Generalized subqueries in Cypher 9

Question

I have a graph in Neo4j, where all nodes and edges have a property p. With a cypher query as follows, I get a subgraph of the whole graph that fulfills several conditions on p for vertices and edges in general.

Q1

MATCH (n)
WHERE n.p ... // some conditions for nodes
OPTIONAL MATCH (n)-[r]-()
WHERE r.p ... // some conditions for relationships
RETURN n,r

Now I want to execute a second query Q2 on the resulting subgraph of the first query Q1. For example

Q2

MATCH (a:Person)-[:knows*5]-(b:Person)-[s:studiedAt]-(u:University),
      (b)-[:owns]-(i:Business)
WHERE i.city = "Boston"
RETURN DISTINCT a.name, i.name, u.name

I do not want to apply the general conditions of Q1 for each vertex and edge in Q2. That complicates the query, loses the generalization, and needs path variables for variable paths like [:knows*5].

Is there a smarter way to execute a query Q2 on the result of a query Q1? Or is this impossible in Cypher because of its missing composability and the fact, that the result is always a table and never a graph?

user_12368154 · Answer

It's not present directly in Cypher as far as I know, but if you are using Neo4j Enterprise, then you can use Neo4j Graph Data Science Library, to create named subgraphs, and then you can query those subgraphs. The disadvantage that comes with this approach is your subgraph won't be updated as the original graph gets updated. Please go through the following documentation, on how to create a subgraph:

Generalized subqueries in Cypher 9

1 Answers