Neo4j cypher - search for nodes with no path between them

Question

I'm trying to find a generic way to search for a node or set of nodes which does not have a link to a another node or set of nodes. As an example, I was able to find all the nodes of a specific type (eg :Style ) which are connected somehow to a specific set of nodes (eg :MetadataRoot ), with the following:

match (root:MetadataRoot),
(n:Style),
p=shortestPath((root)-[*]-(n))
return p

Using this, I was able to subtract the set of all :Style nodes from the nodes returned by the above query, but that doesn't seem like the best way to go about this.

Answer 1

If you know the label of the start nodes you can use the EXISTS function :

MATCH (n:Style)
WHERE NOT EXISTS((n)-[]-())
RETURN n

If you know the end node :

MATCH (n:Style)
WHERE NOT EXISTS ((n)-[*]-(:MetadataRoot))
RETURN n

EDIT :

Not sure, but regarding the performance issues in your comment, a workaround could be something like this :

MATCH p=allShortestPaths((n:Style)-[*]-(:MetadataRoot))
WITH nodes(p) as nodesRelated
MATCH (s:Style) WHERE NOT s IN nodesRelated

Answer 2

This should be way faster and it should need less resources to execute:

MATCH (n:Style),
OPTIONAL MATCH p=shortestPath((:MetadataRoot)-[*0..40]-(n))
WITH n, p 
WHERE p IS NULL 
RETURN n ```