Get distinct value of multiple dimension in druid

Hello , I want distinct dimensions value from druid in a single query

same query in MySQL

select (select group_concat(distinct user_id) from sites) as user_id, (select group_concat(distinct site_name) from sites) as site_name;
Is it possible in druid to make such type of query.

For a single dimension, we make this query in druid

{
    "queryType": "topN",
    "dataSource": 'xxxx',
    "intervals": "2016-10-27T14:59:48+00:00/2016-11-24T14:59:48+00:00",
    "granularity": "all",
    "dimension": 'advertised_device_os',
    "metric": "count",
    "threshold": 50000,
    "filter": {
        "fields": [
            {
                "type": "selector",
                "dimension": "sid",
                "value": "1"
            },
            {
                "type": "selector",
                "dimension": "aid",
                "value": "1"
            }
        ],
        "type": "and"
    },
    "aggregations": [
        {
            "type": "cardinality",
            "name": "count",
            "fieldNames": ["advertised_device_os"]
        }
    ]
}

So for getting multiple dimension distinct value we need to run query multiple time with different dimensions. But we want to receive multiple dimension in a single query.

Thanks

Pooja Yadav