This example is demonstrating the use of node uniqueness. Below an imaginary domain graph with Principals that own pets that are descendant to other pets.

Figure 4.6. Descendants Example Graph

In order to return all descendants of Pet0 which have the relation owns to Principal1 (Pet1 and Pet3), the Uniqueness of the traversal needs to be set to NODE_PATH rather than the default NODE_GLOBAL so that nodes can be traversed more that once, and paths that have different nodes but can have some nodes in common (like the start and end node) can be returned.

final Node target = data.get().get( "Principal1" );
TraversalDescription td = Traversal.description()
        .uniqueness( Uniqueness.NODE_PATH )
        .evaluator( new Evaluator()
{
    @Override
    public Evaluation evaluate( Path path )
    {
        if ( path.endNode().equals( target ) )
        {
            return Evaluation.INCLUDE_AND_PRUNE;
        }
        return Evaluation.EXCLUDE_AND_CONTINUE;
    }
} );

Traverser results = td.traverse( start );

This will return the following paths:

(3)--[descendant,0]-->(1)<--[owns,3]--(5)
(3)--[descendant,2]-->(4)<--[owns,5]--(5)

Let’s create a new TraversalDescription from the old one, having NODE_GLOBAL uniqueness to see the difference.

	Tip
	The TraversalDescription object is immutable, so we have to use the new instance returned with the new uniqueness setting.

TraversalDescription nodeGlobalTd = td.uniqueness( Uniqueness.NODE_GLOBAL );
results = nodeGlobalTd.traverse( start );

Now only one path is returned:

(3)--[descendant,0]-->(1)<--[owns,3]--(5)

Full source code: UniquenessOfPathsTest.java