GetNodeByPoint — Find the id of a node at a point location
integer GetNodeByPoint(varchar atopology, geometry point, float8 tol
The function return an integer (id-node) given a topology, a POINT and a tolerance. If tolerance = 0 mean exactly intersection otherwise retrieve the node from an interval.
If there isn't a node at the point, it return 0 (zero).
If use tolerance > 0 and near the point there are more than one node it throw an exception.
If tolerance = 0, the function use ST_Intersects otherwise will use ST_DWithin.
Performed by the GEOS module.
These examples use edges we created in AddEdge
SELECT topology.GetNodeByPoint('ma_topo',geom, 1) As nearnode FROM ST_GeomFromEWKT('SRID=26986;POINT(227591.9 893900.4)') As geom; nearnode ---------- 2
SELECT topology.GetNodeByPoint('ma_topo',geom, 1000) As too_much_tolerance FROM ST_GeomFromEWKT('SRID=26986;POINT(227591.9 893900.4)') As geom; ----get error-- ERROR: Two or more nodes found