\pset null NULL
SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#1>'::rdf_iri;
 ?column? 
----------
 t
(1 row)

SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#2>'::rdf_iri;
 ?column? 
----------
 f
(1 row)

SELECT '<http://foo.bar#1>'::rdf_iri = NULL;
 ?column? 
----------
 NULL
(1 row)

SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#1>'::text;
 ?column? 
----------
 t
(1 row)

SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#2>'::text;
 ?column? 
----------
 f
(1 row)

SELECT '<http://foo.bar#1>'::text = '<http://foo.bar#1>'::rdf_iri;
 ?column? 
----------
 t
(1 row)

SELECT '<http://foo.bar#1>'::text = '<http://foo.bar#2>'::rdf_iri;
 ?column? 
----------
 f
(1 row)

SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#1>'::rdf_literal;
ERROR:  operator does not exist: rdf_iri = rdf_literal
LINE 1: SELECT '<http://foo.bar#1>'::rdf_iri = '<http://foo.bar#1>':...
                                             ^
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
SELECT '<http://foo.bar#1>'::rdf_literal = '<http://foo.bar#1>'::rdf_iri;
ERROR:  operator does not exist: rdf_literal = rdf_iri
LINE 1: SELECT '<http://foo.bar#1>'::rdf_literal = '<http://foo.bar#...
                                                 ^
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.