cascading.pipe.joiner

Class InnerJoin

java.lang.Object

cascading.pipe.joiner.BaseJoiner

cascading.pipe.joiner.InnerJoin

All Implemented Interfaces:

DeclaresResults, Joiner, java.io.Serializable

public class InnerJoin
extends BaseJoiner

Class InnerJoin will return an Iterator that will iterate over a given Joiner and return tuples that represent and inner 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

Nested Classes

Modifier and Type	Class and Description
static class	InnerJoin.JoinIterator

Constructor Summary

Constructors

Constructor and Description
InnerJoin()
InnerJoin(Fields fieldDeclaration)

Method Summary

Methods

Modifier and Type	Method and Description
java.util.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 cascading.pipe.joiner.BaseJoiner

getFieldDeclaration

Methods inherited from class java.lang.Object

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

Constructor Detail

InnerJoin

public InnerJoin()

InnerJoin

@ConstructorProperties(value="fieldDeclaration")
public InnerJoin(Fields fieldDeclaration)

Method Detail

getIterator

public java.util.Iterator<Tuple> getIterator(JoinerClosure closure)

Description copied from interface: Joiner

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

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.

Returns:

an int