In a Type 2 Dimension/Version Data mapping, the Integration Service generates a new primary key value for each new dimension it inserts into the target. An Expression transformation increments key values by 1,000 for new dimensions.
When updating a dimension, the Integration Service increments the existing primary key by 1.
For example, the Integration Service inserts the following new row with a key value of 65,000 since this is the sixty-fifth dimension in the table.
The next time you run the workflow containing the session, the same item has a different number of styles. The Integration Service creates a new row with updated style information and increases the existing key by 1 to create a new key of 65,001. Both rows exist in the target, but the row with the higher key version contains current dimension data.
When you run the workflow again, the Integration Service again increments the key. The highest key version contains current dimension data. The target keeps a full history of the item and the order in which the versions occurred.