cascading.pipe.joiner
Class OuterJoin

java.lang.Object
  cascading.pipe.joiner.OuterJoin

All Implemented Interfaces:

Joiner, Serializable

public class OuterJoin
extends Object
implements Joiner

Class OuterJoin will return an OuterJoin.JoinIterator that will iterate over a given Joiner and return tuples that represent and outer join of the CoGrouper internal grouped tuple collections.

Joins perform based on the equality of the join keys. In the case of null values, Java treats two null values as equivalent. SQL does not treat null values as equal. To produce SQL like results in a given join, a new Comparator will need to be used on the joined values to prevent null from equaling null. As a convenience, see the NullNotEquivalentComparator class.

See Also:

Serialized Form

Nested Class Summary

static class

OuterJoin.JoinIterator

Constructor Summary

OuterJoin()

Method Summary

Iterator<Tuple>	getIterator(JoinerClosure closure) Returns an iterator that joins the given CoGroupClosure co-groups.
int	numJoins() Returns the number of joins this instance can handle.

Methods inherited from class java.lang.Object

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

Constructor Detail

OuterJoin

public OuterJoin()

Method Detail

getIterator

public Iterator<Tuple> getIterator(JoinerClosure closure)

Description copied from interface: Joiner

Returns an iterator that joins the given CoGroupClosure co-groups.

Specified by:

getIterator in interface Joiner

Parameters:

closure - of type GroupClosure

Returns:

an iterator

numJoins

public int numJoins()

Description copied from interface: Joiner

Returns the number of joins this instance can handle. A value of -1 denotes there is no limit.

Specified by:

numJoins in interface Joiner

Returns:

an int