Parallel algorithms for database operations and a database operation for parallel algorithms

This paper establishes some significant links between two areas: (i) relational parallel database systems; and (ii) the design and analysis of parallel algorithms. The paper begins with a fundamental but very simple observation: implementing a JOIN operation in the context of relational parallel database systems is at least as expensive as implementing an arbitrary PRAM computation. Thus, the efficiency with which a given parallel computer can support a parallel relational database where JOINs are fairly frequent is strongly related to the efficiency with which that computer can support the PRAM as one of its programmer´s models. The main technical contribution is an efficient parallel algorithm for the JOIN operation on a model where, in order to use the available bandwidth effectively, communication has to be performed in large blocks