What is a data mart?
A data mart is best regarded as a subset of a data warehouse. Oftentimes its use is oriented towards one specific business unit. They are useful to store summarized data, easily accessible to business users within that specific business unit.
A data mart has several benefits:
- Faster response time due to the lower volume of data.
- Provides access to often requested aggregated statistics.
- There should only be one subject matter expert, drastically reducing organizational complexity.
There are some drawbacks, however. The main one is that the maintenance of a multitude of data marts can be cumbersome and time-consuming.
Both IBM and Talend have a good introductory piece on data marts, here and here.