org.apache.hadoop.mapred.join
Interface ComposableRecordReader<K extends WritableComparable,V extends Writable>

All Superinterfaces:

Comparable<ComposableRecordReader<K,?>>, RecordReader<K,V>

All Known Implementing Classes:

InnerJoinRecordReader, JoinRecordReader, MultiFilterRecordReader, OuterJoinRecordReader, OverrideRecordReader, WrappedRecordReader

@InterfaceAudience.Public
@InterfaceStability.Stable
public interface ComposableRecordReader<K extends WritableComparable,V extends Writable>
extends RecordReader<K,V>, Comparable<ComposableRecordReader<K,?>>

Additional operations required of a RecordReader to participate in a join.

Method Summary

void	accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector jc, K key) While key-value pairs from this RecordReader match the given key, register them with the JoinCollector provided.
boolean	hasNext() Returns true if the stream is not empty, but provides no guarantee that a call to next(K,V) will succeed.
int	id() Return the position in the collector this class occupies.
K	key() Return the key this RecordReader would supply on a call to next(K,V)
void	key(K key) Clone the key at the head of this RecordReader into the object provided.
void	skip(K key) Skip key-value pairs with keys less than or equal to the key provided.

Methods inherited from interface org.apache.hadoop.mapred.RecordReader

close, createKey, createValue, getPos, getProgress, next

Methods inherited from interface java.lang.Comparable

compareTo

Method Detail

id

int id()

Return the position in the collector this class occupies.

key

K key()

Return the key this RecordReader would supply on a call to next(K,V)

key

void key(K key)
         throws IOException

Clone the key at the head of this RecordReader into the object provided.

Throws:

IOException

hasNext

boolean hasNext()

Returns true if the stream is not empty, but provides no guarantee that a call to next(K,V) will succeed.

skip

void skip(K key)
          throws IOException

Skip key-value pairs with keys less than or equal to the key provided.

Throws:

IOException

accept

void accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector jc,
            K key)
            throws IOException

While key-value pairs from this RecordReader match the given key, register them with the JoinCollector provided.

Throws:

IOException