Re: VACUUM (DISABLE_PAGE_SKIPPING on)

The docs are misleading for this feature, since they say:
"This option disables all page-skipping behavior, and is
intended to be used only when the contents of the visibility map are
suspect, which should happen only if there is a hardware or software
issue causing database corruption."

The code is quite clear: DISABLE_PAGE_SKIPPING makes the vacuum into
an aggressive vacuum. Line 487, heap_vacuum_rel().  Aggressive vacuums
can still skip a page that is frozen, and rely on the visibility map
for that information.

So the docs are wrong - we don't disable *all* page-skipping and it is
not appropriate to warn users away from this feature by saying "is
intended to be used only when the contents of the visibility map are
suspect".