org.apache.crunch.fn
Class MapKeysFn<K1,K2,V>
java.lang.Object
org.apache.crunch.DoFn<Pair<K1,V>,Pair<K2,V>>
org.apache.crunch.fn.MapKeysFn<K1,K2,V>
- All Implemented Interfaces:
- Serializable
public abstract class MapKeysFn<K1,K2,V>
- extends DoFn<Pair<K1,V>,Pair<K2,V>>
- See Also:
- Serialized Form
MapKeysFn
public MapKeysFn()
process
public void process(Pair<K1,V> input,
Emitter<Pair<K2,V>> emitter)
- Description copied from class:
DoFn
- Processes the records from a
PCollection
.
Note: Crunch can reuse a single input record object whose content
changes on each DoFn.process(Object, Emitter)
method call. This
functionality is imposed by Hadoop's Reducer implementation: The framework will reuse the key and value
objects that are passed into the reduce, therefore the application should
clone the objects they want to keep a copy of.
- Specified by:
process
in class DoFn<Pair<K1,V>,Pair<K2,V>>
- Parameters:
input
- The input record.emitter
- The emitter to send the output to
map
public abstract K2 map(K1 k1)
Copyright © 2012 The Apache Software Foundation. All Rights Reserved.