. The problem of predicting the performance of a parallel relational DBMS for a set of queries applied to a particular data set on a shared nothing parallel architecture without transferring the application to a parallel system is a challenging one. An analytical approach has been developed to assist with this task and has been applied to the ICL GoldRush machine, a parallel machine with a shared-nothing architecture. This paper describes how the Oracle Parallel Server and the Parallel Query Option are modelled by the method and compares the predictions of the model against actual measurements obtained. Keywords: Analytical modelling,parallel Oracle, performance prediction, parallel database 1. Introduction The inherent parallelism in relational databases is well suited to parallel computer technology and commercial interest in the use of parallel computers for running relational database systems has been growing . A number of parallel database systems running on different paralle..