SELECT extversion FROM pg_extension WHERE extname = 'rdf_fdw';

CREATE SERVER fs FOREIGN DATA WRAPPER rdf_fdw
OPTIONS (endpoint 'http://example.com/sparql');

CREATE FOREIGN TABLE ft (
  s rdfnode OPTIONS (variable '?s'),
  p rdfnode OPTIONS (variable '?p'),
  o rdfnode OPTIONS (variable '?o')
) SERVER fs OPTIONS 
  (sparql 'SELECT ?s ?p ?o WHERE { }');

ALTER EXTENSION rdf_fdw UPDATE TO '2.2';
SELECT extversion FROM pg_extension WHERE extname = 'rdf_fdw';

ALTER EXTENSION rdf_fdw UPDATE TO '2.3';
SELECT extversion FROM pg_extension WHERE extname = 'rdf_fdw';

DROP SERVER fs CASCADE;