How does Sync Services track changes?
Sync Services uses an Anchor based model. Each time a sync operation occurs it gets a reference mark from the server. It could be the servers DateTime, or a TimeStamp (RowVersion). The client saves that value for the next sync operation. Each time the client synchronizes a particular SyncGroup, it first requests the server anchor. It than executes the queries on the server using the last anchor as the low range, and the new anchor as the high range. This gets a consistent set of changes across several queries. In future releases of the Microsoft Synchronization Platform we’ll be supporting a knowledge based sync model as well as the anchor based model discussed here.
