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Window Function

在处理 流数据 时,为了能在源源不断的数据流上执行聚合计算,将数据 按不同规则切分为一个个“窗口”。



不同滑动窗口对比见下图 [1]


In applications that process real-time events, it is common to perform some set-based computation (aggregation) or other operations over subsets of events that fall within some period of time.[2]

Database System Concepts

One way to deal with the unbounded nature of streams is to define windows on the streams, where each window contains tuples with a certain timestamp range or a certain number of tuples.[3]

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  3. Abraham Silberschatz, Henry F. Korth, and S. Sudarshan, Database System Concepts, Seventh edition (New York, NY: McGraw-Hill, 2020). P502 ↩︎