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It seems to me more like they have "solved" (or broken) the CAP theorem ... http://en.wikipedia.org/wiki/CAP_theorem http://en.wikipedia.org/wiki/CAP_theorem *
by damian2000 14y ago
It seems to me more like they have "solved" (or broken) the CAP theorem ... http://en.wikipedia.org/wiki/CAP_theorem http://en.wikipedia.org/wiki/CAP_theorem
* Consistency (all nodes see the same data at the same time)
* Availability (a guarantee that every request receives a response about whether it was successful or failed)
* Partition tolerance (the system continues to operate despite arbitrary message loss or failure of part of the system)
According to the theorem, a distributed system can satisfy any two of these guarantees at the same time, but not all three.
- snewman 14y agoNo, they haven't broken the CAP theorem. If the network were to partition badly enough, Spanner would lose its quorum and would become unavailable, at least for guaranteed-consistent operations. In practice, a network partition bad enough to bring down something like Spanner is pretty rare. (I worked at Google for four years, and I can't recall such a partition occurring.) But in theory it's certainly possible.
- shin_lao 14y agoThe CAP theorem states that at one point in time you can only have two in three. It doesn't say much more than the obvious. Obviously, if one node parts, you're either inconsistent or available.
- Dave_Rosenthal 14y agoJust to clarify what the CAP theorem says: If one node parts, then that node is either inconsistent or not available. A fault-tolerant database could potentially stay up with a single unavailable node.