A Data Warehouse is computer database that collects and store data in a form to produce correct and timely information with an aim to support data analysis.
Data Warehouse; you can imagine are like a well structured goods store.
These databases are developed to handle large volume of information in an intelligent manner, to provide information as well as analysis together.
The users of Data Warehouse are banks, telecom organization where large volume of data is generated every day.
The data Warehouse is centralized storage of data collected from different sources.
The data Warehouse has emerged from various stages of developments over the years and these are:
§ Offline Operational Database: This was a simple copy of operational database to an off-line server, to support reporting and analysis without impacting performance of operational databases.
§ Offline Data Warehouse: Data Warehouses at this stage were periodically updated from operational databases automatically to support reporting and analysis.
§ Real Time Data Warehouse: Data Warehouses at this stage are updated on a transaction basis from an operational database and provide reporting and analysis based on always updated information.
§ Integrated Data Warehouse: This stage is an enhancement of real time data warehouse, in this stage the analysis information of data warehouse is passed back to operational database, which can be used as daily activity of organization for efficient working.
Understanding of Data Warehouse:
§ A data warehouse is a database, which is kept separate from the organization’s operational database.
§ There is no frequent updating done in a data warehouse.
§ It possesses consolidated historical data, which helps the organization to analyze its business.
§ Data warehouse systems help in the integration of diversity of application systems.
Features of Data Warehouse:
§ A data warehouse is subject oriented because it provides information around a subject rather than the organization’s ongoing operations.
§ These subjects can be product, customers, suppliers, sales, revenue, etc.
§ A data warehouse does not focus on the ongoing operations; rather it focuses on modelling and analysis of data for decision making.
§ A data warehouse is constructed by integrating data from heterogeneous sources such as relational databases, flat files, etc.
§ This integration enhances the effective analysis of data.
§ The data collected in a data warehouse is identified with a particular time period.
§ The data in a data warehouse provides information from the historical point of view.
§ Non-volatile means the previous data is not erased when new data is added to it.
§ A data warehouse is kept separate from the operational database and therefore a frequent change in operational database is not reflected in the data warehouse.