Hi, Tobias. I was only referring to the case when it was the intent to delete the node also. In that case, you *have* to delete all the relationships to the node in order to delete the node. No worries, it is easy enough to implement!
-----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Tobias Ivarsson Sent: Sunday, April 25, 2010 5:53 PM To: Neo user discussions Subject: Re: [Neo] Checking if relationship exists between two nodes On Sun, Apr 25, 2010 at 10:42 PM, Mattias Persson <matt...@neotechnology.com > wrote: > 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 > I think just removing all relationships of a node is a bit unsafe. I would prefer if you had to supply the RelationshipTypes to delete, so that you don't destroy unexpected structures. SomeUtilityClass.delete( Node node, RelationshipType... expectedTypes ) > > > > > -----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 > -- Tobias Ivarsson <tobias.ivars...@neotechnology.com> Hacker, Neo Technology www.neotechnology.com Cellphone: +46 706 534857 _______________________________________________ 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
