Hey,
> How would I go about retrieving all nodes for a certain relationship Type
> (ie. assuming I don't know any of them nodes) ?
Use an index. I don't know in native Neo4j off the top of my head, but the
analogous to this in Blueprints:
g.getIndex("edges", Edge.class).get("label",myType)
Indices allow you to group edges of similar label together.
See ya,
Marko.
http://markorodriguez.com
On Jul 20, 2011, at 12:54 PM, cyuczi eekc wrote:
> (in java code, the other
> variants rest/cypher I will probably not need to use)
> ie. rel.getAllNodes(Direction.INCOMING)
> or rel.getAllNodes(Direction.OUTGOING)
> or Direction.BOTH even
> But this is basically equivalent with retrieving all relationships that are
> of the specified relationship-type. So this would be more accurate:
> rel.getAllRelationships(); where rel is the Relationship of the type that we
> want and the getAllRelationships() would return something that would be a
> list of all relationship of that type (in the entire database I guess)
>
> but possibly _*without*_ having to iterate (or traverse?) all nodes(i guess
> starting from the reference node?), in order to find if each has the
> relationship type I'm looking for. (I haven't yet fully looked at traverse
> but I know it needs a starting node, even though this could probably be the
> reference node[?]; this makes me wonder if there's a traverser for
> relationships instead of just nodes - I am unsure where to look [maybe just
> pointing me there would be enough of a reply to this; thanks])
>
> The way I see it, the fact that relationships have a type is an extra layer
> on top of the relationships (just as indexing is extra(independent) layer on
> top of nodes or relationships). So I see the relationships each being unique
> (especially since I can add the same-type relationship to the same two
> nodes, more than 1 time) and they are somehow coalesced together via the
> relationship-type. It's like the relationship-type is a set which contains a
> bunch of relationships (which are obviously unique ie. unique ID) and this
> set constitutes a relationship-type. So since it's a set (probably stored as
> key-value pairs on the low level) one could potentially just get the
> elements via an iterator or something (but I also want to know how many aka
> size or count, relationships are there, of this type). (what I find a bit
> odd though, is that you can have more than one relationship for the same two
> nodes (1: A->B ; 2: A->B ), although dwins(on irc) implied that this is
> allowed because each relationship can have key-value pairs(properties)
> associated with it, and thus one could use same key for each relationship
> but with different values, but the practicality for this escapes me)
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