Building the Data Warehouse

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data warehouse

meta data










Figure 5.11 The data warehouse contains data over a long period of time and must manage multiple structures/definitions of data. The operational environment assumes that there is only a single correct definition of data at any one time.

Contrast the notion that there will be many structures of data over time in the data warehouse environment with the meta data found in the operational environment. In the operational environment it is assumed that at any one moment, there is one and only one correct definition of the structure of data.

Context and Content

In the past, classical operational information systems have focused their attention on the very current data of a corporation. In the operational world, the emphasis is on how much an account balance is, right now or how much is in inventory, right now or what the status of a shipment is, right now. Of course, every organization needs to know about current information. But there is real value in looking at information over time, as is possible with data warehousing. For example, trends become apparent that simply are not observable when looking at current information. One of the most important defining characteristics of the data warehouse is this ability to store, manage, and access data over time.

With the lengthy spectrum of time that is part of a data warehouse comes a new dimension of data-context. To explain the importance of contextual information, an example is in order.

Скачать в pdf «Building the Data Warehouse»