Neo4j Cypher query running endlessly

Question

I have rerun the query below multiple times for the last two days and the Neo4j interface says it's running but it seems like it is running endlessly. I have run other queries which have all return an output. I left the query running for 9 hours and it was still running after 9 hr. I'm not sure what the issue is but would appreciate any help. I'm running Neo4j-community-2.3.12 which is an older version but it should work as I am following a tutorial and the rest of the queries work fine.

Cypher script - which is very basic:

match p=(ione)-[:ResponseTo*]->(itwo)
where length(p)=9 with p
match (u)-[:CreateChat]->(i)
where i in nodes(p)
return count(distinct u);

Image of query running endlessly:

Answer 1

This query looks like an endless loop.

I would suggest instead of getting all the paths and checking length later get the paths of the desired length(9).

Also, consider adding labels in path query.

match p=(ione)-[:ResponseTo*9]->(itwo)
with p
match (u)-[:CreateChat]->(i)
where i in nodes(p)
return count(distinct u); 

Answer 2

As Raj noted, you will want to use labels in this, as right now this is doing an all nodes scan which isn't performant.

We can also make sure the second match is more performant by ensuring we start i with the previously matched nodes, rather than applying that as a filter after the match:

match p=(ione)-[:ResponseTo*9]->(itwo)
unwind nodes(p) as i
with DISTINCT i
match (u)-[:CreateChat]->(i)
return count(distinct u);