This video presents an extension of the ontology-based data access platform Ontop that supports answering SPARQL queries under the OWL 2 QL direct semantics entailment regime for data instances stored in relational databases. On the theoretical side, we show how any input SPARQL query, OWL 2 QL ontology and R2RML mappings can be rewritten to an equivalent SQL query solely over the data. On the practical side, we present initial experimental results demonstrating that by applying Ontop technologies the system produces scalable SQL queries.
URL: http://videolectures.net/iswc2014_kontchakov_sparql_queries/
Keywords: Ontop, Entailment Regimes, Ontology-Based Data Access (ODBA), Query rewriting, RDBMS, Relational model
Author: Kontchakov, Roman
Date created: 2014-12-19 05:00:00.000
Language: http://id.loc.gov/vocabulary/iso639-2/eng
Time required: P20M
- Knows methods such as Direct Mapping of Relational Data to RDF (2012) for transforming data from the relational model (keys, values, rows, columns, tables) into RDF graphs.
- Understands how to combine and filter graph patterns using operators such as UNION, OPTIONAL, FILTER, and MINUS.
- Understands the difference between SQL query language (which operates on database tables) and SPARQL (which operates on RDF graphs).
- Uses common entailment regimes and understands their uses.