Chapter 2. The Data Warehouse Environment
The data warehouse is the heart of the architected environment, and is the foundation of all DSS processing. The job of the DSS analyst in the data warehouse environment is immeasurably easier than the job of the analyst in the classical legacy environment because there is a single integrated source of data to draw from (the data warehouse), because the granular data in the data warehouse is easily accessible, and because the data warehouse forms a foundation for reusability and reconciliation of data.
This chapter describes some of the more important aspects of the data warehouse. A data warehouse is a subject-oriented, integrated, nonvolatile, and time-variant collection of data in support of management's decisions. The data warehouse contains granular corporate data. Data in the data warehouse is able to be used for many different purposes, including sitting and waiting for future requirements which are unknown today.
The subject orientation of the data warehouse is shown in Figure 2-1. Classical operations systems are organized around the functional applications of the company. For an insurance company, the applications may be for the processing of auto, life, health, and casualty. The major subject areas of the insurance corporation might be customer, policy, premium, and claim. For a manufacturer, the major subject areas might be product, order, vendor, bill of material, and raw goods. For a retailer, the major subject areas may be product, ...