User:Leekinboo/Fast changing dimensions

== Fast changing dimensions


 * What are fast changing dimensions?

Fast changing dimensions are also called rapidly changing dimensions.

The best approach for handling very fast changing dimensions is to separate the fast changing attributes into one or more separate dimensions which are called mini-dimensions. The fact table then has two or more foreign keys—one for the primary dimension table and another for the one or more mini-dimensions (consisting of fast changing attributes). The primary dimension table and all its mini-dimensions are associated with one another every time we insert a row in the fact table. To handle fast changing dimensions, here are the activities: 1.All dimensions are analyzed to find which dimensions change very fast. 2.Assume that the Customer Dimension is a fast changing dimension. 3.The Customer dimension is analyzed further to understand the impact on the size of the dimension table 4.The next step is to analyze the fast changing Customer dimension in detail to  identify which attributes of this dimension are subject to change fast. Assume that we identify seven fast changing attributes in the Customer dimension.They are age, income, test score, rating, credit history score, customer account status, and weight. Such fast changing attributes are then separated into one new dimension 5.After having identified the constantly changing attributes and putting them in  the Customer_Mini_Dimension mini-dimension table, the next step is to   convert these identified attributes individually into band ranges. The concept behind this exercise is to force these attributes to take limited, discreet values.
 * Identify fast changing dimensions

Open questions and challenge
Any other method to organize the fast dimension? What the disadvantage to have the fast dimensions in a mini-dimension?