org.apache.cassandra.hadoop
Class ColumnFamilyOutputReducer<KEYIN,VALUEIN>
java.lang.Object
org.apache.hadoop.mapreduce.Reducer<KEYIN,VALUEIN,byte[],java.util.List<IColumn>>
org.apache.cassandra.hadoop.ColumnFamilyOutputReducer<KEYIN,VALUEIN>
- Type Parameters:
KEYIN
-
public class ColumnFamilyOutputReducer<KEYIN,VALUEIN>
- extends org.apache.hadoop.mapreduce.Reducer<KEYIN,VALUEIN,byte[],java.util.List<IColumn>>
The ColumnFamilyOutputReducer
reduces a <key, values>
pair, where the value is a generic iterable type, into a list of columns that
need to be mutated for that key, where each column corresponds to an element
in the value.
The default implementation treats the VALUEIN type to be a
ColumnWritable
, in which case this reducer acts as an identity
function.
- Author:
- Karthick Sankarachary
Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer |
org.apache.hadoop.mapreduce.Reducer.Context |
Methods inherited from class org.apache.hadoop.mapreduce.Reducer |
cleanup, run, setup |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
ColumnFamilyOutputReducer
public ColumnFamilyOutputReducer()
reduce
public void reduce(KEYIN key,
java.lang.Iterable<VALUEIN> values,
org.apache.hadoop.mapreduce.Reducer.Context context)
throws java.io.IOException,
java.lang.InterruptedException
- Overrides:
reduce
in class org.apache.hadoop.mapreduce.Reducer<KEYIN,VALUEIN,byte[],java.util.List<IColumn>>
- Throws:
java.io.IOException
java.lang.InterruptedException
map
protected ColumnWritable map(VALUEIN value)
Copyright © 2010 The Apache Software Foundation