Are there any restrictions on Amazon neptune when using gremlin syntax?

Question

I am using a graph database for my project, Neptune by AWS. Neptune uses gremlin syntax for graph queries. I was trying to execute a scenario where I have to filter the outgoing edges from a vertex on the basis of property on the edge. Let's call that property 'x'. The value of this property 'x' is of the form 'abc::xyz::ref'. This is to store multiple values on the edge, as Neptune does not allow multi values on edges. I have to do a contains check with three combinations and an exact match :-

'abc::'
'::abc'
'::abc::'
Exact match with 'abc'

I was trying to use filter command in the gremlin in my java code. The below code works fine with TinkerGraph in-memory, but when I connect it with Neptune and run the same query it throws some parsing exception.

 String valueToCheck = "abc";
 List<String> listOfValuesToCheck = new ArrayList<>();
 listOfValuesToCheck.add("::abc");
 listOfValuesToCheck.add("abc::");
 listOfValuesToCheck.add("::abc::");
 GraphTraversal<Vertex, Map<Object, Object>> gt24 = g.V().outE().has("x").filter(it -> { 
      String value = String.valueOf(it.get().value("x"));
      if(value.equals(valueToCheck)){
      return true;
      }else {
        for(String s: listOfValuesToCheck){
            if(value.contains(s){
            return true;
            }
        }
      }
    }).valueMap().with(WithOptions.tokens);
    
    while (gt24.hasNext()) {
      System.out.println(gt24.next());
    }

Does someone know, why this is happening with Neptune? And is there a better way to do it that works with Neptune.
I have seen one more instance where Neptune did not throw an error but also gave back no results but the same work with TinkerGraph.

y - property on Edge
z - property on Vertex

GraphTraversal<Vertex, Map<String, Object>> gt13 = g.V(1, 2).project("id", "summary").by(T.id)
        .by(__.outE().has("y", "e").inV().group().by("z"));

noam621 noam621 · Accepted Answer · 2020-06-29T11:35:55

Neptune doesn't support lambdas steps.

you should try to replace your lambda code with other gremlin steps.

g.V().outE().has("x").or(
        __.has('prop', 'abc'),
        __.has('prop', TextP.containing('abc::')),
        __.has('prop', TextP.containing('::abc')),
    ).valueMap().with(WithOptions.tokens)

example: https://gremlify.com/sjrd9lrwfr

Are there any restrictions on Amazon neptune when using gremlin syntax?

2 Answers