ArangoDB v3.12 is under development and not released yet. This documentation is not final and potentially incomplete.

Combining AQL Graph Traversals

You can combine graph queries with other AQL features like geo-spatial search

Finding the start vertex via a geo query

Our first example will locate the start vertex for a graph traversal via a geo index. We use the City Graph and its geo indexes:

Cities Example Graph

var examples = require("@arangodb/graph-examples/example-graph");
var g = examples.loadGraph("routeplanner");
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We search all german cities in a range of 400 km around the ex-capital Bonn: Hamburg and Cologne. We won’t find Paris since its in the frenchCity collection.

FOR startCity IN germanCity
  FILTER GEO_DISTANCE(@bonn, startCity.geometry) < @radius
    RETURN startCity._key
Bind Parameters
{
  "bonn": [
    7.0998,
    50.734
  ],
  "radius": 400000
}
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Let’s revalidate that the geo indexes are actually used:

FOR startCity IN germanCity
  FILTER GEO_DISTANCE(@bonn, startCity.geometry) < @radius
    RETURN startCity._key
Bind Parameters
{
  "bonn": [
    7.0998,
    50.734
  ],
  "radius": 400000
}
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And now combine this with a graph traversal:

FOR startCity IN germanCity
  FILTER GEO_DISTANCE(@bonn, startCity.geometry) < @radius
    FOR v, e, p IN 1..1 OUTBOUND startCity
      GRAPH 'routeplanner'
    RETURN {startcity: startCity._key, traversedCity: v._key}
Bind Parameters
{
  "bonn": [
    7.0998,
    50.734
  ],
  "radius": 400000
}
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The geo index query returns us startCity (Cologne and Hamburg) which we then use as starting point for our graph traversal. For simplicity we only return their direct neighbours. We format the return result so we can see from which startCity the traversal came.

Alternatively we could use a LET statement with a subquery to group the traversals by their startCity efficiently:

FOR startCity IN germanCity
  FILTER GEO_DISTANCE(@bonn, startCity.geometry) < @radius
    LET oneCity = (
      FOR v, e, p IN 1..1 OUTBOUND startCity
        GRAPH 'routeplanner' RETURN v._key
    )
      RETURN {startCity: startCity._key, connectedCities: oneCity}
Bind Parameters
{
  "bonn": [
    7.0998,
    50.734
  ],
  "radius": 400000
}
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Finally, we clean up again:

examples.dropGraph("routeplanner");
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