This system implements the SPARQL 1.1 Federated Query extension, by extending the OGSA-DAI/DQP system. The optimisation of these federated queries is done in SPARQL-DQP by identifying well-designed patterns in queries, as described in [1] and [2]. Using such patterns it is possible to apply rewriting rules to federated SPARQL queries and improve the execution time of the queries.

[1] J. Pérez, M. Arenas and C. Gutierrez, Semantics and complexity of SPARQL, TODS 34(3), 2009

[2] Semantics and optimization of the SPARQL 1.1 federation extension, Carlos Buil Aranda, Marcelo Arenas, Oscar Corcho. Extended Semantic Web Conference (ESWC2011), Semantic Data Management track, 2011. Best paper award. Download the paper here.

[3] Federating Queries in SPARQL1.1:Syntax, Semantics and Evaluation, Carlos Buil-Aranda, Marcelo Arenas, Oscar Corcho, Axel Polleres. Available here. Bibtex available here.

Semantics and optimization of the SPARQL 1.1 federation extension