On Thu, 2010-03-18 at 17:17 -0400, Tom Lane wrote:
> > The VM cause wrong results if a bit is set that's not supposed to be --
> > right? Am I missing something? How does a seq scan skip visibility
> > checks and still produce right results, if it doesn't rely on the bit?
>
> It doesn't. The only thing we currently rely on the VM for is deciding
> whether a page needs vacuuming
Oh, my mistake. I misremembered the discussion and I thought the seq
scan optimization made it in.
> In order to do things like not visiting a page during scans, we'll have
> to solve the reliability issues.
Yeah, and also for the index-only scans.
Regards,Jeff Davis