org.apache.flink.api.java.operators

Class SortedGrouping<T>

java.lang.Object

org.apache.flink.api.java.operators.Grouping<T>

org.apache.flink.api.java.operators.SortedGrouping<T>

Type Parameters:

T - The type of the elements of the sorted and grouped DataSet.

public class SortedGrouping<T>
extends Grouping<T>

SortedGrouping is an intermediate step for a transformation on a grouped and sorted DataSet.
The following transformation can be applied on sorted groups:

• reduceGroup(org.apache.flink.api.common.functions.GroupReduceFunction),

Field Summary

Fields inherited from class org.apache.flink.api.java.operators.Grouping

customPartitioner, dataSet, keys

Constructor Summary

Constructors

Constructor and Description
SortedGrouping(DataSet<T> set, Keys<T> keys, int field, Order order)
SortedGrouping(DataSet<T> set, Keys<T> keys, String field, Order order)

Method Summary

Methods

Modifier and Type	Method and Description
GroupReduceOperator<T,T>	first(int n) Returns a new set containing the first n elements in this grouped and sorted DataSet.
protected int[]	getGroupSortKeyPositions()
protected Order[]	getGroupSortOrders()
<R> GroupReduceOperator<T,R>	reduceGroup(GroupReduceFunction<T,R> reducer) Applies a GroupReduce transformation on a grouped and sorted DataSet. The transformation calls a RichGroupReduceFunction for each group of the DataSet.
SortedGrouping<T>	sortGroup(int field, Order order) Sorts Tuple elements within a group on the specified field in the specified Order. Note: Only groups of Tuple or Pojo elements can be sorted. Groups can be sorted by multiple fields by chaining sortGroup(int, Order) calls.
SortedGrouping<T>	sortGroup(String field, Order order) Sorts Tuple or POJO elements within a group on the specified field in the specified Order. Note: Only groups of Tuple or Pojo elements can be sorted. Groups can be sorted by multiple fields by chaining sortGroup(String, Order) calls.
SortedGrouping<T>	withPartitioner(Partitioner<?> partitioner) Uses a custom partitioner for the grouping.

Methods inherited from class org.apache.flink.api.java.operators.Grouping

getCustomPartitioner, getDataSet, getKeys

Methods inherited from class java.lang.Object

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

Constructor Detail

SortedGrouping

public SortedGrouping(DataSet<T> set,
              Keys<T> keys,
              int field,
              Order order)

SortedGrouping

public SortedGrouping(DataSet<T> set,
              Keys<T> keys,
              String field,
              Order order)

Method Detail

getGroupSortKeyPositions

protected int[] getGroupSortKeyPositions()

getGroupSortOrders

protected Order[] getGroupSortOrders()

withPartitioner

public SortedGrouping<T> withPartitioner(Partitioner<?> partitioner)

Uses a custom partitioner for the grouping.

Parameters:

partitioner - The custom partitioner.

Returns:

The grouping object itself, to allow for method chaining.

reduceGroup

public <R> GroupReduceOperator<T,R> reduceGroup(GroupReduceFunction<T,R> reducer)

Applies a GroupReduce transformation on a grouped and sorted DataSet.
The transformation calls a RichGroupReduceFunction for each group of the DataSet. A GroupReduceFunction can iterate over all elements of a group and emit any number of output elements including none.

Parameters:

reducer - The GroupReduceFunction that is applied on each group of the DataSet.

Returns:

A GroupReduceOperator that represents the reduced DataSet.

See Also:

RichGroupReduceFunction, GroupReduceOperator, DataSet

first

public GroupReduceOperator<T,T> first(int n)

Returns a new set containing the first n elements in this grouped and sorted DataSet.

Parameters:

n - The desired number of elements for each group.

Returns:

A ReduceGroupOperator that represents the DataSet containing the elements.

sortGroup

public SortedGrouping<T> sortGroup(int field,
                          Order order)

Sorts Tuple elements within a group on the specified field in the specified Order.
Note: Only groups of Tuple or Pojo elements can be sorted.
Groups can be sorted by multiple fields by chaining sortGroup(int, Order) calls.

Parameters:

field - The Tuple field on which the group is sorted.

order - The Order in which the specified Tuple field is sorted.

Returns:

A SortedGrouping with specified order of group element.

See Also:

Tuple, Order

sortGroup

public SortedGrouping<T> sortGroup(String field,
                          Order order)

Sorts Tuple or POJO elements within a group on the specified field in the specified Order.
Note: Only groups of Tuple or Pojo elements can be sorted.
Groups can be sorted by multiple fields by chaining sortGroup(String, Order) calls.

Parameters:

field - The Tuple or Pojo field on which the group is sorted.

order - The Order in which the specified field is sorted.

Returns:

A SortedGrouping with specified order of group element.

See Also:

Tuple, Order