When missing code / unique identifier in transactual data (general ledger) for list dimension
What is the best way of treating a general ledger, in other words a big data transaction file, that is required to be in the data hub and is missing a unique identifier for each row, i.e. something to be used as a code for the list that will act as the dimension for the DATA module? I could create my own code in the file 1, 2, 3, ... and so on, but when the customer then load in the next month and they cannot start over from 1 but need to follow the count. This seems a bit manual. What would be the best practice here in case the customer will not / cannot provide me with a unique identifier?