Missing aggregation

The missing aggregation creates a single bucket containing all documents that do not have a value for a specified field. A document is considered missing if the field is absent, null, or an empty array. If the field mapping defines a null_value, explicit null values are indexed as that value and are not counted as missing. This aggregation is commonly paired with other bucket aggregations to account for documents that cannot be placed in any other bucket because they lack the required field.

Parameters

The missing aggregation takes the following parameters.

If the specified field is not mapped in the index, every document is counted as missing, and no error is returned. A misspelled field name therefore produces a bucket containing all documents. If the doc_count equals the total number of documents, verify the field name.

Example

The following request indexes three products into a product_ratings index. Product C has no rating field:

POST product_ratings/_bulk?refresh
{ "index": { "_id": "1" } }
{ "name": "Product A", "rating": 4.5, "num_reviews": 100 }
{ "index": { "_id": "2" } }
{ "name": "Product B", "rating": 3.8, "num_reviews": 50 }
{ "index": { "_id": "3" } }
{ "name": "Product C" }

The following aggregation counts how many products are missing a rating and includes a terms subaggregation to identify them:

GET /product_ratings/_search
{
  "size": 0,
  "aggs": {
    "without_rating": {
      "missing": {
        "field": "rating"
      },
      "aggs": {
        "names": {
          "terms": {
            "field": "name.keyword"
          }
        }
      }
    }
  }
}

Example response

The response shows that one product (Product C) is missing the rating field:

{
  ...
  "aggregations": {
    "without_rating": {
      "doc_count": 1,
      "names": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [
          {
            "key": "Product C",
            "doc_count": 1
          }
        ]
      }
    }
  }
}

Response body fields

The following table lists the response body fields.