> One more direction could be implementing "MCV" for range of values (group
> values and interpolate in between). Consider statistics on timestamp column
> that says that for "2008-December" there are as many X rows, for
> "2008-November" as many as Y, etc. That could be used for rather accurate
> cardinality estimation of "between" cases, while keeping number of entries
> in "MCV" list small.
>
I suggested this earlier (
http://archives.postgresql.org/pgsql-hackers/2008-06/msg00353.php ).
If there's interest, I'd be happy to clean up my patch and submit it
for 8.5
-Nathan