Greg Stark <gsstark@mit.edu> writes:
> The last tuple is marked strangely I think. I don't think it's
> supposed to have XMAX_INVALID if xmax is 0 but I could be wrong. Also,
> I don't understand why it's marked as UPDATED if ctid and xmax aren't
> set.
No, that all looks right to me. UPDATE sets HEAP_UPDATED on the newer
version of the row, not the older one. What looks interesting to me is
that the last update isn't marked HEAP_ONLY_TUPLE, ie, it's not in the
same HOT chain. Why is that I wonder ...
> I'm wondering if the page allvisible flag is set. The visibility map
> is one of the few 8.4 patches which impact transaction visibility.
But we don't use that while examining individual tuples, do we?
regards, tom lane