The Semantic Web’s promise to achieve web-wide data integration requires the inclusion of legacy
relational data as RDF, which, in turn, requires the execution of SPARQL queries on the legacy relational
database. In this research, we explore a hypothesis: existing commercial relational databases already subsume the
algorithms and optimizations needed to support effective SPARQL execution on existing relationally stored data .
Ultrawrap is a Relational Database to RDF (RDB2RDF) system, which encodes a logical representation of the
database as a graph using SQL views and a simple syntactic translation of SPARQL queries to SQL queries on
those views. Thus, in the course executing a SPARQL query, the SQL optimizer both instantiates a mapping of
relational data to RDF and optimizes its execution. Other approaches, such as D2RQ, typically implement aspects of query
optimization and execution outside the SQL environment.
Ultrawrap has been evaluated with the Barton and Berlin SPARQL Benchmark across the three major relational database management systems.
We identify two important optimizations: detection of unsatisfiable conditions and self-join elimination, such
that, when applied, SPARQL queries execute at nearly the same speed as semantically equivalent native SQL
Ultrawrap is currently being commercialized by Capsenta.
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