ST_Distance

For input geometries, ST_Distance returns the minimum Euclidean distance between the 2D projections of the two input geometry values.

For 3DM, 3DZ, 4D geometries, ST_Distance returns the Euclidean distance between the 2D projections of two input geometry values.

For input geographies, ST_Distance returns the geodesic distance of the two 2D points. The unit of distance is in meters. For geographies other than points and empty points an error is returned.

Syntax

ST_Distance(geo1, geo2)

Arguments

geo1

A value of data type GEOMETRY or GEOGRAPHY, or an expression that evaluates to a GEOMETRY or GEOGRAPHY type. The data type of geo1 must be the same as geo2.

geo2

A value of data type GEOMETRY or GEOGRAPHY, or an expression that evaluates to a GEOMETRY or GEOGRAPHY type. The data type of geo2 must be the same as geo1.

Return type

DOUBLE PRECISION in the same units as the input geometries or geographies.

If geo1 or geo2 is null or empty, then null is returned.

If geo1 and geo2 don't have the same value for the spatial reference system identifier (SRID), then an error is returned.

If geo1 or geo2 is a geometry collection, then an error is returned.

Examples

The following SQL returns the distance between two polygons.

SELECT ST_Distance(ST_GeomFromText('POLYGON((0 2,1 1,0 -1,0 2))'), ST_GeomFromText('POLYGON((-1 -3,-2 -1,0 -3,-1 -3))'));

  st_distance
-----------
1.4142135623731               

The following SQL returns the distance (in meters) between the Brandenburg Gate and the Reichstag building in Berlin using a GEOGRAPHY data type.

SELECT ST_Distance(ST_GeogFromText('POINT(13.37761826722198 52.516411678282445)'), ST_GeogFromText('POINT(13.377950831464005 52.51705102546893)'));

   st_distance
------------------
 74.64129172609631