Rules and Guidelines for Identity Columns

The data type for an identity column must be either int or bigint.
When you create a mapping for an insert operation, you must link either all the source and target identity columns or none.
When you create a mapping for an update, upsert or delete operation, you cannot map the identity columns that are not part of the primary key.
If an identity column is part of the primary key, you must map the column for update, upsert, and delete operations, or the
session
fails. However, you cannot set a source value for these columns.
The ExplicitID and MaxError count options are removed for the upsert, update, and delete operations.