Advanced SQL-to-SPARQL Query Transformation Approach

Abstract

No one can deny the emergence of semantic web technologies with their considerable performance in data management offering a better cooperation between people and computers, but unfortunately, relational databases are still the most used; therefore establishing a connection between them becomes an active topic aiming to bridge the gap between the both heterogeneous systems. Regarding the interoperability between their query languages, more precisely, SQL-to-SPARQL query transformation direction, some solutions have been explored to ensure this conversion, but all these approaches have the same gap because they start the mapping process before analyzing and optimizing the input SQL query; this weakness has motivated us to add a pretreatment phase aiming to optimize some SQL components with a specific focus on Left and Right Outer Join command(s) generating the most complex component SPARQL query (Optional pattern(s)) in order to reduce complexity of the output SPARQL query.