摘要：前言支持三種數(shù)據(jù)查詢類型。，，是無維度，支持單維度，支持雙維度?，F(xiàn)在有一個需求基于服務(wù)名和調(diào)用鏈的兩個維度，從獲取最大分位數(shù)的前五名數(shù)據(jù)。但是沒有排序查看官方文檔的查詢格式。官網(wǎng)上明確標(biāo)識可以通過實現(xiàn)查詢。其中可以限制返回數(shù)量。

druid支持三種數(shù)據(jù)查詢類型。timeseries，topn，groupby
timeseries是無維度，topn支持單維度，groupby支持雙維度。現(xiàn)在有一個需求：基于服務(wù)名和調(diào)用鏈的兩個維度，從druid獲取最大分位數(shù)的前五名數(shù)據(jù)。topn是單維度的。groupby是雙維度的。但是沒有排序

groupby的查詢格式。官網(wǎng)上明確標(biāo)識可以通過groupby實現(xiàn)topn查詢。

{
  "queryType": "groupBy",
  "dataSource": "sample_datasource",
  "granularity": "day",
  "dimensions": ["country", "device"],
  "limitSpec": { "type": "default", "limit": 5000, "columns": ["country", "data_transfer"] },
  "filter": {
    "type": "and",
    "fields": [
      { "type": "selector", "dimension": "carrier", "value": "AT&T" },
      { "type": "or", 
        "fields": [
          { "type": "selector", "dimension": "make", "value": "Apple" },
          { "type": "selector", "dimension": "make", "value": "Samsung" }
        ]
      }
    ]
  },
  "aggregations": [
    { "type": "longSum", "name": "total_usage", "fieldName": "user_count" },
    { "type": "doubleSum", "name": "data_transfer", "fieldName": "data_transfer" }
  ],
  "postAggregations": [
    { "type": "arithmetic",
      "name": "avg_usage",
      "fn": "/",
      "fields": [
        { "type": "fieldAccess", "fieldName": "data_transfer" },
        { "type": "fieldAccess", "fieldName": "total_usage" }
      ]
    }
  ],
  "intervals": [ "2012-01-01T00:00:00.000/2012-01-03T00:00:00.000" ],
  "having": {
    "type": "greaterThan",
    "aggregation": "total_usage",
    "value": 100
  }
}

其中l(wèi)imitspec可以限制返回數(shù)量。但是沒有說可以排序。真的無語
點擊查看limitspec的詳情http://druid.io/docs/0.12.1/q...

官方文檔還是寫的很詳細(xì)的，多看官方文檔有益身心。