What is Data Warehousing?
In 1993, the ¡§father of data warehousing¡¨, Bill Inmon, [Building the Data Warehouse] gave this definition of a data warehouse. A data warehouse is a subject oriented, integrated, time-variant, non-volatile collection of data in support of management decisions.
„h Subject-oriented means that all relevant data about a subject is gathered and stored as a single set in a useful format;
„h Integrated refers to data being stored in a globally accepted fashion with consistent naming conventions, measurements, encoding structures, and physical attributes, even when the underlying operational systems store the data differently;
„h Non-volatile means the data warehouse is read-only: data is loaded into the data warehouse and accessed there;
„h Time-variant data represents long-term data--from five to ten years as opposed to the 30 to 60 days time periods of operational data.
Data warehousing is a concept. It is a set of hardware and software components that can be used to better analyse the massive amounts of data that companies are accumulating to make better business decisions. Data Warehousing is not just data in the data warehouse, but also the architecture and tools to collect, query, analyse and present information.
