Value Count Aggregationedit

A single-value metrics aggregation that counts the number of values that are extracted from the aggregated documents. These values can be extracted either from specific fields in the documents, or be generated by a provided script. Typically, this aggregator will be used in conjunction with other single-value aggregations. For example, when computing the avg one might be interested in the number of values the average is computed over.

{
    "aggs" : {
        "grades_count" : { "value_count" : { "field" : "grade" } }
    }
}

Response:

{
    ...

    "aggregations": {
        "grades_count": {
            "value": 10
        }
    }
}

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

Scriptedit

Counting the values generated by a script:

{
    ...,

    "aggs" : {
        "grades_count" : { "value_count" : { "script" : "doc['grade'].value" } }
    }
}

This will interpret the script parameter as an inline script with the default script language and no script parameters. To use a file script use the following syntax:

{
    ...,

    "aggs" : {
        "grades_count" : {
            "value_count" : {
                "script" : {
                    "file": "my_script",
                    "params" : {
                        "field" : "grade"
                    }
                }
            }
        }
    }
}
Tip

for indexed scripts replace the file parameter with an id parameter.