org.apache.flink.api.java.functions

Class SelectByMinFunction<T extends Tuple>

java.lang.Object

org.apache.flink.api.java.functions.SelectByMinFunction<T>

Type Parameters:

T -

All Implemented Interfaces:

Serializable, Function, ReduceFunction<T>

@Internal
public class SelectByMinFunction<T extends Tuple>
extends Object
implements ReduceFunction<T>

Function that enables selection by minimal value of a field.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SelectByMinFunction(TupleTypeInfo<T> type, int... fields) Constructor which is overwriting the default constructor.

Method Summary

Modifier and Type	Method and Description
T	reduce(T value1, T value2) Reduce implementation, returns smaller tuple or value1 if both tuples are equal.

Methods inherited from class java.lang.Object

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

Constructor Detail

SelectByMinFunction

public SelectByMinFunction(TupleTypeInfo<T> type,
                           int... fields)

Constructor which is overwriting the default constructor.

Parameters:

type - Types of tuple whether to check if given fields are key types.

fields - Array of integers which are used as key for comparison. The order of indexes is regarded in the reduce function. First index has highest priority and last index has least priority.

Method Detail

reduce

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

Reduce implementation, returns smaller tuple or value1 if both tuples are equal. Comparison highly depends on the order and amount of fields chosen as indices. All given fields (at construction time) are checked in the same order as defined (at construction time). If both tuples are equal in one index, the next index is compared. Or if no next index is available value1 is returned. The tuple which has a smaller value at one index will be returned.

Specified by:

reduce in interface ReduceFunction<T extends Tuple>

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.