--- android/TrainInfoService/src/dk/thoerup/traininfoservice/StationDAO.java	2010/05/18 17:56:43	733
+++ android/TrainInfoService/src/dk/thoerup/traininfoservice/StationDAO.java	2010/05/19 12:56:10	741
@@ -101,15 +101,21 @@
 		return result;
 	}
 	 
+	//the "hack" with max 1.5 degrees latitude and 2.5 degrees longitude is only valid since we only service danish trains
+	// in denmark 1.5dg latitude ~ 165km, 2.5dg longitude ~ 155km
+	
+	// the ultra fast method  (and only slightly inaccurate as long as we only cover a limited geographically area)
+	// is using an aproximation of the length of 1 latitude degree and 1 longitude degree and just use pythagoras to 
+	// calculate the distance:
+    //     sqrt( power(abs(latitude-?)*111320, 2) + power(abs(longitude-?)*63000,2) )::int as calcdist 
+	
 	public List<StationBean> getByLocation(double latitude, double longitude) throws SQLException {
-		String SQL = "SELECT * FROM ( "+
-		"               SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address," + 
-		"                     earth_distance( earth_coord, ll_to_earth(?,?))::int AS calcdist " + 
-		"               FROM trainstations " +
-		"               WHERE enabled = true " +
-		"       ) AS trainstations2 " +
-		"ORDER BY calcdist ASC " + 
-		"LIMIT 4 ";
+		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address," + 
+					 "       earth_distance( earth_coord, ll_to_earth(?,?))::int AS calcdist " + 
+					 "FROM trainstations " +
+					 "WHERE enabled = true AND abs(latitude-?)<1.5 AND abs(longitude-?)<2.5 " +
+					 "ORDER BY calcdist ASC " + 
+					 "LIMIT 4 ";
 		List<StationBean> result;
 		Connection conn = null;
 		PreparedStatement stmt = null;
@@ -119,6 +125,8 @@
 			stmt = conn.prepareStatement(SQL);
 			stmt.setDouble(1, latitude);
 			stmt.setDouble(2, longitude);
+			stmt.setDouble(3, latitude);
+			stmt.setDouble(4, longitude);			
 			res = stmt.executeQuery();
 			result = convertResultset(res);