Query execution optimization for clients of triple pattern fragments

Abstract

In order to reduce the server-side cost of publishing queryable Linked Data, Triple Pattern Fragments (TPF) were introduced as a simple interface to RDF triples. They allow for SPARQL query execution at low server cost, by partially shifting the load from servers to clients. The previously proposed query execution algorithm uses more HTTP requests than necessary, and only makes partial use of the available metadata. In this paper, we propose a new query execution algorithm for a client communicating with a TPF server. In contrast to a greedy solution, we maintain an overview of the entire query to find the optimal steps for solving a given query. We show multiple cases in which our algorithm reaches solutions with far fewer HTTP requests, without significantly increasing the cost in other cases. This improves the efficiency of common sparql queries against TPF interfaces, augmenting their viability compared to the more powerful, but more costly, SPARQL interface.