org.apache.hadoop.mapred.join
Class JoinRecordReader<K extends WritableComparable>
java.lang.Object
org.apache.hadoop.mapred.join.CompositeRecordReader<K,Writable,TupleWritable>
org.apache.hadoop.mapred.join.JoinRecordReader<K>
- All Implemented Interfaces:
- Comparable<ComposableRecordReader<K,?>>, Configurable, ComposableRecordReader<K,TupleWritable>, RecordReader<K,TupleWritable>
- Direct Known Subclasses:
- InnerJoinRecordReader, OuterJoinRecordReader
@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class JoinRecordReader<K extends WritableComparable>
- extends CompositeRecordReader<K,Writable,TupleWritable>
- implements ComposableRecordReader<K,TupleWritable>
Base class for Composite joins returning Tuples of arbitrary Writables.
Methods inherited from class org.apache.hadoop.mapred.join.CompositeRecordReader |
accept, add, close, combine, compareTo, createInternalValue, createKey, fillJoinCollector, getComparator, getConf, getPos, getProgress, getRecordReaderQueue, hasNext, id, key, key, setConf, skip |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
JoinRecordReader
public JoinRecordReader(int id,
JobConf conf,
int capacity,
Class<? extends WritableComparator> cmpcl)
throws IOException
- Throws:
IOException
next
public boolean next(K key,
TupleWritable value)
throws IOException
- Emit the next set of key, value pairs as defined by the child
RecordReaders and operation associated with this composite RR.
- Specified by:
next
in interface RecordReader<K extends WritableComparable,TupleWritable>
- Parameters:
key
- the key to read data intovalue
- the value to read data into
- Returns:
- true iff a key/value was read, false if at EOF
- Throws:
IOException
createValue
public TupleWritable createValue()
- Create an object of the appropriate type to be used as a value.
- Specified by:
createValue
in interface RecordReader<K extends WritableComparable,TupleWritable>
- Returns:
- a new value object.
getDelegate
protected ResetableIterator<TupleWritable> getDelegate()
- Return an iterator wrapping the JoinCollector.
- Specified by:
getDelegate
in class CompositeRecordReader<K extends WritableComparable,Writable,TupleWritable>
Copyright © 2014 Apache Software Foundation. All Rights Reserved.