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TuringDB’s shortestPath processor runs a Dijkstra search from a source set of nodes to a target set of nodes, returning the shortest distance and the path taken based on a numeric edge weight property.

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Sample dataset

The examples on this page use a small railway network. Run the following query to create it: 
CREATE (asch:Station {name:"Ashchurch"}),
  (bmv:Station {name:"Bromsgrove"}),
  (cnm:Station {name:"Cheltenham Spa"}),
  (dtw:Station {name:"Droitwich Spa"}),
  (hby:Station {name:"Hartlebury"}),
  (psh:Station {name:"Pershore"}),
  (wop:Station {name:"Worcestershire Parkway"}),
  (wof:Station {name:"Worcester Foregate Street"}),
  (wos:Station {name:"Worcester Shrub Hill"})
CREATE (asch)-[:LINK {distance: 7.25}]->(cnm),
  (asch)-[:LINK {distance: 11.29}]->(wop),
  (asch)-[:LINK {distance: 14.75}]->(wos),
  (bmv)-[:LINK {distance: 31.14}]->(cnm),
  (bmv)-[:LINK {distance: 6.16}]->(dtw),
  (bmv)-[:LINK {distance: 12.6}]->(wop),
  (dtw)-[:LINK {distance: 5.64}]->(hby),
  (dtw)-[:LINK {distance: 6.03}]->(wof),
  (dtw)-[:LINK {distance: 5.76}]->(wos),
  (psh)-[:LINK {distance: 4.16}]->(wop),
  (wop)-[:LINK {distance: 3.71}]->(wos),
  (wof)-[:LINK {distance: 0.65}]->(wos)

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Syntax

shortestPath(sourceSet, targetSet, edgePropName, distanceReturnVar, pathReturnVar)
ParameterDescription
sourceSetVariable bound to the source node(s) via a preceding MATCH clause
targetSetVariable bound to the target node(s) via a preceding MATCH clause
edgePropNameName of the numeric edge property to use as weight
distanceReturnVarOutput variable name for the total shortest distance
pathReturnVarOutput variable name for the path string

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Basic usage

MATCH (n{name:"Ashchurch"}), (m{name:"Worcestershire Parkway"})
shortestPath(n, m, distance, dist, path)
RETURN dist, path

+-------+--------------+
| dist  | path         |
+-------+--------------+
| 11.29 | (0)-[1]->(6) |
+-------+--------------+

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Returning only the distance or only the path

Both output variables are always computed — you can choose to return one or both: 
MATCH (n{name:"Ashchurch"}), (m{name:"Worcestershire Parkway"})
shortestPath(n, m, distance, dist, path)
RETURN dist

+-------+
| dist  |
+-------+
| 11.29 |
+-------+

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Multiple sources or targets

You can pass multiple nodes to the source or target set — shortestPath will find the shortest distance across all combinations and return the best one: 
MATCH (n), (m{name:"Worcestershire Parkway"})
WHERE n.name = "Bromsgrove" OR n.name = "Cheltenham Spa"
shortestPath(n, m, distance, dist, path)
RETURN dist, path

+------+--------------+
| dist | path         |
+------+--------------+
| 12.6 | (1)-[5]->(6) |
+------+--------------+

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Limitations

Variables passed to shortestPath as source or target cannot be used in the RETURN clause — they are consumed by the processor. The following query will produce an error:
MATCH (n{name:"Ashchurch"}), (m{name:"Worcestershire Parkway"})
shortestPath(n, m, distance, dist, path)
RETURN dist, path, n

PLAN_ERROR: Unexpected exception: projection variable n not found in output column
You can still MATCH additional nodes outside of the source and target sets and include them in RETURN. The result will be a cartesian product with the shortest path output:
MATCH (n{name:"Ashchurch"}), (m{name:"Worcestershire Parkway"}), (p{name:"Cheltenham Spa"})
shortestPath(n, m, distance, dist, path)
RETURN dist, path, p.name

+-------+--------------+----------------+
| dist  | path         | p.name         |
+-------+--------------+----------------+
| 11.29 | (0)-[1]->(6) | Cheltenham Spa |
+-------+--------------+----------------+