OBDA Constraints for Effective Query Answering (Extended Version)
arXiv: Databases, Volume abs/1605.04263, 2016.
In Ontology Based Data Access (OBDA) users pose SPARQL queries over an ontology that lies on top of relational datasources. These queries are translated on-the-fly into SQL queries by OBDA systems. Standard SPARQL-to-SQL translation techniques in OBDA often produce SQL queries containing redundant joins and unions, even after a number of ...More
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