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Show CHAPTER 4 THE DESIGN OF A VIRTUAL DATABASE SYSTEM In Chapter 3, an overview of a virtual database for the HELP System was presented. This chapter contains a discussion of the design of this virtual database system. The system that was developed is a prototype for the system that will be developed and installed at LDS Hospital. The prototype system differs from the intended initial production version in two ways. First, only two of the access paths into the ID file were included in the prototype version. This is sufficient to demonstrate the mechanism used to emulate the ID-file access paths. Additional access paths can be added to the prototype easily. The standard HELP database provides 17 access paths into the ID file. The production version of the virtual database for the HELP System will support all the defined access paths. Second, the prototype system only contains the data of 435 admissions to the hospital. This set of patient data contains all the patients that were discharged from LDS Hospital during a four-day period. One reason for the small size of the prototype database was the limited amount of disk storage space available on the computer that was used for the physical database. The volume of data used for the prototype database was adequate to demonstrate the feasibility and practicality of the virtual-database concept. |
