Use of buffered-sql for logging auth data to db

FR 3.0.12 Is the use of the buffered-sql virtual host just for processing accounting data ? What about radpostauth data ? Just set up the buffered-sql config and I can see that a file called detail.work has been created .... with Accounting packets in it. Is this file supposed to change size as records get processed? currently just using a file called detail and not detail-<timestamp .....> A