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What Is Combiner Aggregator?

Answer»

A Combiner Aggregator is used to combine a SET of TUPLES into a single FIELD. It has the following signature:

public interface CombinerAggregator {
 T init (TridentTuple tuple);
 T combine(T val1, T val2);
 T zero();
 }

Storm calls the init() METHOD with each tuple, and then repeatedly calls the combine()method until the partition is processed. The VALUES passed into the combine() method are partial aggregations, the result of combining the values returned by calls to init().

A Combiner Aggregator is used to combine a set of tuples into a single field. It has the following signature:

public interface CombinerAggregator {
 T init (TridentTuple tuple);
 T combine(T val1, T val2);
 T zero();
 }

Storm calls the init() method with each tuple, and then repeatedly calls the combine()method until the partition is processed. The values passed into the combine() method are partial aggregations, the result of combining the values returned by calls to init().


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