How to query a postgres database to get all points within a 10km radius of certain coordinates

Question

I have a database of shops and in that database I have coordinates for these shops saved. I would like to get the list of shops in a 10km radius however I am not sure how to write the Postgres query since I am using Postgres database.

My database :

I am trying to add the query to a springboot geolocation microservice :

Repository code :

@Repository
public interface SellerGeolocationRepository extends CrudRepository<Seller_Geolocation, Long> {

    @Query(value="SELECT * FROM seller_geolocation_ms WHERE 
   // get coordinates that are in the vicinity
", nativeQuery = true)
        public Set<Seller_Geolocation> findAllSellersInRange(double longitude, double latitude);

    }

SellerObject :

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name = "seller_geolocation_ms")
public class Seller_Geolocation {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private static final long serialVersionUID = 2L;

    private double latitude;
    private double longitude;
    private String country;
    private String city;
    private String zipCode;
    private String town;
    private String address;
    private Long sellerId;
}

Answer 1

You can use the haversine formula, using your current coordinates (target_latitude_deg/longitude) and the column name (latitude_deg, longitude_deg), both expressed in degrees

SELECT * 
FROM myTable
WHERE acos(
       sin(radians(target_latitude_deg)) 
         * sin(radians(latitude_deg)) 
       + cos(radians(target_latitude_deg)) 
         * cos(radians(latitude_deg)) 
         * cos( radians(target_longitude_deg)
           - radians(longitude_deg))
       ) * 6371 <= 10;

Alternatively, have a look at the PostGIS extension

SELECT * 
FROM MyTable 
WHERE ST_Dwithin(geom, st_point(target_longitude, target_latitude,10000);

Answer 2

For this to work you will need to install postgis :

brew install postgis

afterwards you will need to install postgis on your postgres database " seller_geolocation_ms ":

   1. $ sudo -i -u postgres
   2. $ psql
   3. postgres=# \c seller_geolocation_ms;
   4. seller_geolocation_ms=# CREATE EXTENSION postgis;
   5. \q

After these steps postgis should be installed on your database. then the next thing to is to write the query on your Springboot repository interface like this:

@Repository
public interface SellerGeolocationRepository extends CrudRepository<Seller_Geolocation, Long> {

    @Query(value="SELECT * FROM seller_geolocation_ms WHERE ST_DWithin(cast(seller_geolocation_ms.location as geography),ST_SetSRID(ST_Point(?2, ?1),4326), 10000);", nativeQuery = true)
    public Set<Seller_Geolocation> findAllSellersInRange(double longitude, double latitude);

}

To get a more indepth understanding of how ST_DWithin please follow this link : here

Answer 3

Take a look at Postgres earthdistance , ther's also an example mentioned here However, you can use Postgis which has rich geospatial functions. If you want to calculate at business logic, use Haversine formula as explained in @JGH answer above.