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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