You can literally do version control in the database as well. Upgrade and downgrade your entire scheme at will. Unfortunately the only open source software I'm

You can literally do version control in the database as well. Upgrade and downgrade your entire scheme at will. Unfortunately the only open source software I'm aware of that does this is Archiveopteryx http://archiveopteryx.org/db/mailstore http://archiveopteryx.org/db/mailstore http://archiveopteryx.org/db/schema http://archiveopteryx.org/db/schema