I wonder if this means that an evil entity could cause massive data loss by broadcasting fake GPS clock information, which would mess around with the decisions that these databases make regarding consistency. That would be terrifying.
The spanner paper doesn't discuss this in detail, but they have atomic clocks in addition to GPS clocks in large part because GPS clocks can fail or be expoited in this way and atomic clocks cannot.
Re:Reading Lamport, again
by justicezyx on Thursday June 26, 2014 @08:37PM
(#7952254)
Spanner has "interval" in its time. It uses high-accuracy atomic clocks to narrow the uncertainty window. It actually proves that Lamport's technique is more fundamental, because even with such hardware, you still can run into situation where the system has no idea what the order of events is.
My tentative conclusion was that the giant difference between 1978 when the Lamport clocks paper was published, and 2012, is access to GPS. The fact that we get to take advantage of a DoD-built fleet of dozens of satellites that are constantly broadcasting extremely accurate times is pretty extravagant. Google can build systems today that rely on clocks in data-centers thousands of miles apart both being very close to "absolute" time, with explicit, conservative bounds on their error, in part through heavy use of GPS clocks. But for most of us that don't have an elaborate system of fancy clocks in our data-centers, Lamport's approach of having machines update one another's clocks (be they logical or physical) as they exchange messages is still a lot more relevant.