The Integration Service generates a current flag of 1 for each row written to the target. This flag indicates the dimension is new or newly updated. If the row is an update to an existing dimension, the Integration Service resets the existing dimension current flag to 0.
As a result, all current versions of a dimension appear in the target with a current flag of 1. All previous versions have a current flag of 0.
For example, the following dimension data is current because the current flag is set to 1:
When these dimensions change, the Integration Service inserts the updated versions with the current flag of 1. The Integration Service also updates the existing rows in the target. It finds the previous current version (where the current flag is set to 1 and updates the current flag to 0: