On Fri, Dec 9, 2011 at 12:12 AM, Matt Luongo <m...@scholr.ly> wrote: > Hey everybody, > > I'm trying to write a query that returns a small subgraph around a type > system's sub-reference node, excluding relationships used to > define the in-graph type hierarchy. > > Eg, given a graph > > (0)-[:TYPE]->(1)-[:INSTANCE]->(2)-[:SOMETYPE1]->(3) > (2)-[:SOMETYPE2]->(4)-[:SOMETYPE5]->(5)-[:SOMETYPE6]->(6) > (7)-[:SOMETYPE7]->(2) > > I'd like to get all paths from length 0 to 5 from node (2), excluding those > that start with the 'INSTANCE' relationship type. > > I started with > > `START a = node(2) MATCH p = (a -[g*0..5]->b) WHERE not(type(g) = > "INSTANCE") RETURN p`, which doesn't seem to be valid. >
You are not the first one to run into this. "g" is an iterable of relationships, and not a single relationship. Maybe we should make this a valid query... Anyway, with Cypher as it works today, you have to do this: START a = node(2) MATCH p = (a -[g*0..5]->b) WHERE ALL(r in g WHERE not(type(r) ="INSTANCE") RETURN p Thinking about this, it would be trivial to translate your query to this query under the hood. WDYT? Then I realized that even if it were, this statement would still traverse > across the reference node (potentially hitting supernodes in the > type hierarchy) because where clauses are evaluated after traversals. > No, the pattern matcher evaluates predicates as soon as the necessary parts have been found, with a few exceptions. Filtering after the fact would be much more expensive. I think the very first version of Cypher did do this, but it's been changed for quite some time now. Andrés _______________________________________________ NOTICE: THIS MAILING LIST IS BEING SWITCHED TO GOOGLE GROUPS, please register and consider posting at https://groups.google.com/forum/#!forum/neo4j Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
