What Is a Data Warehouse?
Definition: A data warehouse is the data repository of an enterprise. It is generally used for research and decision support.
By comparison: an OLTP (on-line transaction processor) or operational system is used to deal with the everyday running of one aspect of an enterprise.
OLTP systems are usually designed independently of each other and it is difficult for them to share information
Why Do We Need Data Warehouses?
1.Consolidation of information resources
2.Improved query performance
3.Separate research and decision support functions from the operational systems
4.Foundation for data mining, data visualization, advanced reporting and OLAP tools
What Is a Data Warehouse Used for?
Making consolidated reports
Finding relationships and correlations
Banks identifying credit risks
Insurance companies searching for fraud