GeoSPARQL Reference

pg_ripple v0.25.0 implements a subset of GeoSPARQL 1.1 using PostGIS as the underlying geometry engine. All geo functions gracefully degrade (returning false or NULL) when PostGIS is not installed.

Requirements

Requirement	Version
PostGIS	2.5+ (3.x recommended)
PostGIS SQL extension	Must be installed in the same database

Check availability:

SELECT EXISTS(SELECT 1 FROM pg_proc WHERE proname = 'st_geomfromtext') AS postgis_available;

Geometry Representation

Geometries are stored as WKT (Well-Known Text) literals in the RDF triple store. Use N-Triples or Turtle syntax to load them:

SELECT pg_ripple.load_ntriples(
    '<https://geo.example/city/berlin> <https://www.w3.org/ns/locn#geometry>
     "POINT(13.404954 52.520008)" .'
);

The geo:wktLiteral datatype IRI is stored as a regular literal; the WKT string is passed directly to ST_GeomFromText() at query time.

Topological Relation Functions (FILTER context)

These functions are used in FILTER(...) clauses and return true or false.

SPARQL IRI	PostGIS equivalent	Description
`geo:sfIntersects(a, b)`	`ST_Intersects(…)`	Geometries share at least one point
`geo:sfContains(a, b)`	`ST_Contains(…)`	A completely contains B
`geo:sfWithin(a, b)`	`ST_Within(…)`	A is completely within B
`geo:sfOverlaps(a, b)`	`ST_Overlaps(…)`	Geometries overlap
`geo:sfTouches(a, b)`	`ST_Touches(…)`	Geometries touch at boundary
`geo:sfCrosses(a, b)`	`ST_Crosses(…)`	Geometries cross
`geo:sfDisjoint(a, b)`	`ST_Disjoint(…)`	Geometries share no points
`geo:sfEquals(a, b)`	`ST_Equals(…)`	Geometries are spatially equal
`geo:ehIntersects(a, b)`	`ST_Intersects(…)`	Egenhofer intersection
`geo:ehContains(a, b)`	`ST_Contains(…)`	Egenhofer contains
`geo:ehCoveredBy(a, b)`	`ST_CoveredBy(…)`	A is covered by B
`geo:ehCovers(a, b)`	`ST_Covers(…)`	A covers B

Namespace prefix: http://www.opengis.net/def/function/geosparql/

Example: Find intersecting geometries

PREFIX geo: <http://www.opengis.net/def/function/geosparql/>
SELECT ?city WHERE {
  ?city <https://www.w3.org/ns/locn#geometry> ?geom .
  FILTER(geo:sfIntersects(?geom, "POLYGON((13.0 52.0, 14.0 52.0, 14.0 53.0, 13.0 53.0, 13.0 52.0))"))
}

Measurement Functions (BIND context)

These functions are used in BIND(...) clauses and return numeric or WKT values.

SPARQL IRI	Returns	Description
`geof:distance(a, b, unit)`	`xsd:double` (metres)	Geodetic distance between two geometries
`geof:area(a, unit)`	`xsd:double` (m²)	Surface area of a geometry
`geof:boundary(a)`	WKT literal	Boundary geometry as WKT string

The unit argument is accepted for API compatibility but all results are returned in SI base units (metres / square metres).

Example: Distance query

PREFIX geof: <http://www.opengis.net/def/function/geosparql/>
SELECT ?city ?dist WHERE {
  ?city <https://www.w3.org/ns/locn#geometry> ?geom .
  BIND(geof:distance(?geom, "POINT(13.404954 52.520008)",
                     <http://www.opengis.net/def/uom/OGC/1.0/metre>) AS ?dist)
  FILTER(?dist < 100000)
}
ORDER BY ?dist

Behaviour When PostGIS Is Absent

When PostGIS is not installed:

Topological filter functions evaluate to false — queries return zero rows
Measurement functions evaluate to NULL — BIND variables are unbound
No ERROR is raised; the query completes normally

This allows geospatial queries to be deployed to environments where PostGIS is an optional component.

Limitations

3D geometries (POINT Z, POLYGON Z) are stored as literals but PostGIS 2D functions will project them to 2D.
Coordinate reference system (CRS) handling: all geometries are assumed to be in WGS84 (SRID 4326) when passed to the geography cast for geof:distance and geof:area.
RDF-star quoted triples are not supported as geometry arguments.