"Zeugswetter Andreas ADI SD" <Andreas.Zeugswetter@s-itsolutions.at> writes:
> ...This looks like a problem, since we might end up with a page filled with
> LP_DEAD slots, that all have no visibility info and can thus not be
> cleaned by vacuum.
No, it's the other way round: an LP_DEAD item pointer can *always* be
cleaned by VACUUM. It would not have become LP_DEAD unless someone had
confirmed that the pointed-to tuple was no longer visible to anyone.
The only reason we have LP_DEAD at all is that we don't want HOT pruning
to be required to remove the index entries that link to the item pointer.
regards, tom lane