Slowly changing dimensions are dimension tables that have slowly increasing dimension data, as well as updates to existing dimensions. Ex : if a person Mr. x is living in the city C1 has a transaction in a bank and his details is maintained and after some years he moves to city C4, that means he has his new details develped but the bank need to maintain the details i.e both c1 and c2 details ,the history has to be maintained fully or sometimes partially , so in this cases the necessity of SCD is required
When updating existing dimensions, you decide whether to keep all historical dimension data, no historical data, or just the current and previous versions of dimension data.
