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Unformatted text preview: h any other CPU’s read. But if nothing changes for long enough, all CPU’s see the same value of memory. Examples: NFS, DNS, web. Why not always do sequential consistency or linearizability? We’ll see that it simplifies the implementation tremendously to provide only eventual consistency, especially when there is replicated or sharded data. Then you don’t need to instantly propagate every update to every replica – you can do that in the background. Another reason: if nodes can become disconnected, or we want to provide access to data even when the most up to date copy is unavailable. (some would say that need to use eventual consistency for any highly available system.) For example, Amazon’s revenue is $100K/minute, and customer purchase rates decline dramatically even for small increases in client response time. So for many sites, it is important for it to be always up and responsive, even if data is not always consistent. Would initial program work with eventual consistency? Could you modify program so that it would wor...
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This document was uploaded on 04/04/2014.
- Spring '14