Wednesday, August 1, 2012

What is Data Warehouse

There are various definitions of Data Warehouse. The most popular definition from Bill Inmon is A data warehouse is a “subject-oriented, integrated, timevariant and nonvolatile” collection of data in support of management’s decision-making process.

Subject-Oriented – This can be used to analyze a particular area.
Integrated – This can be used to integrated data from multiple sources.
Time-Variant – Keeps Historical data in data warehouse.
Non-Volatile – Once data keeps in data warehouse, it will not change. Historical data will never be modified.

A Data Warehouse is a copy of transactional data used to perform analysis and reports.
ERP – It will run the business
BI – Used for reports, data mining and analysis based on historical information.
Data warehousing is a process of managing data from various sources to analyze and generate reports based
on business requirements.
What is MSBI – Microsoft 2005 has built in components to implement data warehouse. The pack contains

Data Warehouse Terminology
OLTP – Online Transaction Processing
OLAP – Online Analytical Processing
Facts – Transaction Tables
Slowly Changing Dimensions
Dimensions – De normalized master tables
Attributes – Columns of Dimensions
Cube – Multi Dimensional storage of data
MOLAP – Multidimensional OLAP
ROLAP – Relational OLAP
Data Mart – Collection of data for a particular subject

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