Snapshotting and log replay should be fairly straightforward, if you save all sql statements in their entirety. Snapshots would stop the world, which might pose a problem, but I presume this is no different to other event sourcing solutions. Given the concurrency of a db, I'm also not sure that there's a strict ordering of all incoming statements.

Edit: Seems like at least Oracle is already doing this: http://en.wikipedia.org/wiki/Redo_log