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InnerJoinFn (Apache Crunch 0.9.0 API)

Class InnerJoinFn<K,U,V>

  extended by org.apache.crunch.DoFn<Pair<Pair<K,Integer>,Iterable<Pair<U,V>>>,Pair<K,Pair<U,V>>>
      extended by org.apache.crunch.lib.join.JoinFn<K,U,V>
          extended by org.apache.crunch.lib.join.InnerJoinFn<K,U,V>
Type Parameters:
K - Type of the keys.
U - Type of the first PTable's values
V - Type of the second PTable's values
All Implemented Interfaces:

public class InnerJoinFn<K,U,V>
extends JoinFn<K,U,V>

Used to perform the last step of an inner join.

See Also:
Serialized Form

Field Summary
Fields inherited from class org.apache.crunch.lib.join.JoinFn
keyType, leftValueType
Constructor Summary
InnerJoinFn(PType<K> keyType, PType<U> leftValueType)
Method Summary
 String getJoinType()
 void initialize()
          Initialize this DoFn.
 void join(K key, int id, Iterable<Pair<U,V>> pairs, Emitter<Pair<K,Pair<U,V>>> emitter)
          Performs the actual joining.
Methods inherited from class org.apache.crunch.lib.join.JoinFn
Methods inherited from class org.apache.crunch.DoFn
cleanup, configure, disableDeepCopy, getConfiguration, getContext, getCounter, getCounter, getStatus, getTaskAttemptID, increment, increment, increment, increment, progress, scaleFactor, setConfiguration, setContext, setStatus
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public InnerJoinFn(PType<K> keyType,
                   PType<U> leftValueType)
Method Detail


public void initialize()
Description copied from class: DoFn
Initialize this DoFn. This initialization will happen before the actual DoFn.process(Object, Emitter) is triggered. Subclasses may override this method to do appropriate initialization.

Called during the setup of the job instance this DoFn is associated with.

initialize in class JoinFn<K,U,V>


public void join(K key,
                 int id,
                 Iterable<Pair<U,V>> pairs,
                 Emitter<Pair<K,Pair<U,V>>> emitter)
Description copied from class: JoinFn
Performs the actual joining.

Specified by:
join in class JoinFn<K,U,V>
key - The key for this grouping of values.
id - The side that this group of values is from (0 -> left, 1 -> right).
pairs - The group of values associated with this key and id pair.
emitter - The emitter to send the output to.


public String getJoinType()
Specified by:
getJoinType in class JoinFn<K,U,V>
The name of this join type (e.g. innerJoin, leftOuterJoin).

Copyright © 2014 The Apache Software Foundation. All Rights Reserved.