+-- Compute a base address rank from the extent of the given geometry.
+--
+-- This is all simple guess work. We don't need particularly good estimates
+-- here. This just avoids to have very high ranked address parts in features
+-- that span very large areas (or vice versa).
+CREATE OR REPLACE FUNCTION geometry_to_rank(search_rank SMALLINT, geometry GEOMETRY, country_code TEXT)
+ RETURNS SMALLINT
+ AS $$
+DECLARE
+ area FLOAT;
+BEGIN
+ IF ST_GeometryType(geometry) in ('ST_Polygon','ST_MultiPolygon') THEN
+ area := ST_Area(geometry);
+ ELSIF ST_GeometryType(geometry) in ('ST_LineString','ST_MultiLineString') THEN
+ area := (ST_Length(geometry)^2) * 0.1;
+ ELSE
+ RETURN search_rank;
+ END IF;
+
+ -- adjust for the fact that countries come in different sizes
+ IF country_code IN ('ca', 'au', 'ru') THEN
+ area := area / 5;
+ ELSIF country_code IN ('br', 'kz', 'cn', 'us', 'ne', 'gb', 'za', 'sa', 'id', 'eh', 'ml', 'tm') THEN
+ area := area / 3;
+ ELSIF country_code IN ('bo', 'ar', 'sd', 'mn', 'in', 'et', 'cd', 'mz', 'ly', 'cl', 'zm') THEN
+ area := area / 2;
+ END IF;
+
+ IF area > 1 THEN
+ RETURN 7;
+ ELSIF area > 0.1 THEN
+ RETURN 9;
+ ELSIF area > 0.01 THEN
+ RETURN 13;
+ ELSIF area > 0.001 THEN
+ RETURN 17;
+ ELSIF area > 0.0001 THEN
+ RETURN 19;
+ ELSIF area > 0.000005 THEN
+ RETURN 21;
+ END IF;
+
+ RETURN 23;
+END;
+$$
+LANGUAGE plpgsql IMMUTABLE;
+