As of Cascading 2.2, the FirstNBuffer Buffer is provided as an optimized means to determine the top N elements in a grouping.
The
cascading.operation.buffer.FirstNBuffer
Buffer returns the first N tuples seen in
a given grouping. Unlike the
cascading.pipe.assembly.FirstBy
AggregateBy and
cascading.operation.aggregator.First
Aggregator,
FirstNBuffer will stop iterating the
available tuples when the top N condition is met.
FirstNBuffer is used by
cascading.pipe.assembly.Unique.
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