The identity column helps in generating sequence numbers, keeping uniqueness in place without manual intervention. This is also called a database generated unique primary index, as we are forcing the system to generate a row value for us.
Identity columns save ETL overhead and maintenance by generating unique values if rows are not naturally unique. Identity columns can also help in even data distribution.
DBC.idcol is a dictionary table, and a row is written to it whenever a identity column is created. Following is the DDL of the table:
As we have just created an identity column table, let's check the content of this dictionary ...
