  In this paper, we propose a new approach for fast processing of SPARQL
queries on large RDF datasets containing RDF quadruples (or quads). Our
approach called RIQ employs a decrease-and-conquer strategy: Rather than
indexing the entire RDF dataset, RIQ identifies groups of similar RDF graphs
and indexes each group separately. During query processing, RIQ uses a novel
filtering index to first identify candidate groups that may contain matches for
the query. On these candidates, it executes optimized queries using a
conventional SPARQL processor to produce the final results. Our initial
performance evaluation results are promising: Using a synthetic and a real
dataset, each containing about 1.4 billion quads, we show that RIQ outperforms
RDF-3X and Jena TDB on a variety of SPARQL queries.
