Concept of Data Warehouse

A Data Warehouse is a database that collects, integrates and stores an organization’s data with the aim of producing accurate and timely management information and support data analysis. That is, a kind of special data base designed and maintained with the goal of decision support system of any operational system. Data are collected and copied to the data warehouse so that queries can be performed without disturbing the performance or the stability of the main system or the operation body.

According to Bill Inmon, who is recognized as the “Father of Data Warehouse”, the formal definition of a Data Warehouse is a computer database and its supporting components are:
• Subject oriented, meaning that the data in the database is organized so that all the data elements relating to the same real-world event or object are linked together;
• Time variant, meaning that the changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time;
• Non-volatile, meaning that data in the database is never over-written or deleted, but retained for future reporting; and,
• Integrated, meaning that the database integrates data from most or all from an organization’s operational applications, and this data is kept consistent.
Data warehouses are generally batch updated at the end of the day, week or some period. Its contents are typically historical and static and may also contain numerous summaries.