A data warehouse is subject-oriented, integrated, time-variant and non-volatile [data] collection in support of management decision making processes.
• Subject-oriented: all relevant data concerning a subject http://www.thearling.com is gathered and stored in a single database.
• Integrated: all data in the warehouse must be compatible with each other regardless of type or location.
• Time-variant: all data contains a reference to time so that the age of each piece of data can be determined.
• Non-volatile: the data does not change once it has been collected.