Chris Browne <cbbrowne@acm.org> writes:
> Ron's comment is well-suggested[1], but a bit of a red herring, as the
> column will *NEVER* be "physically dropped." [2]
Check.
> What will happen is that new tuples will not have the column, but old
> tuples will continue to have the (invisible) column for as long as
> they "live" in the database.
Actually, new tuples still have the column, it's just always NULL
(and hence takes no space except for a bit in the nulls-bitmap).
regards, tom lane