I already used the regular index to lookup for existing relationships as workaround. it's definitely faster then looping specially when database is growing. it will be really useful to have an index for relationships.
-------------------------------------------------- From: "Mattias Persson" <[email protected]> Sent: Thursday, October 28, 2010 10:48 AM To: "Neo4j user discussions" <[email protected]> Subject: Re: [Neo4j] Node.hasRelationship question > 2010/10/28 Walaa Eldin Moustafa <[email protected]> > >> Hi Mattias, >> >> Even if I pass nulls, I will still have to build an index on some key >> (property). I do not want to do that because it adds the property >> index overhead for something that I am not actually using. >> > > I think it's definately worth that tiny extra overhead since lookups are > very fast (no looping at all, but instead direct index lookups). > > >> >> By the way, does the underlying code for index.get(kay, value, start, >> end) iterate over all the relationships of start and checks if one is >> connected to end, or it does perform a direct look up to get the edges >> between (start, end)? >> > > No looping, just a direct lookup. Maybe RelationshipIndex should have a > method: > > add( Relationship relationship ); > > which indexes that relationship (with its start/end node as usual) but w/o > any additional property. Would that be a good idea? > > >> >> Thanks. >> >> >> On Wed, Oct 27, 2010 at 4:50 PM, Mattias Persson >> <[email protected]> wrote: >> > 2010/10/27, Walaa Eldin Moustafa <[email protected]>: >> >> I am looking for a method that is if given a node n1, can answer the >> >> query if n1 has a relationship of type t with node n2, something along >> >> the lines of: >> >> >> >> boolean b = n1.hasRelatioship(n2,t); >> >> >> >> I know we can answer this question by iterating over n1's >> >> getRelationships() and testing them. However, I was looking for >> >> something more efficient that does not have to iterate over the node's >> >> relationships, especially that I noticed that the RelationshipIndex >> >> interface has a get() method that does something like that; however we >> >> have to supply it with a key and a value for an attribute for the edge >> >> between the two nodes. So I was looking for something like this >> >> method, but without having to pass a key/value pair. >> >> >> > you can actually leave out key/value (pass in null) if you pass in >> > start/end node, or you can index the relationship type as a key/value >> > pair for each relationship and then do: get( "type", "knows", person1, >> > person2 ); >> > >> > would that help? >> > _______________________________________________ >> >> Neo4j mailing list >> >> [email protected] >> >> https://lists.neo4j.org/mailman/listinfo/user >> >> >> > >> > >> > -- >> > Mattias Persson, [[email protected]] >> > Hacker, Neo Technology >> > www.neotechnology.com >> > _______________________________________________ >> > Neo4j mailing list >> > [email protected] >> > https://lists.neo4j.org/mailman/listinfo/user >> > >> _______________________________________________ >> Neo4j mailing list >> [email protected] >> https://lists.neo4j.org/mailman/listinfo/user >> > > > > -- > Mattias Persson, [[email protected]] > Hacker, Neo Technology > www.neotechnology.com > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
