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Learn how to apply DAWG test cases in Semantic Bridge for Relational Databases (SBRD), translating SPARQL to SQL efficiently using Jena. Explore data conversion, running tests, query support, and future steps in ensuring SPARQL compliance.
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Using the DAWG Test Cases with Relational Databases Matthew Gheen mgheen@mcdonaldbradley.com October 26, 2007
Agenda • Introduction • Running the tests • Results • Next Steps • Discussion
Introduction • Semantic Bridge for Relational Databases (SBRD) • Translates SPARQL to SQL • Only uses Jena to build models • Tool validation • Use the DAWG test cases • Creation of tool to adapt the test cases • rdf2sql
Introduction • DAWG Test Cases – Revision 1 • Set of tests used to demonstrate support for SPARQL • 170 test are relevant to SBRD • Has data • Asks a semantically correct question • Written using latest SPARQL syntax • Written by several people, all in different styles • ttl, n3 • Result and data files used for multiple tests
Running the Tests • Data conversion • Created SQL table creation and insert statements for all data files • Untyped variables _:c rdf:type foaf:Person ; foaf:mbox <mailto:fred@work.example> ; foaf:name "Fred" . _:e foaf:name "Bob" . • Multiple values for same column and row _:a foaf:name "Robert"@EN. _:a foaf:name "Roberto"@ES.
Running the Tests • Columns with more than one type _:f foaf:name "John" ; ex:empId [ ex:number "29"^^xsd:integer ] . _:g foaf:name "Dirk" ; ex:empId <http://example.org/dirk01> . • URI predicate that does not refer to another existing table. • Creates a foreign key to nowhere • <mailto:alice@work.example> is a URI • Converted to String values to prevent foreign keys to nowhere
Running the Tests • The Queries • Keywords not supported • ASK, UNSAID, DESCRIBE, and ORDER BY • Variable predicates • ?x ?y ?z • Tests for Unicode support and bad SPARQL syntax • Not SBRD functionality tests, only tests Jena. • No support for untrusted graphs • Querying data loaded from a file specified in the query
Results • 24 of 170 DAWG tests can be used for SBRD
Next Steps • Create a new set of DAWG test cases for RDF to SQL adaptors • Subset of the full test suite that is relevant to relational databases • Reusable for current and upcoming tools • Ensures SPARQL compliance as specification matures