createCombiner: V => C
mergeValue: (C, V) => C
mergeCombiners: (C, C) => C
Map/Reduce-side Aggregator
Aggregator
is a set of functions used to aggregate distributed data sets:
Note
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Aggregator is created in combineByKeyWithClassTag transformations to create ShuffledRDDs and is eventually passed on to ShuffleDependency. It is also used in ExternalSorter.
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updateMetrics
Internal Method
Caution
|
FIXME |
combineValuesByKey
Method
Caution
|
FIXME |
combineCombinersByKey
Method
Caution
|
FIXME |