Re: [PATCH] pageinspect function to decode infomasks

On Tue, Aug 15, 2017 at 10:54 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> Or at least make the filtering optional.
>
> I don't think "filtering" is the right way to think about it.  It's
> just labeling each combination of bits with the meaning appropriate to
> that combination of bits.

I do. -1 to not just showing what's on the page -- if the
HEAP_XMIN_COMMITTED and HEAP_XMIN_ABORTED bits are set, then I think
we should show them. Yeah, I accept that there is a real danger of
confusing people with that. Unfortunately, I think that displaying
HEAP_XMIN_FROZEN will cause even more confusion. I don't think that
HEAP_XMIN_FROZEN is an abstraction at all. It's a notational
convenience.

I don't think it's our place to "interpret" the bits. Are we *also*
going to show HEAP_XMIN_FROZEN when xmin is physically set to
FrozenTransactionId? Where does it end?

I think that we should prominently document that HEAP_XMIN_COMMITTED
|HEAP_XMIN_ABORTED == HEAP_XMIN_FROZEN, rather than trying to hide
complexity that we have no business hiding in a tool like pageinspect.

-- 
Peter Geoghegan