Good Morning ,
Kimball writes:
Type 2: Add New Row
Slowly changing dimension type 2 changes add a new row in the dimension with the updated attribute values. This requires generalizing the primary key of the dimension beyond the natural or durable key because there will potentially be multiple rows describing each member. When a new row is created for a dimension member, a new primary surrogate key is assigned and used as a foreign key in all fact tables from the moment of the update until a subsequent change creates a new dimension key and updated dimension row. A minimum of three additional columns should be added to the dimension row with type 2 changes: 1) row effective date or date/time stamp; 2) row expiration date or date/time stamp; and 3) current row indicator.
After Initial load is completed, we identify the changed or new record in the source system and update the target system with the changed record. Identifying and loading only changed data is called Change Data Capturing. This type of load is used to maintain the history data in the target system (SCD Type 2).
There are two CDC methods - Source based CDC and Target based CDC.
Source-based CDC evaluates the source table to determine, what record has changed and extracts only changed records to load into target tables.
Target-based CDC extracts all the data from the source, compares the source and target rows using table comparison and then loads only the changed rows into the target system.
My question is:
A Dimension "Usuarios" SCD Type 2 is going to be loaded after Initial load using Target-based CDC .
Must I added this three additional columns 1) row effective date or date/time stamp; , 2) row expiration date or date/time stamp; 3) current row indicator. to the Dimension "Usuarios" ?
Or this three additional columns must be added to the Dimension "Usuarios" only when the CDC method is Source based CDC is it right ?
Thanks in advance.
Best Regards.
Antonio