The predicates below enumerate the basic objects of the RDF store.
Most of these predicates also enumerate objects that are not associated
to any currently visible triple. Objects are retained as long as they
are visible in active queries or snapshots. After that, some are
reclaimed by the RDF garbage collector, while others are never
reclaimed.
- [nondet]rdf_subject(?Resource)
- True if Resource appears as a subject. This query respects
the visibility rules implied by the logical update view.
- See also
- rdf_resource/1.
- [nondet]rdf_resource(?Resource)
- True when Resource is a resource used as a subject or object
in a triple.
This predicate is primarily intended as a way to process all
resources without processing resources twice. The user must be aware
that some of the returned resources may not appear in any
visible triple.
- [nondet]rdf_current_predicate(?Predicate)
- True when Predicate is a currently known predicate.
Predicates are created if a triples is created that uses this predicate
or a property of the predicate is set using rdf_set_predicate/2.
The predicate may (no longer) have triples associated with it.
Note that resources that have rdf:type rdf:Property
are not automatically included in the result-set of this predicate,
while all resources that appear as the second argument of a
triple are included.
- See also
- rdf_predicate_property/2.
- [nondet]rdf_current_literal(-Literal)
- True when Literal is a currently known literal. Enumerates
each unique literal exactly once. Note that it is possible that the
literal only appears in already deleted triples. Deleted triples may be
locked due to active queries, transactions or snapshots or may not yet
be reclaimed by the garbage collector.
- [nondet]rdf_graph(?Graph)
- True when Graph is an existing graph.
- [nondet]rdf_current_ns(:Prefix,
?URI)
-
- deprecated
- Use rdf_current_prefix/2.