rdf_estimate_complexity/4

Documentation
- Reference manual
- Packages
  - SWI-Prolog Semantic Web Library 3.0
    - Two RDF APIs
      - library(semweb/rdf_db): The RDF database
        
        Miscellaneous predicates
        
        rdf_bnode/1
        
        rdf_source_location/2
        
        rdf_generation/1
        
        rdf_estimate_complexity/4
        
        rdf_statistics/1
        
        rdf_match_label/3
        
        lang_matches/2
        
        lang_equal/2
        
        rdf_reset_db/0
        
        rdf_version/1

Availability::- use_module(library(semweb/rdf_db)).

rdf_estimate_complexity(?Subject, ?Predicate, ?Object, -Complexity)

Return the number of alternatives as indicated by the database internal hashed indexing. This is a rough measure for the number of alternatives we can expect for an rdf_has/3 call using the given three arguments. When called with three variables, the total number of triples is returned. This estimate is used in query optimisation. See also rdf_predicate_property/2 and rdf_statistics/1 for additional information to help optimizers.