Subqueries in SPARQL

Subqueries are a poweful feature which allows to enforce reuse, composition, rewriting and optimization in a query language. In this paper we perform a comprehensive study of the incorporation of subqueries into SPARQL. We consider the many possible choices as suggested by the experience of similar languages, as well as features that developers are incorporating and/or experimenting with. Our study includes the discussion in the SPARQL case of common design issues concerning subqueries (i.e., query correlation, scope of datasets, and optimization), show the interplay among them, and study their implications in terms of expressive power. Based on this study, we present an extension of SPARQL, with syntax and formal semantics, which incorporates all knwon types of subqueries in a modular fashion and preserving the original semantics.

• Type: Journal
• Year: 2011
• Where: AMW
• Authors: Renzo Angles, Claudio Gutierrez
• Keywords: AMW 2011, Common Design, Expressive Power, Formal Semantics, Knowledge Management