What is a Data Mart ??
A Data Mart is a subset or form of Data Warehouse only but its scope is limited to a particular subject.In other words, It is a specific repository of data that is designed for a specific subject or a specific business function or a set of related business functions ,to answer specific set of questions for a specific set of users.
Source of Data for a Data Mart :
1. Internal Opearational Systems.
3.Data Warehouse systems.
Data Modelling Technique for Data Mart :
Unlike the Data Warehouse which is multidimensional as it is a central repository that contains data for all the departments of the entire organization , A Data Mart is restricted to a particular department or subject , hence it is designed as a one Dimensional Model as Star Schema ( OLAP cube) and is made up of single Fact table and multiple dimension tables.
Top – Down and Bottom – Up Approaches of Data Mart :
Types of Data Marts:
Based on the source of data , Data Marts can be categorized into the following two categories:
1.Independent Data Mart :
In an Independent Data Mart , data comes directly from the Internal operational source systems or external sources.In other words they are not dependent upon they are not dependent upon the Data warehouse for their data input.
2.Dependent Data Mart :
Dependent Data Marts ,On the other hand are dependent upon the Data Warehouse for their data input.
Difference Between Dependent and Independent Data Marts :
|Dependent Data Mart||Independent Data Mart|
|Data comes from Internal or External Source Systems||Data comes from Data Warehouse|
|In Dependent Data Mart , Data does not undergoes all the
three process i.e.Extraction , Transformation and Loading
.The Data is already cleaned and transformed in the Data warehouse ,only the right set of data as per the destination mart is loaded into the Data Mart.
|In Dependent Data Mart , Data undergoes all the three process i.e. Extraction , Transformation and Loading .|
|They are basically designed to improve performance of data warehouse and provide quick accessibility as they contain information for a particular department.||They are designed to provide quick solutions in case business needs to analyze data for departments separately. They are easy to maintain as data is limited.|
Example of Data Mart :
Need of Data Mart :
Limitations of Data Mart :
- Data Marts are limited to a specific area as they are designed to cater the needs of a particular department , hence when it comes to entire organization, they do not serve the purpose.
- They do not support huge database.
Steps for Designing Data Mart:
Difference Between Data Warehouse and Data Mart :
Virtual Data Mart :