Data Warehousing Concepts

The original concept of a data warehouse was devised by IBM as the ‘information ware house and presented as a solution for accessing data held in non-relational systems.

The abbreviated of DW is Data warehouse  is a relational database that is designed for query and analysis rather than for transaction processing is collection of data designed to support Management decision making.

 
A single, complete and consistent store of data obtained from a variety of different sources made available to end users in a what they can understand and use in a business context.

It usually contains historical data derived from transaction data, but it can include data from other sources. It separates analysis workload from transaction workload and enables an organization to consolidate data from several sources.

Development of a data warehouse includes development of systems to extract data from operating systems plus installation of a warehouse database system that provides managers flexible access to the data. 

Data warehouse: A subject-oriented, integrated, time-variant, and non-volatile collection warehousing tion of data in support of management’s decision-making process.

Subject-oriented: Integration is closely related to subject orientation. Data warehouses must put data from disparate sources into a consistent format (such as customers, products, and sales) rather than the major application areas (such as customer invoicing, stock control, and product sales)

Integrated : Integration is closely related to subject orientation. Data warehouses must put data from disparate sources into a consistent format. They must resolve such problems as naming conflicts and inconsistencies among units of measure. When they achieve this, they are said to be integrated.

The source data is often inconsistent using, for example (having different formats) because of different source data from different applications systems.

 

Time-variant: The data in the warehouse is only accurate and valid at some point in time or over some time interval

Non-Volatile: The data is not updated in real time but is refreshed from operational systems on a regular basis. New data is always added as a supplement to the database, rather than a replacement