Slowly changing dimensions (SCD) are used to capture changing data within the dimension over time. How could we track the changes in the example below?
Types of SCD
Type 1 - Overwrite
Replace all existing data
Lose historical data
Often used for data corrections
Type 2 - Add historical columns
To analyse historical data, you will need to understand when the customer was from Corporate and Retail.
Creates additional records on each changing record event
History of dimension changes are kept
Expensive database operation
Adds a surrogate key
Surrogate key
Sequentially generated unique number
Eliminate source system dependency
Increase performance with using suitable data type on joins
