Hi Ruud, > when I fetch the records, i only want those records which have a distance > *equal to or below the given distance*.
The usual technique in the geospatial world is to first select the points from the containing rectangle (bounding box, or BBOX), which is a much simpler calculation that helps discard most of the unwanted points. Then calculate the distance against the points inside that BBOX. Something like: SELECT * FROM table WHERE LAT >= :min_lat AND LAT <= :max_lat AND LON >= :min_lon AND LON <= :max_lon HAVING (distance_calculation) <= :radius The HAVING condition is only checked against the rows satisfying the WHERE conditions, so it's a good way to refine your selection with an expensive calculation. Obviously you'll want to index LAT and LON fields as well. Details on formulae for bbox and distance calculations: http://janmatuschek.de/LatitudeLongitudeBoundingCoordinates -- Oscar Fonts www.geomati.co <http://geomati.co> -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
