Jeff Davis <pgsql@j-davis.com> writes:
> If I were to implement this idea, I think Heikki's bitmap of pages
> already read is the way to go.
I think that's a good way to guarantee that you'll not finish in time
for 8.3. Heikki's idea is just at the handwaving stage at this point,
and I'm not even convinced that it will offer any win. (Pages in
cache will be picked up by a seqscan already.)
regards, tom lane