Greg Smith <gsmith@gregsmith.com> writes:
> ... To put that another way: if I've run a manual vacuum, is it true
> that it will have updated all the hint bits to XMIN_COMMITTED for all the
> tuples that were all done when the vacuum started?
Any examination whatsoever of a tuple --- whether by vacuum or any
ordinary DML operation --- will update its hint bits to match the
commit/abort status of the inserting/deleting transaction(s) as of
the instant of the examination. Your statement above is true but
is weaker than reality.
regards, tom lane