Data Mart Defined

A data mart is a subject-orientated database which is a subset of a data warehouse. Data marts contain repositories of summarized data collected for analysis, on a specific section or unit within an organization such as sales, finance or marketing.  The primary purpose of a data mart is to isolate a smaller set of data from a whole to provide easier data access for the end users.

Businesses can take 2 directions in establishing a data mart:

1. Create a data mart within an already established data warehouse.
2. Create an independent data mart from source data and then create a data warehouse around it.

There are three different type of data marts:

1. Dependent Data Marts – are created from an existing enterprise data warehouse. It can be a logical view or physical subset of the data warehouse:
   • Logical view – A virtual table/view that is logically—but not physically—separated from the data warehouse
   • Physical subset – Data extract that is a physically separate database from the data warehouse
2. Independent Data Marts – are a stand-alone system—created without the use of a data warehouse—that focuses on one subject area or business function. Data is extracted from internal or external data sources, processed, then loaded to the data mart repository where it is stored.
3. Hybrid Data Marts – combine data from an existing data warehouse and other operational source systems. 

Advantages of using a data mart include:

• Improving end-user response time by allowing users to have access to the specific type of data they need
• A condensed and more focused version of a data warehouse
• Lower cost than implementing a full data warehouse
• Holds detailed information
• Contains only essential business information
• Data is less cluttered
• Works to integrate all data sources

In Data Defined, we help make the complex world of data more accessible by explaining some of the most complex aspects of the field.

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