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D2R-Q

D2R-Q. Work together with Andy, Chris and Kevin Goal: Query huge, live, non-RDF data bases with RDQL Allow access to existing databases Allow a more efficient storage of application specific RDF data Approach: Develop a declarative mapping language, that allows to

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D2R-Q

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  1. D2R-Q • Work together with Andy, Chris and Kevin • Goal: Query huge, live, non-RDF data bases with RDQL • Allow access to existing databases • Allow a more efficient storage of application specific RDF data • Approach: • Develop a declarative mapping language, that allows to • rewrite RDQL and find(spo) queries to application specific SQL queries. • Redesign my D2R MAP language • Implement it as a Jena graph

  2. D2R-Q Architecture RDFApp Query +Update Query App-specificdatabase Jena extended with D2R-Q Graph Non-RDFApp Joseki Uses D2R-Q MAP

  3. iswc:Person iswc:name DtPropertyBridge uriPattern iswc:email ObjPropertyBridge ClassMap:Person iswc:authorOf ObjPropertyBridge rdf:type Datasource 1 ObjPropertyBridge owl:sameAs ObjPropertyBridge iswc:title DtPropertyBridge ClassMap:Paper uriPattern iswc:abstract DtPropertyBridge iswc:Paper iswc:topName DtPropertyBridge iswc:topDescr. DtPropertyBridge ClassMap:Topic Datasource 2 uriPattern rdf:type iswc:Topic Structure of a D2R-Q MAP

  4. Example • Part of a map about authors, papers and conferences: :InProceedings rdf:type rdfs:Class ; d2r:classMap db1:InProceedings . db1:InProceedings rdf:type d2r:ClassMap; d2r:uriPattern "http://www.example.org/ db01#Paper@@Papers.PaperID@@"; d2r:dataStorage db1:Database1 . :title rdf:type rdf:Property ; d2r:propertyBridge db1:inProceedingsTitle . db1:inProceedingsTitle rdf:type d2r:DatatypePropertyBridge ; d2r:column "Papers.Title" ; d2r:belongsToClassMap db1:InProceedings ; d2r:dataType dtype:string . :author rdf:type rdf:Property ; d2r:propertyBridge db1:inProceedingsAuthor. db1:inProceedingsAuthor rdf:type d2r:ObjectPropertyBridge ; d2r:join "Papers.PaperID = Rel_Person_Paper.PaperID" ; d2r:join "Rel_Person_Paper.PaperID = Persons.PerID" ; d2r:belongsToClassMap db1:InProceedings; d2r:refersToClassMap db1:PersonsClassGroupMap .

  5. Example Query find(s p o) • Find (ANY, iswc:title, “RDF in XML“) • Algorithm • Look at Predicate • Find ClassMaps • Get ColumnNames • Get Tables • Execute SQL • Return results • SQL :InProceedings rdf:type rdfs:Class ; d2r:classMap db1:InProceedings . db1:InProceedings rdf:type d2r:ClassMap; d2r:uriPattern "http://www.example.org/ db01#Paper@@Papers.PaperID@@"; d2r:dataStorage db1:Database1 . :title rdf:type rdf:Property ; d2r:propertyBridge db1:inProceedingsTitle . db1:inProceedingsTitle rdf:type d2r:DatatypePropertyBridge ; d2r:column "Papers.Title" ; d2r:belongsToClassMap db1:InProceedings ; d2r:dataType dtype:string. SELECT Papers.PaperIDFROM PapersWHERE Papers.Title = “RDF in XML”;

  6. Example Query find(s p o) with a Many-to-Many Join • Find(ANY, iswc:author, http//:www.persons.org#P1234) • Algorithm • Look at Predicate • Find ClassMaps • Find ReferedMaps • Get ColumnNames • Get Tables • Execute SQL • SQL :author rdf:type rdf:Property ; d2r:propertyBridge db1:inProceedingsAuthor. db1:inProceedingsAuthor rdf:type d2r:ObjectPropertyBridge ; d2r:join "Papers.PaperID = Rel_Person_Paper.PaperID" ; d2r:join "Rel_Person_Paper.PaperID = Persons.PerID" ; d2r:belongsToClassMap db1:InProceedings; d2r:refersToClassMap db1:PersonsClassMap . SELECT Papers.PaperIDFROM Papers, Persons, Rel_Person_Paper WHERE Papers.PaperID = Rel_Person_Paper.PaperID AND Rel_Person_Paper.PaperID = Persons.PerID AND Persons. PersonID = 1234;

  7. Query Performance find(s p o) • find (?x p o) OK (I guess) • find (?x p ?z) OK • find (s p ?z) OK • find (s p o) OK • find (s ?x ?y) slow • find (?x ?y o) very slow • find (?x ?y ?z) db dump  Use Pattern groups, because they contain more usable information.

  8. Pattern Groups • Second step: Use Pattern groups because they contain more information useable for query optimization. • WHERE part of a RDQL query • Find all author with papers at "TheConference" results in one SQL statement. (?x iswc:eventTitle "TheConference") (?y iswc:conference ?x) (?y iswc:author ?z)

  9. D2R-Q: Status Quo • Language designed • Algorithms designed • Paper tests with two relatively complex ontologies and database schemata (including taxonomies and many-to-many relationships). • Implementation started • D2RQGraph implements Jena Graph • D2RQQueryHandler implements Jena QueryHandler. • D2R-Q will be available under an open source license sometime in May.

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