使用Traversal查询Azure Cosmos DB图

Question

I am trying to use Traversal to query an Azure Cosmos DB graph as follows

val cluster = Cluster.build(File("remote.yaml")).create()
val client = cluster.connect()

val graph = EmptyGraph.instance()
val g = graph.traversal().withRemote(DriverRemoteConnection.using(cluster))

val traversal = g.V().count()
val aliased = client.alias("g")

val result = aliased.submit(traversal)

val resultList = result.all().get()

resultList.forEach { println(it) }

Problem is execution hangs after result.all().get() and never get a response. I only have this problem when submitting a traversal. When submitting a Gremlin query string directly it works properly.

Answer 1

I'm in a similar boat, but according to this recent query Does Cosmos DB support Gremlin.net c# GLV? traversals are not possible just yet. However, for those using (or thinking about using) Gremlin.NET to connect to Cosmos, I'll share some of what I've been able to do.

Firstly, I have no trouble connecting to cosmos from the gremlin console, just when using Gremlin.NET as follows:

var gremlinServer = new GremlinServer(hostname, port, enableSsl: true,                                                                 
username: "/dbs/" + database + "/colls/" + collection,                                                                
password: authKey);
var driver = new DriverRemoteConnection(new GremlinClient(gremlinServer));
//var driver = new DriverRemoteConnection(new GremlinClient(new GremlinServer("localhost", 8182)));

var graph = new Gremlin.Net.Structure.Graph();
var g = graph.Traversal().WithRemote(driver);

g.V().Drop().Next(); // nullreferenceexception

When using Gremlin.NET to work with a locally hosted gremlin server (see commented out line), all works fine.

The only way I can work with cosmos using gremlin.net is to submit queries as string literals eg

var task = gremlinClient.SubmitAsync<dynamic>("g.V().Drop()");

This works, but I want to be able to use fluent traversals.

I can work with Cosmos quite easily using the Azure/Graph API (documentclient etc), but still only with string literals. Also, this isn't very portable, and apparently slower too