Experimenting with radius search using postgis.

radius_search.sql

/* Enable postgis */
CREATE EXTENSION  IF NOT EXISTS postgis;

CREATE TABLE ex1 (
  id VARCHAR(10) NOT NULL,
  loc geography(POINT, 4326)
);

CREATE INDEX  ex1_loc_gix ON  ex1  USING GIST (loc);

INSERT INTO ex1 (id, loc) VALUES ('1', st_geographyfromtext('point(59.3497989 18.0706644)'));
INSERT INTO ex1 (id, loc) VALUES ('2', st_geographyfromtext('point(59.3463858 18.0659866)'));
INSERT INTO ex1 (id, loc) VALUES ('3', st_geographyfromtext('point(59.3324452 18.1188154)'));

SELECT id, st_astext(loc), st_distance(loc, st_geographyfromtext('point(59.3497989 18.0706644)')) FROM ex1;

SELECT id, st_astext(loc), st_distance(loc, st_geographyfromtext('point(59.3497989 18.0706644)')) FROM ex1
  WHERE st_distance(loc, st_geographyfromtext('point(59.3497989 18.0706644)')) <= 2000;

SELECT id, st_astext(loc), st_distance(loc, st_geographyfromtext('point(59.3497989 18.0706644)')) FROM ex1
  WHERE st_dwithin(loc, st_geographyfromtext('point(59.3497989 18.0706644)'), 2000);

DELETE FROM ex1;