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What does parameters limit and maxLevel mean in Neo4j apoc query?

By reading the official Neo4j documentation, I can't understand what does the two parameters limit and maxLevel mean in a apoc.path.subgraphnodes.

https://neo4j-contrib.github.io/neo4j-apoc-procedures/3.5/path-finding/path-expander/

Anyone can help me ?

Thanks in advance

Solution

  • maxLevel is basically the depth of the expansion. maxLevel:2 means up to two expansions from the starting node.

    limit limits the total results returned from the call, once this many results are found, then it will stop looking further.

    So as an example, if we had a social graph, and you wanted to find the first 3 :Doctor nodes, within 10 expansions of you (this uses breadth first expansion by default), you might use something like:

    MATCH (me:Person {id:12345})
CALL apoc.path.subgraphNodes(me, {maxLevel:10, limit:3, labelFilter:'Doctor'}) YIELD node
RETURN node

    And there might be thousands of :Doctor nodes within 10 hops, but because of the limit:3, once 3 are found it will stop trying to find more.