org.apache.crunch.lib.join

Class DefaultJoinStrategy<K,U,V>

java.lang.Object

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

All Implemented Interfaces:

Serializable, JoinStrategy<K,U,V>

public class DefaultJoinStrategy<K,U,V>
extends Object
implements JoinStrategy<K,U,V>

Default join strategy that simply sends all data through the map, shuffle, and reduce phase.

This join strategy is full-featured (i.e. all methods are available), but is not highly efficient due to its passing all data through the shuffle phase.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
DefaultJoinStrategy()
DefaultJoinStrategy(int numReducers)

Method Summary

Methods

Modifier and Type	Method and Description
PTable<K,Pair<U,V>>	join(PTable<K,U> left, PTable<K,V> right, JoinFn<K,U,V> joinFn) Perform a default join on the given PTable instances using a user-specified JoinFn.
PTable<K,Pair<U,V>>	join(PTable<K,U> left, PTable<K,V> right, JoinType joinType) Join two tables with the given join type.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultJoinStrategy

public DefaultJoinStrategy()

DefaultJoinStrategy

public DefaultJoinStrategy(int numReducers)

Method Detail

join

public PTable<K,Pair<U,V>> join(PTable<K,U> left,
                       PTable<K,V> right,
                       JoinType joinType)

Description copied from interface: JoinStrategy

Join two tables with the given join type.

Specified by:

join in interface JoinStrategy<K,U,V>

Parameters:

left - left table to be joined

right - right table to be joined

joinType - type of join to perform

Returns:

joined tables

join

public PTable<K,Pair<U,V>> join(PTable<K,U> left,
                       PTable<K,V> right,
                       JoinFn<K,U,V> joinFn)

Perform a default join on the given PTable instances using a user-specified JoinFn.

Parameters:

left - left table to be joined

right - right table to be joined

joinFn - The user-specified implementation of the JoinFn class

Returns:

joined tables