Elasticsearch Avg Aggregation

POST /exams/_search?size=0
{
  "aggs": {
    "avg_grade": { "avg": { "field": "grade" } }
  }
}

返回值
{
  ...
  "aggregations": {
    "avg_grade": {
      "value": 75.0
    }
  }
}

Script

POST /exams/_search?size=0
{
  "aggs": {
    "avg_grade": {
      "avg": {
        "script": {
          "source": "doc.grade.value"
        }
      }
    }
  }
}


 POST /exams/_search?size=0
{
  "aggs": {
    "avg_grade": {
      "avg": {
        "script": {
          "id": "my_script",
          "params": {
            "field": "grade"
          }
        }
      }
    }
  }
}

Value Script

POST /exams/_search?size=0
{
  "aggs": {
    "avg_corrected_grade": {
      "avg": {
        "field": "grade",
        "script": {
          "lang": "painless",
          "source": "_value * params.correction",
          "params": {
            "correction": 1.2
          }
        }
      }
    }
  }
}

Messing Value

POST /exams/_search?size=0
{
  "aggs": {
    "grade_avg": {
      "avg": {
        "field": "grade",
        "missing": 10     
      }
    }
  }
}




Histogram fields 

PUT metrics_index/_doc/1
{
  "network.name" : "net-1",
  "latency_histo" : {
      "values" : [0.1, 0.2, 0.3, 0.4, 0.5], 
      "counts" : [3, 7, 23, 12, 6] 
   }
}

PUT metrics_index/_doc/2
{
  "network.name" : "net-2",
  "latency_histo" : {
      "values" :  [0.1, 0.2, 0.3, 0.4, 0.5], 
      "counts" : [8, 17, 8, 7, 6] 
   }
}

POST /metrics_index/_search?size=0
{
  "aggs": {
    "avg_latency":
      { "avg": { "field": "latency_histo" }
    }
  }
}

返回值
{
  ...
  "aggregations": {
    "avg_latency": {
      "value": 0.29690721649
    }
  }
}