What is a Data Warehouse
The description of what a data warehouse is varies greatly. The definition that I give that seems to work is that a data warehouse a database repository that supports system interfaces, reporting and business analysis, data integration and domain normalization, and structure optimization. The structure can vary greatly depending the school of thought used to construct the data warehouse and will have at least one data mart.
What a data warehouse is:
- A source of data and enriched information used for reporting and business analysis.
- A repository of metadata that organizes data into hierarchies used in reporting and analysis
What a data warehouse is not:
- A reporting application in and of itself; it is used by other applications to provide reporting and analysis.
- An exact copy of all tables/data in the source systems. Only those portions of source system tables/data required to support reporting and analysis are moved into data warehouse.
- An Online Transaction Processing (OLTP) system.
- An archiving tool. Data is kept in data warehouse in accordance with the data retention guidelines and/or as long as need to support frequently used reporting and analysis needs.