Slowly Changing Dimension type 3

Slowly Changing Dimension type 3

In SCD type 3, a new column is added to the orginal data, which displays the partial historical data

Let us consider the same example that we used in SCD type 1 and SCD type 2


EmpNo      Name       Location
1001             Mark           London

Consider Mark moves from London to Manchester, then a new column is added to the previous data as shown below

EmpNo      Name       CurrentLocation   PreviousLocation

1001             Mark           Manchester               London

Consider Mark moves again from Manchester to Dublin then you have


EmpNo      Name       CurrentLocation   PreviousLocation

1001             Mark           Dublin                       Manchester

So, SCD type 3 maintains partial history

Advantages:
It maintains partial history and with this size of the table doesn't increase as much as it does in SCD type 2



Disadvantages:
The organisation doesn't have complete information the employee as it cannot track the complete history of the employee i.e., from the above example when Mark moves to Dublin the organisation doesn't have any trace of his working in London

Note: SCD type 3 maintains  Current data + partial history