GeoNames Forum

Hello,

When browsing largest cities though the web interface, 10 largest cities in the rectangle are shown.

Could you please hint an algorithm for querying 10 "largest" items from a rectangle? Is this some kind of R-Tree modification?

Thanks.

The rectangle index is handled by the database. Just use a spatially enabled database like postgres.

Marc

Rectangle index is not a problem. It can be just an R-Tree (GiST) or, as you said, using spatial extentions (for example, PostGis for Postrges).

But rectangle index does not bring an effective solution for for querying 10 largest cities from a rectangle.

Obviously, something like

SELECT * FROM cities WHERE coordinates INSIDE (alt1, lng1, alt2, lng2) ORDER BY population LIMIT 10;

is far from optimal even if INSIDE relation is handled by spatial index.