LocalAccumulateBy

Groups records and reduces each group to a single record per group locally on each shard.

public <I extends java.io.Serializable> GearsBuilder<I> localAccumulateBy​(
	gears.operations.ExtractorOperation<T> extractor, 
	gears.operations.AccumulateByOperation<T,​I> accumulator)

The localAccumulateBy function is similar to accumulateBy, except it performs the operation locally on each shard without moving data between shards.

On each shard, it iterates through the records in the pipe, groups them based on the provided extractor, and then reduces each group to a single record per group with the accumulator function.

The initial value of the accumulator is null.

Parameters

Type parameters:

Function parameters:

Returns

Returns a GearsBuilder object with a new template type.

Example

GearsBuilder.CreateGearsBuilder(reader).
   	localAccumulateBy(r->{
   		return r.getStringVal();
   	},(k, a, r)->{
   		Integer ret = null;
   		if(a == null) {
   			ret = 0;
   		}else {
   			ret = (Integer)a;
   		}
   		return ret + 1;
});