Stats aggregation

A multi-value metrics aggregation that computes stats over numeric values extracted from the aggregated documents.

The stats that are returned consist of: min, max, sum, count and avg.

Assuming the data consists of documents representing exams grades (between 0 and 100) of students

POST /exams/_search?size=0
{
  "aggs": {
    "grades_stats": { "stats": { "field": "grade" } }
  }
}

The above aggregation computes the grades statistics over all documents. The aggregation type is stats and the field setting defines the numeric field of the documents the stats will be computed on. The above will return the following:

{
  ...

  "aggregations": {
    "grades_stats": {
      "count": 2,
      "min": 50.0,
      "max": 100.0,
      "avg": 75.0,
      "sum": 150.0
    }
  }
}

The name of the aggregation (grades_stats above) also serves as the key by which the aggregation result can be retrieved from the returned response.

POST /exams/_search
{
  "size": 0,
  "runtime_mappings": {
    "grade.weighted": {
      "type": "double",
      "script": """
        emit(doc['grade'].value * doc['weight'].value)
      """
    }
  },
  "aggs": {
    "grades_stats": {
      "stats": {
        "field": "grade.weighted"
      }
    }
  }
}

POST /exams/_search?size=0
{
  "aggs": {
    "grades_stats": {
      "stats": {
        "field": "grade",
        "missing": 0      
      }
    }
  }
}