Re: Bug? Concurrent COMMENT ON and DROP object

Excerpts from Robert Haas's message of mar jul 06 22:31:40 -0400 2010:
> On Tue, Jul 6, 2010 at 10:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Robert Haas <robertmhaas@gmail.com> writes:
> >> Obviously not.  We don't need to acquire an AccessExclusiveLock to
> >> comment on an object - just something that will CONFLICT WITH an
> >> AccessExclusiveLock.  So, use the same locking rules, perhaps, but
> >> take a much weaker lock, like AccessShareLock.
> >
> > Well, it probably needs to be a self-conflicting lock type, so that
> > two COMMENTs on the same object can't run concurrently.  But I agree
> > AccessExclusiveLock is too strong: that implies locking out read-only
> > examination of the object, which we don't want.
> 
> Hmm... so, maybe ShareUpdateExclusiveLock?

So COMMENT ON will conflict with (auto)vacuum?  Seems a bit weird ...