Prefetching and caching for query scheduling in a special class of distributed applications

We analyze the scheduling aspects of database queries submitted to an abstract model of a very large distributed system. The essential elements of this model are: (a) a finite number of identical processing nodes with limited storage capacity, (b) a finite number of queries to be serviced, (c) a very large read-only data set that is shared by all queries and (d) a fixed inter-node communication latency. This framework models an important class of applications that use distributed processing of very large data sets. Examples of these applications exist in the very large database and multimedia problem domains. To meet the objective of minimizing flow time of queries while exploiting inter-query locality, various heuristics are proposed and evaluated through extensive simulation.