A data mart is the access layer of a data warehouse that is used to provide users with data. Data marts are often seen as small slices of the data warehouse. Data warehouses typically house enterprise-wide data, and information stored in a data mart usually belongs to a specific department or team.
The key objective for data marts is to provide the business user with the data that is most relevant, in the shortest possible amount of time. This allows users to develop and follow a train of thought, without needing to wait long periods for queries to complete. Data marts are designed to meet the demands of a specific group and have a comparatively narrow subject area. However, narrow in focus doesn’t necessarily mean small in size. Data marts may contain millions of records and require gigabytes of storage.
Advantages of using a data mart:
- Improves 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
- Each is dedicated to a specific unit or function
- Lower cost than implementing a full data warehouse
- Holds detailed information
- Contains only essential business information and data and is less cluttered
- Works to integrate all data sources
The creation and use of a data mart leads to a great summarization of data. A much broader range of data is available with data warehouses; however, this data is generally not summarized, can make it difficult to sort through masses of data, and increases query times.