HP 3000 Manuals HP 3000 Manuals
Chapter 3 Physical Design Physically, an ALLBASE/SQL DBEnvironment is a collection of files for the storage of databases. The physical design process helps you compute the storage requirements for the tables, indexes, and other objects that emerge at the end of the logical design process. This chapter describes several steps that are involved in developing an appropriate physical design for your DBEnvironments: * Calculating storage for database objects * Calculating storage for the system catalog * Calculating storage for logging * Calculating temporary disk space * Estimating shared memory requirements * Estimating the number of transactions * Implementing the design Before designing physical storage, you must first establish the logical design of your databases. The layout of the tables, the number of columns and column sizes, the column data types, the number and types of indexes, and the estimated number of rows per table are all factors that affect physical design. You should also have an idea of how the the tables are going to be used, since you can design physical storage to optimize performance. Physical design also requires an understanding of ALLBASE/SQL files. Therefore, this chapter also describes the characteristics of DBEFiles and log files while presenting guidelines on determining storage requirements. Familiarity with the MPE/iX file system will also help you during the physical design phase.