A data warehouse is a relational database that is constructed for analysis and reporting rather than to manage transaction system. Design should be adequate enough to answer business people or management needs from it. So, once design is prepared, it would be good to document it in a way that business people can easily read and understand it to have successful data warehouse environment.
Data Warehouse Bus Matrix is a diagram or tool developed by Kimball group to describe data warehouse design blueprint. It is component or consider as part of data warehouse architecture. It is visual picture of business process and confirmed dimensions. It has no relation with database technology and platform which company is planning to use for ETL.
This step comes when requirement is gathered and to represent technical design of business requirements understanding. It is master document and can be more powerful when comes with great business process knowledge to express ultimate goal of data warehouse.
Below is picture of sample example of bus matrix with horizontal list of dimensions and vertical list fact or business process.
Purpose Of Creating Data Warehouse Bus Matrix:
- It is first level presentation of data marts.
- To explain overall objective of data warehouse to technical professionals and business audience.
- It serves as a technical or management document to communicate with top executives.
- To show mapping between the business processes and detailed dimensions before development phase get started.
Now, let’s understand terms used to create data warehouse bus matrix.
It contains descriptive or detailed textual information of the business. Examples of dimension can be customer, location and product. Dimensions can be categorized as per their nature of storing data. Generally it is limited in terms of number of rows; however it can be wide with large number of columns. Power of data warehouse depends on proportional quality and depth of dimension attributes.
Measures are derived from fact data. We use term fact to represent a business measure. It is actually field/column of fact table on which numeric or aggregate functions can be applied. It is additive or semi-additive in nature. For example measure amount indicating total sales amount for instance in thousand of euros or another measure could be quantity, representing the number of units sold.
Measure group is a group of measures which are related to single business process or facts. For example, sales is a business process while total sales, average sales, monthly sales can consider as measure group.
We believe, for data warehouse architect, it is great tool or document to relate dimension, fact and in the meanwhile providing document to business/field people for understanding of design. The Bus matrix document is also useful for developers to help at the time of developing analysis and reporting services on business requirement.
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