Thursday, 13 September 2012

SCD Type 1,Slowly Changing Dimension Use,Example,Advantage,Disadvantage

In Type 1 Slowly Changing Dimension, the new information simply overwrites the original information. In other words, no history is kept.
In our example, recall we originally have the following table:

Customer Key
Name
State
1001
Williams
New York

After Williams moved from New York to Los Angeles, the new information replaces the new record, and we have the following table:

Customer Key
Name
State
1001
Williams
Los Angeles

Advantages
  • This is the easiest way to handle the Slowly Changing Dimension problem, since there is no need to keep track of the old information.
Disadvantages
  • All history is lost. By applying this methodology, it is not possible to trace back in history. For example, in this case, the company would not be able to know that Williams lived in New York before.
Usage
About 50% of the time.

When to use Type 1
Type 1 slowly changing dimension should be used when it is not necessary for the data warehouse to keep track of historical changes.

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