Package org.apache.hadoop.mapreduce.lib.join

Class JoinRecordReader<K extends WritableComparable<?>>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<K,V>

org.apache.hadoop.mapreduce.lib.join.ComposableRecordReader<K,X>

org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader<K,Writable,TupleWritable>

org.apache.hadoop.mapreduce.lib.join.JoinRecordReader<K>

All Implemented Interfaces:

Closeable, AutoCloseable, Comparable<ComposableRecordReader<K,?>>, Configurable

Direct Known Subclasses:

InnerJoinRecordReader, OuterJoinRecordReader

@Public
@Stable
public abstract class JoinRecordReader<K extends WritableComparable<?>>
extends CompositeRecordReader<K,Writable,TupleWritable>

Base class for Composite joins returning Tuples of arbitrary Writables.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	org.apache.hadoop.mapreduce.lib.join.JoinRecordReader.JoinDelegationIterator	Since the JoinCollector is effecting our operation, we need only provide an iterator proxy wrapping its operation.

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader

org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader.JoinCollector

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader

conf, jc, key, keyclass, kids, value

Constructor Summary

Constructors

Constructor	Description
JoinRecordReader(int id, Configuration conf, int capacity, Class<? extends WritableComparator> cmpcl)

Method Summary

Modifier and Type	Method	Description
TupleWritable	createValue()
protected ResetableIterator<TupleWritable>	getDelegate()	Return an iterator wrapping the JoinCollector.
boolean	nextKeyValue()	Emit the next set of key, value pairs as defined by the child RecordReaders and operation associated with this composite RR.

Methods inherited from class org.apache.hadoop.mapreduce.lib.join.CompositeRecordReader

accept, add, close, combine, compareTo, createKey, createTupleWritable, fillJoinCollector, getComparator, getConf, getCurrentKey, getCurrentValue, getProgress, getRecordReaderQueue, hasNext, id, initialize, key, key, setConf, skip

Methods inherited from class java.lang.Object

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

Constructor Details

JoinRecordReader

public JoinRecordReader(int id,
 Configuration conf,
 int capacity,
 Class<? extends WritableComparator> cmpcl)
                 throws IOException

Throws:

IOException

Method Details

nextKeyValue

public boolean nextKeyValue()
                     throws IOException,
InterruptedException

Emit the next set of key, value pairs as defined by the child RecordReaders and operation associated with this composite RR.

Specified by:

nextKeyValue in class RecordReader<K extends WritableComparable<?>,TupleWritable>

Returns:

true if a key/value pair was read

Throws:

IOException

InterruptedException

createValue

public TupleWritable createValue()

getDelegate

protected ResetableIterator<TupleWritable> getDelegate()

Return an iterator wrapping the JoinCollector.

Specified by:

getDelegate in class CompositeRecordReader<K extends WritableComparable<?>,Writable,TupleWritable>