What’s C, A and P? Consistency is the easiest one. It roughly means that the clients get the same view of data. By saying that a system is consistent we often mean strong consistency, but it also can come in different flavors. Availability is a property saying that every request to a non-failing node will return a (meaningful) response. The response may not contain all data (so the harvest will not be 100%), but it should be useful for the client. Partition tolerance means that the system will continue working even if any number of messages sent between nodes is lost. This can be e.g. a network failure between two data centers, where nodes in each data center form a partition. Also note that a failure of any number of nodes forms a partition (it is not possible to distinguish between a network failure and a node failing and stopping to respond to messages). The basic statement of the CAP theorem is that, given the three properties of Consistency, Availability, and Pa...
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