>> As Heikki says, maybe this wouldn't be an issue at all if we can do it
>> during ANALYZE instead, but I don't know if that works.
>
> I'm not convinced you can get a sufficiently good estimate from a small
> subset of pages.
Note that if this requires VACUUM rather than ANALYZE, it introduces a
problem for data warehousing users, who can go years between vacuums of
their largest tables.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com