Neo4j更高效的Cypher查询，用于查找具有关系的连接节点

Question

I have a patch where I know a starting and end node with an unknown number of nodes between the 2. I wish to collect a collection of nodes and each nodes exiting relationship in the chain.

PROFILE MATCH p = (:Question{id:'1234'})-[:Answer*0..3]->(t)-
[:Answer]->(:Question{id:'5678'})
WHERE t:Set OR t:Read
OPTIONAL MATCH (x)-[v:Answer]->(y)
WHERE x.id <> '1234' and x IN nodes(p) AND v IN rels(p)
return x,v

This query is pretty inefficient as the OPTIONAL MATCH (x)-[v:Answer]->(y) requires a full nodes scan.

I know that t and as a result x will be of types Set or Read which would reduce the scan quite a bit but don't think there is a way to query this.

Is there any way to optimise this?

Answer 1

You can simply unwind the path you have already got:

MATCH p = (:Question{id:'1234'})-[:Answer*0..3]->(t)-[:Answer]->(:Question{id:'5678'})
WHERE t:Set OR t:Read
WITH nodes(p) AS nds, 
     rels(p) AS rls
UNWIND range(1, length(nds)-2) AS i
RETURN nds[i] AS x, 
       rls[i] AS v