Hello, I am working on spatial indexing for Derby using Healpix: http://healpix.jpl.nasa.gov/.
It is way to split sphere into pixels and number them. Pixel numbers are associative (near locations have near numerical values). And can be stored in long column with btree index. Pixel resolution can be choosed, maximum is 0.2 arcsec. Healpix was originally developed for astronomy. My program is also astronomical application. But it works for geographical coordinates as well. Currently I implemented spatial indexing using 1:N table. But on high resolutions it generates too much rows (one for each pixel). So next step is range set, to reduce number of rows. Related code is relatively simple and compact. If someone wants help, it would be very welcomed. Jan Kotek http://kotek.net/opencoeli.
