SPARQL-to-SQL on Internet of Things Databases and Streams
A paper by Eugene Siow, Thanassis Tiropanis and Wendy Hall describing an optimisation to a data storage and query technique which more than doubles performance.
Articles about RDF
SPARQL Query Rewriting for Implementing Data Integration over Linked Data
Research paper presenting an algorithm for RDF data mediation by Gianluca Correndo, Manuel Salvadores, Ian Millard, Hugh Glaser and Nigel Shadbolt