The Type 1 Dimension mapping inserts new rows with a new primary key and updates existing rows. When you create a session for the mapping, configure the session as follows:
In the session properties, click the General Options settings on the Properties tab. Set Treat Source Rows As to Data Driven.
In the session properties, click the Target Properties settings on the Mappings tab. To verify that the Integration Service loads rows to the target properly, select Insert and Update as Update for each relational target.