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0. Just a reminder for anyone seeing claims that Cloud Spanner beats the CAP theorem:
1. CAP has always said only one thing: that there is always a particular network failure that forces you to give up either C or A.
2. It has nothing at all to do with how likely that failure mode is. The failure is system-specific.
3. The benefit of CAP is that it tells us every system will fail in this way, and so system designers don't chase the impossible.
4. Lots of systems give you consistency and availability up until that failure happens.
5. Think of it this way: CAP tells us that every system has an achilles heel, or Kryptonite, that means giving up C or A for some period.
6. Google has taken their Kryptonite and buried it deep in some black hole somewhere.
7. It still exists, and may come back to haunt them, but the likeihood of doing so is small.
8. That's the benefit that managing their own network, and building in high levels of redundancy, affords them.
