Hopefully someone has a better way, but as I've been running into bottlenecks like this, I've been adding node properties. As in, if there's a single relationship (that you care about) with edge id 33 between nodes 1 and 2, I'd add a property "edge" to node 1 that's the array [2,33] and vice-versa for node 2. This totally breaks the graphness and treats it more like an object db but with some wrapper code it's not too much of a hassle.
Better might be the edge indexer like you mentioned, or long-term I wonder if Neo4j will support hypergraphs? That's an instance where it'd be useful, I think. You could have a "list root" node pointing to all the edges you care about and only iterate through those. But those aren't short term solutions. Does someone have a better one? I'd learn from it too. :) - Jeff Klann On Thu, Sep 2, 2010 at 1:23 PM, Paul A. Jackson <[email protected]> wrote: > I'm looking for an efficient way to find an (the) edge(s) between two > nodes. > > I have a requirement that when I add an edge between two specific nodes > that I first determine if the edge already exists, which leads to the need > for a method that return such an edge given the subject and object. Since I > was unable to find such a method I attempted to create my own, which worked, > but has become the performance bottleneck in the code. > private Relationship getSingeRelationship(Node subject, Node object, > RelationshipType relationshipType, String key) > { > for (Relationship relationship : getCommonRelationships(subject, object, > relationshipType, Direction.OUTGOING)) > { > boolean currentHasIndex = relationship.hasProperty(EDGE_INDEX_KEY); > if (key == null) > { > if (!currentHasIndex) > { > return relationship; > } > } > else > { > if (currentHasIndex && > key.equals(relationship.getProperty(EDGE_INDEX_KEY))) > { > return relationship; > } > } > } > return null; > } > > ...where getCommonRelationships returns an Iterable<Relationship> and > simply loops through all the subject's relationships (of the specified > relationship type and direction) until it finds an edge that points to the > given object node. The profiler says the 2/3 of the time is spent in > org.neo4j.kernel.impl.core.IntArrayIterator.hasNext() and most of the rest > is spent in org.neo4j.kernel.impl.core.RelationshipProxy.getOtherNode(Node). > > I am aware of the lab code that is supposed to support indexed edges and > could see using that as a solution, but I was hoping for something native > (and merged into the 1.1-SNAPSHOT branch). > > Are there any better approaches? > > Thanks, > -Paul > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
