Name
ST_AddPoint — Adds a point to a LineString before point <position> (0-based index).
Synopsis
geometry ST_AddPoint(geometry linestring, geometry point);
geometry ST_AddPoint(geometry linestring, geometry point, integer position);
Description
Adds a point to a LineString before point <position> (0-based index). Third parameter can be omitted or set to -1 for appending.
Availability: 1.1.0
This function supports 3d and will not drop the z-index.
Examples
--guarantee all linestrings in a table are closed
--by adding the start point of each linestring to the end of the line string
--only for those that are not closed
UPDATE sometable
SET the_geom = ST_AddPoint(the_geom, ST_StartPoint(the_geom))
FROM sometable
WHERE ST_IsClosed(the_geom) = false;
--Adding point to a 3-d line
SELECT ST_AsEWKT(ST_AddPoint(ST_GeomFromEWKT('LINESTRING(0 0 1, 1 1 1)'), ST_MakePoint(1, 2, 3)));
--result
st_asewkt
----------
LINESTRING(0 0 1,1 1 1,1 2 3)