Query Conversion for Aggregate Operations in Distributed SPARQL Query Processing Using Summary Information

Abstract

Resource Description Framework (RDF) is widely used as a framework for uniformly describing resources on the web. RDF expresses various data with triples that consist of subject, predicate and object. Query information can be inquired using the standard query language called SPARQL. Since the amount of retrieval processing also increases for large-scale data, many processing performance improvement methods by distributed processing using multiple servers have been proposed. As for processing of queries that perform aggregations such as SPARQL duplication elimination and average value function, it is impossible to avoid an increase in throughput due to an increase in the amount of data. In this paper, we propose a query conversion processing method so that distributed processing method can be applied to queries including aggregation. In addition, based on a method using summary information of data for distributed processing, the results of the retrieval using the proposed method were evaluated using real data. As a result, we confirmed the speedup of the search process by distributed processing.