A data warehouse is a business organization's corporate memory or the main repository of historical data and it typically contains all the raw materials from the decision support system of the management.
The data from the data warehouse are being used by the business intelligence system as on of the main bases for company decisions and that the critical factors that leads to the use of a data warehouse is that the company's data analysts can perform several queries and analysis varying degrees of analysis such as data mining on the data and other related information without affecting negatively or slowing down the operational system.
Given the tremendous requirements for a data warehouse, some IT professionals recommend breaking down the huge data warehouse into data mini marts.
A data mini-mart is actually small (mini) and specialized version of data warehouse and as such, a mini-mart can actually contain a snapshot of operational data which are very useful for business people so that they can strategize based on data analysis of past trends, patterns and experiences.
The main difference between a full blown and big data warehouse and a mini mart is that the creation of the mini mart is predicated on a predefined and specific need for a certain configuration and grouping of select data and such configuration tries to give emphasis on easy access for relevant data and information.
In a business organization implementing a data warehouse, there may be many data mini marts and each one is relevant to one or more business units that the mini mart has been designed to serve.
In a business organization's data warehouse, the mini marts may or may not be related or dependent on each other. In cases where the mini marts are designed with the use of conformed facts and dimensions, then they will be related to each other.
In some data warehousing implementations, each business unit or departmental division is assigned as the owner of its mini mart and this ownership includes taking care of the hardware, software and the data itself.
Implementing mini marts in a data warehouse has tremendous benefits. One of the biggest benefits is the modularization of the entire big system. In the ownership scenario, the data and the physical as well as software infrastructure will be better controlled because it would be easy to pinpoint responsible people or business unit.
With mini marts, each department can use, manipulate and develop as well as maintain their data in any way that they see fit and without having to alter the information inside the other department's mini marts or the data warehouse.
Other benefits associate with implementing mini marts include getting very easy and fast access to data which are frequently needed. If there was no mini mart, a data consumer would have to go through the vast repository inside a central data warehouse and with high volumes of data involved, querying may take a very long time and may even slow the entire system.
Having mini marts can also create a collective view by a group of users and this view can be a good way to know how the company is performing on business unit level as well as in its entirety. Because a mini mart is obviously smaller than an entire data warehouse, response time would be greatly improved while creation and manipulation of new data would be very easy and fast as well.