H.: Distributing a Database for Parallelism

In this paper we treat the problem of sub-dividing a database and allocating the fragments to the sites in a distributed database system in order to maximize non-.duplicative parallelism. Our goal is to establish a'conceptual framework for distributing data without being camnitted to specific cost models. We introduce,the concept of "local sufficien-cy " as a measure of parallelism, and show how certain'classes of queries lead naturally to irredundant partitions of a database that are locallv sufficient..For classes of aueries for which no frredundant distribution is'locally sufficient, we offer ways to introduce redundancy in achieving local sufficiency 1