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Ultrawrap: SPARQL Execution on Relational Data

13 Pages Posted: 9 Jul 2018 Publication Status: Accepted

See all articles by Juan Sequeda

Juan Sequeda

University of Texas at Austin - Department of Computer Science

Daniel P. Miranker

University of Texas at Austin - Department of Computer Science

Abstract

The Semantic Web's promise of web-wide data integration requires the inclusion of legacy relational databases, i.e., the execution of SPARQL queries on RDF representation of the legacy relational data. 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. The experiment is embodied in a system, Ultrawrap, that encodes a logical representation of the database as an RDF graph using SQL views and a simple syntactic translation of SPARQL queries to SQL queries on those views. Thus, in the course of executing a SPARQL query, the SQL optimizer uses the SQL views that represent a mapping of relational data to RDF, and optimizes its execution. In contrast, related research is predicated on incorporating optimizing transforms as part of the SPARQL to SQL translation, and/or executing some of the query outside the underlying SQL environment.

Ultrawrap is evaluated using two existing benchmark suites that derive their RDF data from relational data through a Relational Database to RDF (RDB2RDF) Direct Mapping and repeated for each of the three major relational database management systems. Empirical analysis reveals two existing relational query optimizations that, if applied to the SQL produced from a simple syntactic translations of SPARQL queries (with bound predicate arguments) to SQL, consistently yield query execution time that is comparable to that of SQL queries written directly for the relational representation of the data. The analysis further reveals the two optimizations are not uniquely required to achieve a successful wrapper system. The evidence suggests effective wrappers will be those that are designed to complement the optimizer of the target database.

Keywords: Semantic Web, Relational Databases, SPARQL, SQL, RDF, RDB2RDF

Suggested Citation

Sequeda, Juan and Miranker, Daniel P., Ultrawrap: SPARQL Execution on Relational Data (2013). Journal of Web Semantics First Look, Available at SSRN: https://ssrn.com/abstract=3199073 or http://dx.doi.org/10.2139/ssrn.3199073

Juan Sequeda (Contact Author)

University of Texas at Austin - Department of Computer Science ( email )

2317 Speedway, Stop D9500
Austin, TX
United States

Daniel P. Miranker

University of Texas at Austin - Department of Computer Science ( email )

2317 Speedway, Stop D9500
Austin, TX
United States

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