The evaluation of access costs in object databases

Unfortunately, there is at present nothing to assist the system architect at design-time to determine whether a proposed architecture based on an object-oriented database system will perform as required. The problem is complex, the choice of suitable modelling approach difficult, and a construction of a model is often abstruse. In this paper we concentrate on a major model component: that describing the access of objects in a centralised database. We present the background for the research (modern corporate IS architectures), the choices we have made, the prototype design, and the mathematical model of the cost of object database access. We conclude the paper by describing a validation of the model and how it can be generalised. The paper has a number of objectives: first, to dispel the myth that performance modelling of object-oriented systems is an immensely difficult task; second, to show that techniques which have been in existence for some time for modelling are applicable, with some modification, to aspects of object-oriented database performance prediction; and, third, to detail a specific case study of access cost modelling which provides enough information to be replicated by other workers across a number of object-oriented database products.