Tuesday 19 March 2013

Implementing Slowly Changing Dimensions (SCD) Type 3 using Talend

In the previous post, I had shown you, How to implement SCD Type 1 and SCD Type 2. Today, I am going to implement SCD Type 3.

In SCD type 3, we only store the prior/previous value of the dimension attribute. We do not keep all the historical changes for the dimension attribute. Hence we need to have a additional column in the dimension table which will hold the prior or previous value.

Summary of Slowly Changing Dimension Type 3
 
1. Only Prior/Previous value is stored. Not all the historical changes for the dimension attribute.
2. New column need to be created which holds the prior value.
3. As no new record for the change in the Dimension attribute is added, Surrogate Key remains the same.


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