Druid 可以在 Superset SQL 查询，除此之外可以通过 HTTP+JSON 查询:

curl -X POST '<host:<port>/druid/v2/?pretty' -H 'Content-Type:application/json' -H 'Accept:application/json' -d @query.json

{
  "queryType": "timeseries",
  "dataSource": "cpm_log",
  "granularity": "hour",
  "aggregations": [
    {
      "type": "longSum",
      "name": "requests",
      "fieldName": "req_count_raw"
    },
    {
      "type": "longSum",
      "name": "impressions",
      "fieldName": "win_count"
    },
    {
      "type": "floatSum",
      "name": "revenues",
      "fieldName": "win_price"
    }
  ],
  "postAggregations": [
    {
      "type":"arithmetic",
      "name": "ecpm",
      "fn": "/",
      "fields": [
        {
          "type": "fieldAccess",
          "name": "postAgg_rev",
          "fieldName": "revenues"
        },
        {
          "type": "fieldAccess",
          "name": "postAgg_imps",
          "fieldName": "impressions"
        }
      ]
    }
  ],
  "filter": {
    "type": "and",
    "fields": [
      {
        "type": "selector",
        "dimension": "device_os",
        "value": "android"
      },
      {
        "type": "in",
        "dimension": "req_ad_type",
        "values": ["banner"]
      }
    ]
  },
  "context": {
    "grandTotal": true
  },
  "intervals": [
    "2019-04-09T00:00:00+08:00/2019-04-09T23:00:00+08:00"
  ]
}
  1. queryType 有 timeseries, topN, groupBy, search, timeBoundary 等
  2. 尽量少用 groupBy 查询，效率不高
  3. topN 查询是通过 metric 来排序
  4. context 可以指定 queryId，这样可以通过 DELETE /druid/v2/{queryId} 取消查询
  5. 去重: {"type": "cardinality", "name": "distinct_pid", "fields": ["ad_pid"]}

RTFM, godruid