Use the Retain transformation to copy one or more input table columns to the output table, optionally giving them new names and types in the output table.
The function automatically retains the primary index columns of the input table. You do not have to specify them. However, if the primary key columns are not the primary index columns, you must provide the primary key columns to the output table to uniquely identify each output row, by retaining them or another means.
You can apply the Retain transformation to columns of any data type.