versioning solves this problem. in practice, you have to support retroactive changes, so you have to have "middle" values for versions (i.e. 1.1 between 1 and

versioning solves this problem. in practice, you have to support retroactive changes, so you have to have "middle" values for versions (i.e. 1.1 between 1 and 2). People are usually interested in the timestamps associated with those versions (for which period of time is this version valid, when was this version created), so in practice it's easier to just keep track of the timestamps, and leave the versions implicit.