What is Data Warehouse???

A data warehouse is essentially a set of hardware and software components that are used to analyze in a more effective manner, the massive amount of data that an organization has accumulated, and thereby facilitate sound business decisions.

In other words, a Data Warehouse is a repository of integrated data, available for queries and analysis. Data in a Data Warehouse is extracted from heterogeneous sources as and when it is generated. This makes it much easier and more efficient to run queries over data that originally came from different sources.

Data Warehousing is a method of extracting useful information from on-line / off-line databases for the purpose of decision support and analysis. It is a subject-oriented, integrated, time-variant and non-volatile collection of data managed in support of decision-making process. It is a repository of consistent historical data that can be easily accessed and manipulated for decision support.

Creation of a Data Warehouse would be useful for:

• IT or business professionals, who spend a lot of time developing special reports for decision makers.
• Assimilating data which is otherwise scattered on different systems, in different departments about which a user might be unaware.
• Decision makers, who require timely meaningful information