cascading.pipe.joiner
Class InnerJoin
java.lang.Object
cascading.pipe.joiner.BaseJoiner
cascading.pipe.joiner.InnerJoin
- All Implemented Interfaces:
- DeclaresResults, Joiner, Serializable
public class InnerJoin
- extends BaseJoiner
Class InnerJoin will return an InnerJoin.JoinIterator
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
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
InnerJoin
public InnerJoin()
InnerJoin
@ConstructorProperties(value="fieldDeclaration")
public InnerJoin(Fields fieldDeclaration)
getIterator
public 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
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