"Stephen Samuel (Sam)" <sam@sksamuel.com> writes:
> This index covers both columns needed in the predicate/projection, and the
> visibility bit is almost always set, why does it need to go to the heap at
> all and doesn't just get what it needs from the index?
Peter's theory was that the particular tuples you were fetching were
in not-all-visible pages. That seems plausible to me.
regards, tom lane