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
Method Summary |
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. |
DefaultJoinStrategy
public DefaultJoinStrategy()
DefaultJoinStrategy
public DefaultJoinStrategy(int numReducers)
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 joinedright
- right table to be joinedjoinType
- 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 joinedright
- right table to be joinedjoinFn
- The user-specified implementation of the JoinFn
class
- Returns:
- joined tables
Copyright © 2014 The Apache Software Foundation. All Rights Reserved.