Hi, Mattias, I just wanted to give you my thanks for the help, I really appreciate you taking the time. As you proposed, I will manage tmp data outside the graph.
SH On Mon, Nov 21, 2011 at 7:30 AM, Mattias Persson <matt...@neotechnology.com>wrote: > Den söndagen den 20:e november 2011 skrev Sébastien HARISPE< > harispe.sebast...@gmail.com>: > > Hello, > > Sorry for the delay in responding, I was busy these days. > > > > Marko > > I will test the proposed stack Thx! > > > > Mattias > > I work on graph based semantic similarity/proximity measures. > > In this case the graph is most of the time a reduction of an ontology i.e > a > > DAG corresponding to the rdfs:SubClassOf backbone of the specification. > > Most of proposed measures use set of ancestors/descendants and require a > > transitive reduction as preprocess... > > I just wanted to known if Neo4J proposed facilities to store temporaly > data > > during a traversal or if I have to manage them by myself. > > The closest would be to begin transaction and modify the graph as you go > along to later rollback the transaction. The problem is that you would lock > those parts of the graph during that transaction. So it might be better to > manage it outside the graph if you'd like to have concurrent traversals > over the same subset of the graph > > > > Thanks a lot > > > > SH > > > > On Wed, Nov 16, 2011 at 9:21 AM, Mattias Persson > > <matt...@neotechnology.com>wrote: > > > >> 2011/11/13 Sébastien HARISPE <harispe.sebast...@gmail.com> > >> > >> > Hi all, > >> > > >> > First of all, Thx a lot for your amazing work, simply astonishing... > >> > Below three questions related to my interest in using Neo4J as a Graph > DB > >> > on top of which I want to test algorithms dedicated to large semantic > >> > graphs (OWL/RDF based). > >> > It would be nice if you could help me answer them. > >> > > >> > > >> > A -Using Neo4J with semantic web technologies like RDF/OWL/SPARQL: > >> > > >> > How does Neo4J interact with these technologies? > >> > > >> > I found/read: > >> > > >> > - an old post explaining how to load OWL into Neo4J using Jena API > >> > [1]< > >> > > >> > http://sujitpal.blogspot.com/2009/05/using-neo4j-to-load-and-query-owl.html > >> > > > >> > . > >> > - interesting classes in the org.neo4j.meta.model package > >> > [2<http://components.neo4j.org/neo4j-meta-model/snapshot/> > >> > ,3< > >> > > >> > > http://components.neo4j.org/neo4j-meta-model-import/snapshot/apidocs/org/neo4j/meta/input/owl/Owl2GraphDb.html > >> > >] > >> > but I can't locate the package in the 1.5 apidocs > >> > [4]<http://components.neo4j.org/neo4j/1.5/apidocs/> > >> > . > >> > - that the org.neo4j.rdf and org.neo4j.meta do not follow the core > >> > components release, are they currently supported? > >> > - a ticket related to the addition of SPARQL plugin to the Neo4J > >> server, > >> > which means that semantic processes are part of your preoccupations > ;). > >> > > >> > Can you detail the position of Neo4J considering OWL/RDF/SPARQL > >> > technologies? > >> > I can't easily find documentation about Neo4J and OWL > >> > [5<http://wiki.neo4j.org/content/OWL,_SPARQL,_SAIL,_and_RDF>], > >> > the use of RDF and SPARQL is well detailed however > >> > [6]<http://wiki.neo4j.org/content/RDF_/_SPARQL_Quickstart_Guide> > >> > . > >> > I also read about Sail on top of Neo4j > >> > [7]<https://github.com/datablend/neo4j-sail-test>, > >> > and to be honest, I'm quite lost... > >> > > >> > Do you think Neo4J is an interesting solution to interact with these > >> > technologies, that is to say, loading OWL specification as graph > >> > (simplification of the spec e.g classes, instances relationships > between > >> > them), adding RDF triplet and using SPARQL? > >> > > >> > > >> > > >> > B - Algorithm implementations: > >> > > >> > As you know many graph algorithms need to store temporary results e.g. > >> > Dijkstra stores shortest path cost for all nodes during execution. > >> > Due to the size of the graphs, storing this information in memory is > not > >> > possible most of the time, so how do you manage this information? > >> Temporary > >> > node properties? Is there guidance to implement algorithms using > Neo4J? > >> > > >> > For extremely big traversal that could be a problem and the algorithms > >> that come with Neo4j (Dijkstra, A*, Shortest path etc.) don't use > temporary > >> properties. How big traversals are we talking about? I know I've done A* > on > >> rather many millions of relationships/nodes. Most algorithms touch only > a > >> fraction of the full graph of course so that's usually not a problem > even > >> if there are a billion relationships. > >> > >> > > >> > > >> > C - In-memory usage of Neo4J: > >> > > >> > In-memory graphs are very pleasant in order to perform certain CPU > >> > consuming algorithmic treatments on a reduced part of the graph. > >> > Considering an old post > >> > [8]< <http://lists.neo4j.org/pipermail/user/2010-February/002719.html > > > > -- > Mattias Persson, [matt...@neotechnology.com] > Hacker, Neo Technology > www.neotechnology.com > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
