'Freezing' a database

Does anyone have any suggestions on how to 'freeze' (i.e., save a copy of) the data in a database at a particular point in time? To clarify: In a software development environment, software and its supporting/associated database will develop incrementally. It's fairly easy to 'capture' the state of the software at any one time through tools like RCS. But I am unaware of any RDBMS tools which permit a DBA to capture the database and its data exactly as it stands at a particular moment in time. Would this involve saving complete copies of all tables in the DB as they were at the desired moment? Or are there DB tools in existence which are 'smarter' -- i.e., that can store only the differences between the current DB and the earlier state which needs to be remembered? Please respond via e-mail to: marra@cadswes.colorado.edu Thanks, carol