I focused the same problem. Nodes with a lot of relationships are very difficult (needs a lot of time) to be traversed. I solved the problem by grouping the relationships using additional nodes. The dense node then has only a few relationships to different 'group' nodes. Each 'group' node then has again many relationships to other nodes.
Although this helps, it is a very ugly solution. Best regards Norbert Tausch Am 29.06.2011 16:07, schrieb Niels Hoogeveen: > Recently I have worked on loading the content of DbPedia into my database and > run into a performance issue. > My application has a meta-layer; inspired by the meta model component, but > rewritten in Scala. > All DbPedia resources are said to be an instance of "topic", > creating a relationship from that resource node to the node that describes > the topic class. > This makes the "topic class" node of course densely populated. > The "topic class" node has relationships other than "HAS_INSTANCE", > for example "SUB_CLASS_OF", which states that the "topic class" node is a > subclass of "typable". > When trying to retrieve the "SUB_CLASS_OF" relationships of the "topic class" > node performance degrades enormously. > > It looks (please correct me if I am wrong in my assumption) as if all > relationships are being scanned > to filter out the "SUB_CLASS_OF" relationships (of which there are very few, > especially compared to the "HAS_INSTANCE" relationship) > I ended up placing all "HAS_INSTANCE" into the Timeline index from > Neo4j-graph-collections for two reasons,it's nice to know when a resource > became an instance of a class (bonus), and to make sure that not a single > nodebecomes heavily populated. > So far so good, but delving deeper into the Timeline index, I notice that the > relationship between an entry nodeand the root of the tree is partially > established by the use of a property on "entry node" which names the timeline > index. > The simplest way to establish the relationship between an "entry node" and > the tree root is by means of a Lucene index lookup. > This is of course not a very fastest solution and actually would mean the > same as adding a property to the "resource node", listing the classes a > resource is an instance of. > Adding a relationship from "entry node" to "tree root" in the Timeline > component would create yet another densely populated nodein the database (in > this case the tree root). > Is there a way out of this situation? > Would it be possible to partition the relationships in the database per > relationship type per direction, so densely populated nodescan get traversed > fast for those relationships types that are sparsely populated? > Niels > > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
