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.