Parallelism in a Main-Memory DBMS: The Performance of PRISMA/DB

This paper evaluates the performance of the parallel, main-memory DBMS, PRISMA/DB. First, an abstract architecture for parallel query execution is presented. A performance model for the execution of simple relational operations on this architecture is developed. The parameters in the model are set using experiments on PRISMA/DB and the performance of PRISMA/DB is analized in the context of the model. Several conclusions can be drawn from the model combined with the results of the performance experiments. Firstly, the performance of PRISMA/DB appears to be competitive with respect to other systems. Secondly, the developed model can explain the results from the performance experiments to a large extent. Also, it is concluded that observed linear speedup for small numbers of processors cannot always be extrapolated to larger numbers of processors. Finally, it is concluded that the optimal number of processors for the parallel execution of an operation is smaller for a mainmemory system than for a disk-based system. The results of this study can be used to design data fragmentation strategies for large parallel machines. ‘The work reported in this paper was conducted as part of the PRISM.4 project, a joint effort with Philips Research Laboratories Eindhoven, partially supported by the Dutch “Stimuleringsprojectteam Informaticaonderzoek (SPIN)“. Permission to copy without fee all or part of this material is grantedprovided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from