com.rpl.rama.ops

Interface RamaCombinerAgg<T>

Type Parameters:

T - Type of data

All Superinterfaces:

RamaSerializable, java.io.Serializable

public interface RamaCombinerAgg<T>
extends RamaSerializable

Base interface for custom combiner implementations. In a combiner, the start input and aggregated values are of the same form. A combiner executes by aggregating two values at a time until all input has been aggregated to a single value. Because the input and aggregated values are of the same form, combiners can parallelize computation of a single aggregation.

See Also:

Aggregators documentation

Method Summary

Modifier and Type	Method and Description
T	combine(T curr, T arg) Combine two values into an aggregated value
default boolean	isFlushRequired() Controls memory usage when Rama performs two-phase optimization for combiners.
T	zeroVal() Returns result value if there is no input

Method Detail

combine

T combine(T curr,
          T arg)

Combine two values into an aggregated value

Parameters:

curr - First value

arg - Second value

Returns:

Aggregated values

zeroVal

T zeroVal()

Returns result value if there is no input

isFlushRequired

default boolean isFlushRequired()

Controls memory usage when Rama performs two-phase optimization for combiners. Should be overridden to return true if the memory usage of aggregated values grows with each aggregation.

See Also:

Two-phase aggregation documentation