Neo4J/Cypher: is it possibile to filter the length of a path in the where clause?

Question

Let's suppose we have this simple pattern:

p=(a)-[r]-(b)

where nodes a and b have their own properties already set in the WHERE clause (eg a:Movie AND a.title = "The Matrix" AND b:Movie). I'd like to add another condition in the WHERE clause like

LEGHT(p) =2 OR LENGTH(p)>6

(not the correct syntax, I know)

As far as I know, it is possibile to specify the length of a path in the MATCH clause with the syntax [r*min..max] but that doesn't cover the case I'm looking for.

Any help would be appreciated =)

Answer 1

Yes, that does work in neo4j, exactly as you've specified.

Sample data:

create (a:Foo)-[:stuff]->(b:Foo)-[:stuff]->(c:Foo);

Then this query:

MATCH p=(x:Foo)-[:stuff*]->(y:Foo) 
WHERE length(p)>1 RETURN p;

Returns only the 2-step path from a->b->c and not either one-step path ( a->b or b->c )

Answer 2

Does this work for you?

MATCH p=(a)-[r*2..]-(b)
WHERE LENGTH(r) = 2 OR LENGTH(r) > 6
RETURN p

Note that with a large DB this query can take a very long time, or not finish, since the MATCH clause does not set an upper bound on the path length.