The CAP Theorem is an important foundation for understanding distributed systems. Summarizing all the available literature on CAP and some modern interpretations of the theorem theorem, we know that any distributed system must decide when dealing with latency or network failure whether it will choose Consistency or Availability.
Consistency - The result of a read at T1 is the same as T2 if there were no writes between T1 and T2. Basically, any read can see any previously completed write.
- Availability - The system is Partition Tolerance - The system is able to maintain its guarantees If a network failure prevents communication between some nodes, the system
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Wikipedia defines Consistency as all nodes see the same data at the same time, but that is incorrect because the CAP Theorem is defined in terms of the observed rather than actual state of the system. |
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