ST_StartPoint — Returns the first point of a LINESTRING geometry as a POINT.


geometry ST_StartPoint(geometry geomA);


Returns the first point of a LINESTRING or CIRCULARLINESTRING geometry as a POINT or NULL if the input parameter is not a LINESTRING or CIRCULARLINESTRING.

This method implements the SQL/MM specification. SQL-MM 3: 7.1.3

This function supports 3d and will not drop the z-index.

This method supports Circular Strings and Curves


Changed: 2.0.0 no longer works with single geometry multilinestrings. In older versions of PostGIS -- a single line multilinestring would work happily with this function and return the start point. In 2.0.0 it just returns NULL like any other multilinestring. The older behavior was an undocumented feature, but people who assumed they had their data stored as LINESTRING may experience these returning NULL in 2.0 now.


SELECT ST_AsText(ST_StartPoint('LINESTRING(0 1, 0 2)'::geometry));
 POINT(0 1)
(1 row)

SELECT ST_StartPoint('POINT(0 1)'::geometry) IS NULL AS is_null;
(1 row)

--3d line
SELECT ST_AsEWKT(ST_StartPoint('LINESTRING(0 1 1, 0 2 2)'::geometry));
 POINT(0 1 1)
(1 row)

-- circular linestring --
SELECT ST_AsText(ST_StartPoint('CIRCULARSTRING(5 2,-3 1.999999, -2 1, -4 2, 5 2)'::geometry));
 POINT(5 2)

See Also

ST_EndPoint, ST_PointN