Fault-tolerant computation of distributed regular path queries

Regular path queries are the building block of almost any mechanism for querying semistructured data. Despite the fact that the main applications of such data are distributed, there are only few works dealing with distributed evaluation of regular path queries. In this paper we present a message-efficient and truly distributed algorithm for computing the answer to regular path queries in a multi-source semistructured database setting. Our algorithm is general as it works for the larger class of weighted regular path queries on weighted semistructured databases. Also, we show how to make our algorithm fault-tolerant to smoothly work in environments prone to process (or machine) failures. This is very desirable in a grid setting, which is today’s new paradigm of distributed computing, and where one does not have full control over machines that can unexpectedly leave in the middle of computation.