Calculate distance travelled using PostgreSQL query - postgresql

Question

I am using PostgreSQL to store the location of a user send to the server by my android app. I needed to find the total distance travelled by the user for a particular time duration.
The user location is stored in the following table :
CREATE TABLE userlocation
(
latitude character varying,
longitude character varying,
geopoint point,
userid integer,
locationtime timestamp
)
I retrieved the records and calculated the distance in java using the following haversine distance method :
public double getdistance(final double lat1, final double lon1, final double lat2, final double lon2, final char unit) {
final double theta = lon1 - lon2;
double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
+ Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
* Math.cos(deg2rad(theta));
dist = Math.acos(dist);
dist = rad2deg(dist);
dist = dist * 60 * 1.1515;
if (unit == 'K') {
dist = dist * 1.609344;
} else if (unit == 'N') {
dist = dist * 0.8684;
}
if (Double.isNaN(dist)) {
dist = 0.0;
}
return (dist);
}
However this calculation is time consuming especially while calculating the distance for multiple days as there are a lot of records. I decided to try doing the distance calculation at the database level to reduce the calculation time. I found the the following query which allows me to calculate the distance to a certain point :
SELECT latitude, longitude, geopoint <-> '19.23,72.89' AS distance FROM userlocation ORDER BY distance;
I tried to create a query that would either return the total distance traveled or atleast calculate the distance between two consecutive rows and store it in another column so that I calculate the sum in Java instead of the distance calculations.
I have tried searching for a solution but I have been unable to find one yet. Most of the questions on SO deal with distance calculation between two points.
I do not have PostGIS at the moment. Would it be possible to calculate distance in PostgreSQL or should I just continue with my current approach? In that case is there an alternative for reducing the distance calculation time.

Answer 1

I had the same problem last month.
I added the module Earthdistance to PostgreSQL. This plugin add functions to compute the great circle distances between two points.
Installation is simple:
CREATE EXTENSION "cube";
CREATE EXTENSION "earthdistance";
Hope that helps