A parallel transitive closure algorithm using hash-based clustering

Abstract

The importance of the performance problem brought about by the evaluation of recursive queries brings one to consider parallel execution strategies for the transitive closure operation. Such strategies constitute one of the keys to efficiency in a very large data base environment. In this paper we present a transitive closure algorithm. The innovative aspects of this algorithm concern: 1) the possibility of working with a reasonable amount of memory space without creating extra Inputs/Outputs; 2) the use of on-disk clustering accomplished by double hashing; and 3) the parallelization of the transitive closure operation. The processing time is reduced by a factor of p, where p is the number of processors allocated for the operation. Communication times remain limited; a cyclic organization eliminates the need for serialization of transfers. The evaluation shows the importance of the benefits of a parallel transitive closure execution.