?  The pg_sleep is sort of half-bakedly substituting for
a proper wait.
        regards, tom lane