cypher - Unexpected relation and node COUNT in Neo4j

Question

Whenever I am using a query to get the count of a specific node, I always get the number greater than 1 even though there is only one distinct type of that node existing.

Sample query:

MATCH (p)-[rel]->(v:myDistinctNode) RETURN COUNT(v)

Output: 80

MATCH (p)-[rel]->(v:myDistinctNode) RETURN COUNT(DISTINCT v)

Output: 1

I see different results while using DISTINCT, but I cannot use DISTINCT all the time. Why I am seeing this and how can I avoid it? Thanks! Neo4j Kernel-Version: 3.5.14

question from:https://stackoverflow.com/questions/65924012/unexpected-relation-and-node-count-in-neo4j

Answer 1

The short answer is that you need to use a collect statement to make it work.

MATCH (p)<-[rel]-(v:myDistinctNode) WITH collect(v) AS nodes RETURN count(nodes)

This should return one. I'm not a cypher expert, but I believe the reason it doesn't work is that the cypher result seems more like a table where in one row you have p, another row you have r, and the last row you have v. Even though v is a unique entity, there are still 80 rows that have v.