org.apache.flink.streaming.api.functions.aggregation

Class ComparableAggregator<T>

java.lang.Object

org.apache.flink.streaming.api.functions.aggregation.AggregationFunction<T>

org.apache.flink.streaming.api.functions.aggregation.ComparableAggregator<T>

All Implemented Interfaces:

Serializable, Function, ReduceFunction<T>

@Internal
public class ComparableAggregator<T>
extends AggregationFunction<T>

An AggregationFunction that computes values based on comparisons of Comparables.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.functions.aggregation.AggregationFunction

AggregationFunction.AggregationType

Constructor Summary

Constructors

Constructor and Description
ComparableAggregator(int positionToAggregate, TypeInformation<T> typeInfo, AggregationFunction.AggregationType aggregationType, boolean first, ExecutionConfig config)
ComparableAggregator(int positionToAggregate, TypeInformation<T> typeInfo, AggregationFunction.AggregationType aggregationType, ExecutionConfig config)
ComparableAggregator(String field, TypeInformation<T> typeInfo, AggregationFunction.AggregationType aggregationType, boolean first, ExecutionConfig config)

Method Summary

Modifier and Type	Method and Description
T	reduce(T value1, T value2) The core method of ReduceFunction, combining two values into one value of the same type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ComparableAggregator

public ComparableAggregator(int positionToAggregate,
                            TypeInformation<T> typeInfo,
                            AggregationFunction.AggregationType aggregationType,
                            ExecutionConfig config)

ComparableAggregator

public ComparableAggregator(int positionToAggregate,
                            TypeInformation<T> typeInfo,
                            AggregationFunction.AggregationType aggregationType,
                            boolean first,
                            ExecutionConfig config)

ComparableAggregator

public ComparableAggregator(String field,
                            TypeInformation<T> typeInfo,
                            AggregationFunction.AggregationType aggregationType,
                            boolean first,
                            ExecutionConfig config)

Method Detail

reduce

public T reduce(T value1,
                T value2)
         throws Exception

Description copied from interface: ReduceFunction

The core method of ReduceFunction, combining two values into one value of the same type. The reduce function is consecutively applied to all values of a group until only a single value remains.

Parameters:

value1 - The first value to combine.

value2 - The second value to combine.

Returns:

The combined value of both input values.

Throws:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.