This is part 2 of our "Use of Time in Distributed Databases" series. We talk about the use of logical clocks in databases in this post. We consider three different approaches:vector clocksdependency graph maintenanceepoch service In the upcoming posts we will allow in physical clocks for timestamping, so there is no (almost no) physical clocks involved in the systems in part 2.   1. Vector clocksDynamo: Amazon's highly available key-value store (SOSP'07)Dynamo employs sloppy quorums and hinted h...