com.bigdata.bop.join

Class JVMHashIndex.Bucket

java.lang.Object

com.bigdata.bop.join.JVMHashIndex.Bucket

All Implemented Interfaces:

Comparable<JVMHashIndex.Bucket>, Iterable<JVMHashIndex.SolutionHit>

Enclosing class:

JVMHashIndex

public static class JVMHashIndex.Bucket
extends Object
implements Iterable<JVMHashIndex.SolutionHit>, Comparable<JVMHashIndex.Bucket>

A group of solutions having the same as-bound values for the join vars. Each solution is paired with a hit counter so we can support OPTIONAL semantics for the join.

Constructor Summary

Constructors

Constructor and Description
JVMHashIndex.Bucket(int hashCode, IBindingSet solution)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(IBindingSet solution)
boolean	addDistinct(IBindingSet solution) Add the solution to the bucket iff the solutions is not already present in the bucket.
int	compareTo(JVMHashIndex.Bucket o) Orders the buckets based on their hash codes.
boolean	contains(IBindingSet bs)
int	hashCode()
boolean	isEmpty() Return true iff this JVMHashIndex.Bucket is empty (if there are no solutions in the bucket).
Iterator<JVMHashIndex.SolutionHit>	iterator()
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

JVMHashIndex.Bucket

public JVMHashIndex.Bucket(int hashCode,
                   IBindingSet solution)

Method Detail

toString

public String toString()

Overrides:

toString in class Object

add

public void add(IBindingSet solution)

addDistinct

public boolean addDistinct(IBindingSet solution)

Add the solution to the bucket iff the solutions is not already present in the bucket.

Note: There is already a hash index in place on the join variables when we are doing a DISTINCT filter. Further, only the "join" variables are "selected" and participate in a DISTINCT filter. Therefore, if we have a hash collision such that two solutions would be directed into the same JVMHashIndex.Bucket then we can not improve matters but must simply scan the solutions in the bucket to decide whether the new solution duplicates a solution which is already present.

Parameters:

solution - The solution.

Returns:

true iff the bucket was modified by this operation.

contains

public boolean contains(IBindingSet bs)

Parameters:

bs - the binding set to check

Returns:

if the bucket contains the binding set, false otherwise

iterator

public final Iterator<JVMHashIndex.SolutionHit> iterator()

Specified by:

iterator in interface Iterable<JVMHashIndex.SolutionHit>

compareTo

public final int compareTo(JVMHashIndex.Bucket o)

Orders the buckets based on their hash codes.

Specified by:

compareTo in interface Comparable<JVMHashIndex.Bucket>

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

isEmpty

public final boolean isEmpty()

Return true iff this JVMHashIndex.Bucket is empty (if there are no solutions in the bucket).