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neo4jcypherpy2neo

difference between two cypher queries

I am trying to run these two cypher queries and I am not understanding the difference between them. The purpose here is to find multiple paths between given two nodes such that the sum of transit_time in that path is in ascending order.

Q1 :

MATCH p =(:`ml`  { placeId: 960 })-[:ETA*0..10]->(:`ml`  { placeId: 814 })
return p, p as allshortestPaths, 
REDUCE(time=0, r in relationships(p) | time+r.transit_time) AS totalTime 
ORDER BY totalTime ASC

Q2 :

MATCH (from:`ml` { placeId: 960}), (to: `ml` {placeId: 814}) , 
paths = allShortestPaths((from)-[:ETA*]->(to)) 
WITH REDUCE(time = 0, rel in rels(paths) | time + rel.transit_time) 
AS totalTime, paths 
RETURN (totalTime) 
ORDER BY totalTime ASC

In this I get the best result from Q1 Also these operations take very long time. Any other better way to do that may be using graph algorithms? I think it is possible to do this using Dijkstra algorithm any help about how to specify cost_parameter there and how to use will be great. I am using py2neo and neo4j.

Solution

  • Neo4j has an integrated tool to explain queries, in fact it's not explaining but profiling.

    You can also find here some documentation about execution plan, to explain each operation.

    An example of execution plan with a complex query: Neo4j execution plan example

    source