# Package org.apache.hadoop.mapred.join

- Interface Summary
  Interface | Description
  --- | ---
  ComposableInputFormat<K extends WritableComparable,V extends Writable> | Refinement of InputFormat requiring implementors to provide ComposableRecordReader instead of RecordReader.
  ComposableRecordReader<K extends WritableComparable,V extends Writable> | Additional operations required of a RecordReader to participate in a join.
  ResetableIterator<T extends Writable> | This defines an interface to a stateful Iterator that can replay elements added to it directly.

- Class Summary
  Class | Description
  --- | ---
  ArrayListBackedIterator<X extends Writable> | This class provides an implementation of ResetableIterator.
  CompositeInputFormat<K extends WritableComparable> | An InputFormat capable of performing joins over a set of data sources sorted and partitioned the same way.
  CompositeInputSplit | This InputSplit contains a set of child InputSplits.
  CompositeRecordReader<K extends WritableComparable,V extends Writable,X extends Writable> | A RecordReader that can effect joins of RecordReaders sharing a common key type and partitioning.
  InnerJoinRecordReader<K extends WritableComparable> | Full inner join.
  JoinRecordReader<K extends WritableComparable> | Base class for Composite joins returning Tuples of arbitrary Writables.
  MultiFilterRecordReader<K extends WritableComparable,V extends Writable> | Base class for Composite join returning values derived from multiple sources, but generally not tuples.
  OuterJoinRecordReader<K extends WritableComparable> | Full outer join.
  OverrideRecordReader<K extends WritableComparable,V extends Writable> | Prefer the "rightmost" data source for this key.
  Parser | Very simple shift-reduce parser for join expressions.
  Parser.Node |
  Parser.NodeToken |
  Parser.NumToken |
  Parser.StrToken |
  Parser.Token | Tagged-union type for tokens from the join expression.
  StreamBackedIterator<X extends Writable> | This class provides an implementation of ResetableIterator.
  TupleWritable | Writable type storing multiple `Writable`s.
  WrappedRecordReader<K extends WritableComparable,U extends Writable> | Proxy class for a RecordReader participating in the join framework.

- Enum Summary
  Enum | Description
  --- | ---
  Parser.TType |

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