That actually makes a lot more sense than my dumb idea .... And seems to be the way to go.
Yes, I keep a "update number" field on each record, which is essential to track which records changed since the last check (you could have a "changed" bit instead, which is reset on sync -- but that makes sync much more limited, e.g. you can't sync to more then one other destination). P.S: The book example in chapter 6 for database synchronization has the problem I pointed to above -- it should switch to .utcnow when it is added, and/or there should be a discussion of the daylight saving time change and/or multiple time zone problems.
