Data warehouse concept in DBMS

Data warehouse is also known as enterprise data. Data warehouse was first introduced by Bill Inmon in 1990. An organization needs the historical data for analyzing and reporting. These historical data helps an organization for better decision making about their organization.  Data warehouse contains historical and current data of organization. A data warehouse is subject-oriented, integrated, time variant and non-volatile collection of data. Large organizations have complex internal structure and their data is stored in different locations. For example, customer data and product data may be stored on different locations. But a corporate decision maker requires access of all these data at one place. Data warehouse is a solution of this problem.

Subject-oriented:  Subject-oriented means providing information about only subject rather than the other topic. For an organization subject can be products, sales, revenue and so on.

Integrated: A data warehouse contains data from mixed or heterogeneous sources.

Time-variant: A data warehouse is time variant because a particular data in data warehouse is valid at particular time.

Non-volatile: A data warehouse is kept separate from on-going operation database. In data warehouse previous data is not deleted when new data is added to data warehouse.

Advantages of Data Warehouse

• Helps decision making for an organization
• Cost effective decision making
• Customer services enhances
• Customer relationship enhances
• Gives competitive advantages

Disadvantages of Data Warehouse

• Implementation of data warehouse is very costly
• High maintenance is required
• Time consuming
• Hidden problems

Characteristics of Data Warehouse

• Multidimensional conceptual view
• Generic dimensionality
• Multiuser support
• Flexible reporting
• Accessibility of data from different sources
• Initiative data manipulation
• Consistent reporting performance