2010/4/25, Rick Bullotta <rick.bullo...@burningskysoftware.com>: > Cool, Mattias. I just ran into that requirement again today. > > This is also another good case for the cached/persisted "number of > relationships" counter on a node that has also been discussed. It would > enable the optimization to occur automatically. Although for this method it doesn't matter, sort of, because it'll iterate from both nodes in parallell (unless it immediately finds it from the first direction, within the first 50 or so) > > Another API function that would be useful (though it is also easy to > implement) is one that automatically deletes all relationships for a node, > then deletes the node, since that is the required path of action anyway to > delete a node. > well, yeah maybe. I don't think I've ever wanted to do that so I haven't created a utility method for it. But it may be time to add it > > > -----Original Message----- > From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On > Behalf Of Mattias Persson > Sent: Sunday, April 25, 2010 3:52 PM > To: Neo4j user discussions > Subject: [Neo] Checking if relationship exists between two nodes > > As you all (probably) know the Neo4j API has no method > Node#hasRelationshipTo(Node otherNode) and to find out such a thing could > potentially be slow if both the nodes has many relationships (of the > type/direction you want to check). > > I just created a utility for that which starts to iterate from the node (of > the two) that the developer thinks/knows has the least relationships. If a > certain amount of relationships have been iterated and not yet found a new > thread is spawned which starts to iterate from the other node in the > opposite direction. The method will return as soon as the first thread finds > a match. I'd guess that's the fastest way currently to do that. The next > level of this would be to add indexing for relationships (which is an > upcoming feature) and go via that instead. > > So the code may look like: > > (it's in the neo4j-utils component) > > GraphDatabaseUtil graphDbUtil = new GraphDatabaseUtil( graphDb ); > boolean exists = graphDbUtil.relationshipExistsBetween( node1, node2, > MyRelTypes.MY_TYPE, Direction.OUTGOING ); > > -- > Mattias Persson, [matt...@neotechnology.com] > Hacker, Neo Technology > www.neotechnology.com > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user >
-- Mattias Persson, [matt...@neotechnology.com] Hacker, Neo Technology www.neotechnology.com _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
