Data Marts are nothing but the sub sets of the data warehouse. The information or the data which is inside data mart pertains to single department whereas data warehouse is group of all of them and has all the information regardless of any group.
Ø To speed up the queries by reducing the volume of data to be scanned.
Ø To segment data into different hardware platforms.
Ø To structure data in a form suitable for a user access tool.
Data Mart should be a designed as smaller version of snowflake schema, within the data warehouse and should match the database design of data warehouse.
It helps maintaining control over database instances.
The summary table helps to summarize the data mart in the same way of data warehouse.