Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> That's a killer reason, I suppose. I was really trying to uncover what
> the thinking was, so we can document it. Having VACUUM ignore it
> completely seems wrong.
What you seem to be forgetting is that VACUUM is charged with cleaning
out LP_DEAD tuples, which HOT cannot do. And the page header fields are
set (quite properly so) with HOT's interests in mind not VACUUM's.
regards, tom lane