=> db.properties.findOne({},{address:1})
{
    "_id" : ObjectId("585b909c870d907845b695fd"),
    "address" : {
        "postcode" : "W1D 1NN",
        "address1" : "Essence",
        "address2" : "United Kingdom House",
        "county" : "London",
        "town" : "LONDON",
        "latitude" : "51.5160229933117",
        "longitude" : "-0.139088472429092",
        "house_number" : "114",
        "location" : {
            "type" : "Point",
            "coordinates" : [
                -0.139088472429092,
                51.5160229933117
            ]
        }
    }
}

=> db.properties.getIndexes()
[
    {
        "v" : 1,
        "key" : {
            "_id" : 1
        },
        "name" : "_id_",
        "ns" : "cherrydoorsync.properties"
    },
    {
        "v" : 1,
        "key" : {
            "address.location.coordinates" : "2d"
        },
        "name" : "address.location.coordinates_2d",
        "ns" : "cherrydoorsync.properties"
    }
]

db.propertiesSync.aggregate([
   {
     $geoNear: {
        near: { type: "Point", coordinates: [  -2.94379156655216, 54.8905641133194 ] },
        distanceField: "dist.calculated",
        maxDistance: 2,
        includeLocs: "dist.location",
        num: 5
     }
   }
])

assert: command failed: {
    "ok" : 0,
    "errmsg" : "geoNear command failed: { ok: 0.0, errmsg: "The featureCompatibilityVersion must be 3.4 to use collation. See http://dochub.mongodb.org/core/3.4-feature-compatibility.", code: 72, codeName: "InvalidOptions" }",
    "code" : 16604,
    "codeName" : "Location16604"
} : aggregate failed
_getErrorWithCode@src/mongo/shell/utils.js:25:13
doassert@src/mongo/shell/assert.js:16:14
assert.commandWorked@src/mongo/shell/assert.js:370:5
DBCollection.prototype.aggregate@src/mongo/shell/collection.js:1319:5
@(shell):1:1

2017-01-20T13:41:27.914+0530 E QUERY    [main] Error: command failed:     {
    "ok" : 0,
    "errmsg" : "geoNear command failed: { ok: 0.0, errmsg: "The featureCompatibilityVersion must be 3.4 to use collation. See http://dochub.mongodb.org/core/3.4-feature-compatibility.", code: 72, codeName: "InvalidOptions" }",
    "code" : 16604,
    "codeName" : "Location16604"
} : aggregate failed :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
doassert@src/mongo/shell/assert.js:16:14
assert.commandWorked@src/mongo/shell/assert.js:370:5
DBCollection.prototype.aggregate@src/mongo/shell/collection.js:1319:5
@(shell):1:1

> db.adminCommand( { setFeatureCompatibilityVersion: <"3.4" } )
2017-01-20T13:45:39.023+0530 E QUERY    [main] SyntaxError: expected expression, got '<' @(shell):1:51