PostGIS ST_Contains Function Error

Question

I am running the below query and try to identify the end point of a line with gid 338 on the polygon's boundary with gid 1456 but got some error message:

SELECT public.st_contains((Select public.st_EndPoint(the_geom) from lines where gid=338),(select public.st_Boundary(the_geom) from polygons where gid=1456))

The error message:

> ERROR:  function _st_contains(public.geometry, public.geometry) does
> not exist LINE 1: SELECT $1 && $2 AND _ST_Contains($1,$2)
> HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
> QUERY:  SELECT $1 && $2 AND _ST_Contains($1,$2) CONTEXT:  SQL function
> "st_contains" during inlining

If I run

SELECT ST_Contains(ST_GeomFromText('LINESTRING(0 0, 5 5, 10 10)'),ST_GeomFromText('point(3 3)'));

It will return "t" as the correct value.

Answer 1

Edited

Take a look at the doc: http://postgis.net/docs/manual-2.1/ST_Contains.html

Sorry, I misread your question first.

Interesting that it didn't work with your first syntax but with _st_contains().

But the way you do it is not the way you usually do it in SQL.

Your query will run with indexes if you rewrite to something like:

SELECT public.st_contains(st_EndPoint(lines.the_geom), st_Boundary(polygons.the_geom))
FROM lines, polygons 
WHERE lines.gid=338 and polygons.gid=1456;

May I guess that what you want is tho find all cases where the lines endpoints is on the boundary of a polygon. That you do with something like:

SELECT lines.gid, polygon.gid 
FROM lines INNER JOIN polygons 
ON ST_Contains(st_EndPoint(lines.the_geom), ST_Bounadary(polygons.the_geom));