Efficient Evaluation of Conjunctive Regular Path Queries Using Multi-way Joins

Recent analyses of real-world queries show that a prominent type of queries is that of conjunctive regular path queries. Despite the increasing popularity of this type of queries, only limited efforts have been invested in their efficient evaluation. Motivated by recent results on the efficiency of worst-case optimal multi-way join algorithms for the evaluation of conjunctive queries, we present a novel multi-way join algorithm for the efficient evaluation of conjunctive regular path queries. The hallmark of our algorithm is the evaluation of the regular path queries found in conjunctive regular path queries using multi-way joins. This enables the exploitation of regular path queries in the planning steps of the proposed algorithm, which is crucial for the algorithm's efficiency, as shown by the results of our detailed evaluation using the Wikidata-based benchmark WDBench. The results of this evaluation also show that our approach achieves a value of query mixes per hour that is 4.3 higher than the state of the art and that it outperforms all of the competing graph storage solutions in almost 70% of the benchmark's queries.