Querying RDF Data Stored in DBMS: SPARQL to SQL Conversion

This paper discusses the design and implementation of a tool for SPARQL to SQL conversion. The converter receives a SPARQL query which is then parsed and analyzed. All three current approaches to storing RDF data in RDMS (triple store, property tables, and vertical partitioning) are supported in this paper. Depending on the tool's configuration one of these methods is chosen and a proper SQL query is generated. After executing the SQL query and getting rows back from the database, the tool converts the result into SPARQL XML format. In the end this result is returned as an answer to the initial SPARQL query.