Data Warehouse
As per Bill Inmon "A warehouse is a Historical, subject-oriented, integrated, time-variant and non-volatilecollection of data in support of management's decision making process".
By Historical we mean, the data is continuously collected from sources and loaded in the warehouse. The previously loaded data is not deleted for long period of time. This results in building historical data in the warehouse.By Subject Oriented we mean data grouped into a particular business area instead of the business as a whole.By Integrated we mean, collecting and merging data from various sources. These sources could be disparate in nature.By Time-variant we mean that all data in the data warehouse is identified with a particular time period.By Non-volatile we mean, data that is loaded in the warehouse is based on business transactions in the past, hence it is not expected to change over time.
