Problem about node filter according to another node with distance of 2

Users
3

The query for this would be like

{
  var(func: eq(name, "United States")) {
    ~locatedIn {  isHere as ~locatedIn { name } }
  }

  query(func: eq(name, "Bob")) {
      friendNot_In_US : friend @filter(NOT uid(isHere)) {
          name
          locatedIn { name }
      }
  }
}

The response

{
  "data": {
    "query": [
      {
        "friendNot_In_US": [
          {
            "name": [
              "Lilian"
            ],
            "locatedIn": [
              {
                "name": [
                  "Quebec"
                ]
              }
            ]
          }
        ]
      }
    ]
  }
}

But there’s a problem here. If you query like this. You gonna receive internally all Persons who live in the US, it could be millions - for small context is okay tho. In general, this isn’t performative. In this case, UID_IN would be very handy. But we need support Add support of Value Variables for uid_in. · Issue #3066 · dgraph-io/dgraph · GitHub for variables.

The sample created to test this

{
   "set":[
      {
         "uid":"_:Bob",
         "dgraph.type":"Person",
         "name":"Bob",
         "telephone":"(425) 123-4567",
         "friend":[
            {
               "uid":"_:Julian"
            },
            {
               "uid":"_:Lilian"
            }
         ],
         "locatedIn":[
            {
               "uid":"_:SF"
            }
         ]
      },
      {
         "uid":"_:Julian",
         "dgraph.type":"Person",
         "name":"Julian",
         "telephone":"(425) 322-0551",
         "friend":[
            {
               "uid":"_:Bob"
            },
            {
               "uid":"_:Lilian"
            }
         ],
         "locatedIn":[
            {
               "uid":"_:SF"
            }
         ]
      },
      {
         "uid":"_:Lilian",
         "dgraph.type":"Person",
         "name":"Lilian",
         "telephone":"(425) 322-0551",
         "friend":[
            {
               "uid":"_:Bob"
            },
            {
               "uid":"_:Julian"
            }
         ],
         "locatedIn":[
            {
               "uid":"_:Quebec"
            }
         ]
      },
      {
         "uid":"_:US",
         "dgraph.type":"Country",
         "name":"United States"
      },
      {
         "uid":"_:CAD",
         "dgraph.type":"Country",
         "name":"Canada"
      },
      {
         "uid":"_:Quebec",
         "dgraph.type":"City",
         "name":"Quebec",
         "locatedIn":[
            {
               "uid":"_:CAD"
            }
         ]
      },
      {
         "uid":"_:SF",
         "dgraph.type":"City",
         "name":"San Francisco",
         "locatedIn":[
            {
               "uid":"_:US"
            }
         ]
      }
   ]
}