Top Highlights

• tradeoff. Concurrent programming involves a fundamental tradeoff between safety (avoiding errors such as update conflicts) and liveness (responding quickly to clients).
• Using a single node as the target for all writes for some data makes it much easier to maintain update consistency.
• Consistency guarantees aren’t something that’s global to an application. You can usually specify the level of consistency you want with individual requests. This allows you to use weak consistency most of the time when it isn’t an issue, but request strong consistency when it is.
• The map-reduce approach is a way of thinking about concurrent processing that trades off flexibility in how you structure your computation for a relatively straightforward model for parallelizing the computation over a cluster. Since it’s a tradeoff, there are constraints on what you can do in your calculations. Within a map task, you can only oper...
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