This chapter describes simulation experiments conducted with the Update Algorithm, and presents the results from these experiments. The goal of the simulation was to gauge the expected performance of the update and query processing algorithms in a traditional database management system application. The implementation was tailored to this environment, and for that reason the techniques used and results obtained will apply only partially, if at all, to other application environments, such as knowledge-based artificial intelligence applications. In particular, the following assumptions and restrictions were made.

• Update syntax was modified and restricted, to encourage use of simple constructs.

• A fixed data access mechanism (query language) was assumed.

• A large, disk-resident database supplying storage for the relational theory was assumed.

• Performance was equated with the number of disk accesses required to perform queries and updates after a long series of updates, and the storage space required after a long series of updates.

These assumptions and restrictions are all appropriate to traditional database management scenarios; they will be discussed in more detail in later sections. We begin with a brief high-level description of the implemented system, and then examine its components in more detail. The chapter concludes with a description of the experimental results.

Overview

The Update Algorithm Version II was chosen for simulation.