Data warehouse

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May 18, 2014 by Ozgur Ozden

Data warehouse (DW): A very popular definition is made by Inmon (1992) as “A data warehouse is a subject-oriented, integrated, time-variant, nonvolatile collection of data in support of management’s decision-making process.” It is a central database where data collected from multiple sources in the business and used to make critical or strategic decisions about the company. DW can store historical data about the business, yearly, quarterly or monthly or actual current live data. This data is usually gathered from the other sources in the company such as Sales, Marketing, Accounting, HR departments and so on. At this point in order to feed these data collected from the various sources into the data warehouse we need a data Extract, Transform and Load (ETL) tool.


There are many advantages and benefits of using a data warehouse.
1- Since the data is specifically extracted, loaded and clustered according and inconsistencies are removed so data is pure and clean.
2- Multiple type of data can be indexed
3- Since data warehouse is separated from the actual system, it maintained data feed without really interfering with the real system.
4- Supports forecasting and decision making process by providing various reports.
5- Better customer service can be provided.

Today data warehouses are the most used and trusted system to forecast, analyze and manage the trends in the business. In the mean time support and maintenance is extremely important to get reliable reports from the system. Such an data extraction, management, data loading, transform and queries should be done by qualified team of people.

Data Mart: can be considered as a data collected from various sources to provide information to a specific purpose. In a sense, data mart is a sub-group of data warehouse contains information about a department, particular group of people or can be served to a certain business segment. It is a small slice of data warehouse where data warehouse provides more enterprise wide information. Each data mart can provide specific information about the business. Since data marts are subject specific, this increases the response time for the end user

1- Wnez (n.d) Data Warehousing (Online) Available at: [Accessed at: 26.10.2013]
2- Project Management within a data warehouse (2009) (online) Available at: [Accessed at: 26.10.2013]


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