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ST_Length

Signature

DOUBLE ST_Length(GEOMETRY geom);

Description

Returns the length of geom:

  • Linear geometries return their length.
  • Areal geometries return their perimeter.
  • Others return 0.0.

Length is measured in the units of the spatial reference system.

Implements the OpenGIS Simple Features Implementation Specification for SQL version 1.2.1.

Examples

SELECT ST_Length('MULTIPOINT((4 4), (1 1), (1 0), (0 3)))');
-- Answer: 0.0

SELECT ST_Length('LINESTRING(2 1, 1 3, 5 2)');
-- Answer: 6.35917360311745

SELECT ST_Length('POLYGON((1 2, 4 2, 4 6, 1 6, 1 2))');
-- Answer: 14.0

SELECT ST_Length('MULTIPOLYGON(((0 2, 3 2, 3 6, 0 6, 0 2)),
                               ((5 0, 7 0, 7 1, 5 1, 5 0)))');
-- Answer: 20.0

SELECT ST_Length('GEOMETRYCOLLECTION(
                    MULTIPOINT((4 4), (1 1), (1 0), (0 3)),
                    LINESTRING(2 1, 1 3, 5 2),
                    POLYGON((1 2, 4 2, 4 6, 1 6, 1 2)))');
-- Answer: 20.35917360311745
See also