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org.apache.crunch.lib
Class SecondarySort

java.lang.Object
  org.apache.crunch.lib.SecondarySort

public class SecondarySort
extends Object

Utilities for performing a secondary sort on a PTable<K, Pair<V1, V2>> collection.

Secondary sorts are usually performed during sessionization: given a collection of events, we want to group them by a key (such as a user ID), then sort the grouped records by an auxillary key (such as a timestamp), and then perform some additional processing on the sorted records.

Constructor Summary

SecondarySort()

Method Summary

static <K,V1,V2,U,V> PTable<U,V>	sortAndApply(PTable<K,Pair<V1,V2>> input, DoFn<Pair<K,Iterable<Pair<V1,V2>>>,Pair<U,V>> doFn, PTableType<U,V> ptype) Perform a secondary sort on the given PTable instance and then apply a DoFn to the resulting sorted data to yield an output PTable<U, V>.
static <K,V1,V2,T> PCollection<T>	sortAndApply(PTable<K,Pair<V1,V2>> input, DoFn<Pair<K,Iterable<Pair<V1,V2>>>,T> doFn, PType<T> ptype) Perform a secondary sort on the given PTable instance and then apply a DoFn to the resulting sorted data to yield an output PCollection<T>.

Methods inherited from class java.lang.Object

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

Constructor Detail

SecondarySort

public SecondarySort()

Method Detail

sortAndApply

public static <K,V1,V2,T> PCollection<T> sortAndApply(PTable<K,Pair<V1,V2>> input,
                                                      DoFn<Pair<K,Iterable<Pair<V1,V2>>>,T> doFn,
                                                      PType<T> ptype)

Perform a secondary sort on the given PTable instance and then apply a DoFn to the resulting sorted data to yield an output PCollection<T>.

sortAndApply

public static <K,V1,V2,U,V> PTable<U,V> sortAndApply(PTable<K,Pair<V1,V2>> input,
                                                     DoFn<Pair<K,Iterable<Pair<V1,V2>>>,Pair<U,V>> doFn,
                                                     PTableType<U,V> ptype)

Perform a secondary sort on the given PTable instance and then apply a DoFn to the resulting sorted data to yield an output PTable<U, V>.