Hi, I have been looking at performance options for Neo4j as presently I have been observing a number of performance issues. I am still investigating the way to get the best performance out of what I am doing, and one thing it might be are longer running transactions stopping other work going on (but thats an aside to what this message is about).
One of the things that I investigated using was the IndexedRelationship work by Niels. Thought I would give a bit of feedback, although I haven't quite got this implemented at present. 1) I had to change the IndexedRelationshipExpander to be a public class in order to use it outside the package its in. 2) IndexedRelationship assumes only one tree root per node, whereas the expander allows for multiple (IndexedRelationship uses getSingleRelationship vs expander using getRelationships then matching on tree name). Having multiple would obviously be good as it means you could have two types of relationships covered by IndexedRelationship's. 3) Might pay to make it clear in the Javadocs for IndexedRelationship that the comparator can't be an anonymous inner class. Then I have some questions about usage of this. First a little background of the model I have, from reading a few things it seems quite standard. There are a lot of "document" nodes each of which have a relationship with multiple "tag" nodes. Documents generally have in the order of 10-20 tags, and tags can have as few as 1 document and sometimes tens of thousands. When tags are viewed through the UI they are almost always displayed with a descending date ordered list of documents. Seemed to be to fit quite well with IndexedRelationship. 1) I was thinking of having a switch over point at say around 500 documents for a given node where I will switch from using normal relationships to an IndexedRelationship as I was thinking at small numbers of relationships normal relationships would be quicker. Would that be correct, or not worth it? 2) On the tag end (which is the incoming end of the document-tag relationship) I was going to use a IndexedRelationshipExpander which would cover the case of whether the relationship was done through normal relationships, or through an IndexedRelationship. I also need to get a set of tags from the document end where their may be both normal relationships, and relationships coming from multiple IndexedRelationship's. From looking at it IndexedRelationshipExpander doesn't cover the reverse direction, but I would imagine using a relationship expander here would be correct. What would the best way of doing this be? As an aside it may be a good idea to note in the configuration settings page: http://wiki.neo4j.org/content/Configuration_Settings#Optimizing_for_traversals_example that -XX:+UseNUMA only works when using the Parallel Scavenger garbage collector (default or -XX:+UseParallelGC) not the concurrent mark and sweep one. Based on Cheers Bryce _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
