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

Direct Known Subclasses:

InnerJoinRecordReader, OuterJoinRecordReader

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

Base class for Composite joins returning Tuples of arbitrary Writables.

Field Summary

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

conf, jc, key, keyclass, kids, value

Constructor Summary

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

Method Summary

TupleWritable	createValue() Create instance of value.
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 Detail

JoinRecordReader

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

Throws:

IOException

Method Detail

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()

Description copied from class: ComposableRecordReader

Create instance of value.

getDelegate

protected ResetableIterator<TupleWritable> getDelegate()

Return an iterator wrapping the JoinCollector.

Specified by:

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