Bruce Momjian <pgman@candle.pha.pa.us> writes:
> I don't feel too bad about the runtime cost if only subtransactions are
> paying that cost.
That's exactly why I'm so exercised about what's been done to the
HeapTupleSet/Get macros. That's significant cost that's paid even when
you're not using *any* of this stuff.
> I know we are really stretching the system here but I
> would like to try a little more rather than give up and taking a space
> hit for all tuples.
I don't even have any confidence that there are no fundamental bugs
in the phantom-xid concept :-(. I'd be willing to play along if an
implementation that seemed acceptable speedwise were being offered,
but this thing is not preferable to four-more-bytes even if it works.
regards, tom lane