Identity columns are columns that have unique values for every row in the table. Because those values confer uniqueness on every row, the system can use the values to identify each row in a table. When a column is defined as an identity column, Vantage automatically generates a unique numeric value for the column in every row added to the table.
Identity columns can be used to generate unique values for UPI, USI, and primary key columns. However, instead of adding identity columns for this purpose, Teradata recommends creating a UPI from a combination of frequently queried columns
For more information about indexes, see Indexes.