geometry op class for index only scans (PostgreSQL 9.2+)

[robe]

PostgreSQL 9.2 now supports index only scans. Originally I thought we couldn't take advantage of it, but I suspect it might help with quick && count checks.

See this thread.

 http://archives.postgresql.org/pgsql-hackers/2012-01/msg00414.php sadly this won't help much with the more useful use case of

ST_Intersects(... ) as that still needs to pull the geometry though I guess it would only need in the case of if index check passes so might still be very useful. Dunno.