Data Warehouse

DWH focuses on enterprise data across many subject areas

It stores large volume of data and maintains historical information.

• A datawarehouse is a very large data base  (VLDB) 
• Has more Subject-Oriented Areas
• A DW is a database designed to support a broad range of decision tasks in a specific organization
• Size is > 100 GB  
• Running adhoc(unplanned) queries from a huge DW takes long time 

Data Mart

DM are restricted to a single or particular subject area.  Set of data marts are equal to Data warehouse.

It stores smalla amount of data and maintains aggregated data.

• A data mart is for smaller databases
• Has Less Subject-Oriented Areas
• A DM is a selected part of the DW which supports specific decision support application requirements of a company’s department
• Size is < 100 GB
• Running adhoc quries in DM allow the efficient exection of predicted queries