I am using PostgreSQL 9.3 and PostGIS 2.1.I imported a shapefile into my database. In that the_geom data type is "LINESTRING". Now I need a query to find the lines within a given radius for a particular latitude, longitude.

For example:

Consider I have latitude and longitude (12.4444 78.898900) for the given radius of 5000 meters I have to get the line details.

I tried a lot regarding this, I can't find a solution. Help me to solve this.

1 Answer 1


You'll find it easier to reason about your problem (coordinates in lon/lat, parameters in meters) if you work using the geography type rather than the geometry type. Geography type takes in lon/lat coordinates, but lets you ask questions and get answers in metric units.

ALTER TABLE mytable ALTER COLUMN the_geom TYPE geography USING geography(the_geom);
ALTER TABLE mytable RENAME COLUMN the_geom TO geog;
SELECT * FROM mytable WHERE ST_DWithin(geog, 'POINT(78.898900 12.4444)'::geography, 5000);

Note that the coordinate order for PostGIS is x/y, lon/lat. The x or longitude always comes first.

  • .i am trying to create index for geog column but it showing error "ERROR: index row requires 11488 bytes, maximum size is 8191" what i have to do for that..
    – Subburaj
    May 13, 2014 at 6:27
  • You're probably using the btree index binding, not the GIST. Correct syntax: CREATE INDEX myidx ON mytable USING GIST (mygeocolumn) May 13, 2014 at 16:41

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