Benefits and Drawbacks of data warehousing

benefits that a data warehouse provides are as follows:

A data warehouse provides a common data model for all data of interest regardless of the data's source. This makes it easier to report and analyze information than it would be if multiple data models were used to retrieve information such as sales invoices, order receipts, general ledger charges, etc.

• Prior to loading data into the data warehouse, inconsistencies are identified and resolved. This greatly simplifies reporting and analysis.
• Information in the data warehouse is under the control of data warehouse users so that, even if the source system data is purged over time, the information in the warehouse can be stored safely for extended periods of time.
• Because they are separate from operational systems, data warehouses provide retrieval of data without slowing down operational systems.
• Data warehouses facilitate decision support system applications such as trend reports (e.g., the items with the most sales in a particular area within the last two years), exception reports, and reports that show actual performance versus goals.
• Data warehouses can work in conjunction with and, hence, enhance the value of operational business applications, notably customers relationship management (CRM) system

There are also disadvantages to using a data warehouse. Some of them are:

• Over their life, data warehouses can have high costs. The data warehouse is usually not static. Maintenance costs are high.
• Data warehouses can get outdated relatively quickly. There is a cost of delivering suboptimal information to the organization.
• There is often a fine line between data warehouses and operational systems. Duplicate, expensive functionality may be developed. Or, functionality may be developed in the data warehouse that, in retrospect, should have been developed in the operational systems and vice versa
  

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2. DMReview Magazine Glossary. Data Management Review and SourceMedia, Inc. 2008.
3. R. Kelly Rainer Jr. efraim turban. Introduction to information systems 2nd edition. Asia. John Wiley & Son Inc
4. Data mart. Wikipedia the free encyclopedia. Available at http://en.wikipedia.org/wiki/Data_warehouse