> Since you have to account for network partitions, you have to choose between consistency and availability if and when a partition occurs. In other words, the

> Since you have to account for network partitions, you have to choose between consistency and availability if and when a partition occurs. In other words, the CAP divides the world into CP and AP systems. No, it's two out of three. CA systems don't use a network. Consider a database and a work queue which communicates with the database, where they run on the same server. You can achieve consistency and availability in such a system, but only by eliminating partitioning, and there's only the one way to do that: don't run the systems on a network. Nor is this an unrealistic architecture! Far from it, it is in fact the one you should choose if you need both consistency and availability. The parts of the article about the CAP theorem and its consequences are on fairly solid ground as I see it. But the observation about the CAP conjecture is bootless, the conjecture that CAP is "pick two" holds up to scrutiny. Not that it proves the conjecture, just that all three of the "pick two" options describe meaningful systems.