How do I find disconnected nodes on neo4j with Cypher?

Question

I am toying with neo4j and noticed that all Cypher queries need a starting point in the START clause. I was wondering how can I find all disconnected nodes using Cypher ?

thanks

Answer 1

If all your nodes are indexed (e.g. via auto-indexing) you could use an index query as a start point and then find those nodes that have no outgoing relationships.

start n=node:node_auto_index("id:*")
match n-[r?]->m
where r is null
return n

Nowadays I would rather use:

start n=node:node_auto_index("id:*")
where not (n-->m)
return n