Abstract
With the rapid increase of RDF data, the SPARQL query processing has received much attention. Currently, most RDF databases store RDF data in a relational table called triple table and carry out several join operations on the triple tables for SPARQL query processing. However, the execution plans with many joins might be inefficient due to a large amount of intermediate data being passed between join operations. In this paper, we propose a triple filtering method called RP-Filter to reduce the amount of intermediate data. RP-Filter exploits the path information in the query graphs and filters the triples which would not be included in final results in advance of joins. We also suggest an efficient relational operator RFLT which filters triples by means of RP-Filter. Experimental results on synthetic and real-life RDF data show that RP-Filter can reduce the intermediate results effectively and accelerate the SPARQL query processing.