org.apache.crunch.lib.join

Class InnerJoinFn<K,U,V>

java.lang.Object

org.apache.crunch.DoFn<Pair<Pair<K,Integer>,Iterable<Pair<U,V>>>,Pair<K,Pair<U,V>>>

org.apache.crunch.lib.join.JoinFn<K,U,V>

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:

Serializable

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

Constructor Summary

Constructors

Constructor and Description
InnerJoinFn(PType<K> keyType, PType<U> leftValueType)

Method Summary

Modifier and Type	Method and Description
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

process

Methods inherited from class org.apache.crunch.DoFn

cleanup, configure, disableDeepCopy, scaleFactor, setConfiguration, setContext

Methods inherited from class java.lang.Object

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

Constructor Detail

InnerJoinFn

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

Method Detail

initialize

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.

Overrides:

initialize in class JoinFn<K,U,V>

join

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>

Parameters:

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.

getJoinType

public String getJoinType()

Specified by:

getJoinType in class JoinFn<K,U,V>

Returns:

The name of this join type (e.g. innerJoin, leftOuterJoin).