elasticsearch/docs/reference/query-languages/query-dsl-has-parent-query.md

navigation_title	mapped_pages
Has parent	https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-has-parent-query.html

Has parent query [query-dsl-has-parent-query]

Returns child documents whose joined parent document matches a provided query. You can create parent-child relationships between documents in the same index using a join field mapping.

::::{warning} Because it performs a join, the has_parent query is slow compared to other queries. Its performance degrades as the number of matching parent documents increases. Each has_parent query in a search can increase query time significantly.

::::

Example request [has-parent-query-ex-request]

Index setup [has-parent-index-setup]

To use the has_parent query, your index must include a join field mapping. For example:

PUT /my-index-000001
{
  "mappings": {
    "properties": {
      "my-join-field": {
        "type": "join",
        "relations": {
          "parent": "child"
        }
      },
      "tag": {
        "type": "keyword"
      }
    }
  }
}

Example query [has-parent-query-ex-query]

GET /my-index-000001/_search
{
  "query": {
    "has_parent": {
      "parent_type": "parent",
      "query": {
        "term": {
          "tag": {
            "value": "Elasticsearch"
          }
        }
      }
    }
  }
}

Top-level parameters for has_parent [has-parent-top-level-params]

parent_type

(Required, string) Name of the parent relationship mapped for the join field.

query

(Required, query object) Query you wish to run on parent documents of the parent_type field. If a parent document matches the search, the query returns its child documents.

score

(Optional, Boolean) Indicates whether the relevance score of a matching parent document is aggregated into its child documents. Defaults to false.

If false, {{es}} ignores the relevance score of the parent document. {{es}} also assigns each child document a relevance score equal to the query's boost, which defaults to 1.

If true, the relevance score of the matching parent document is aggregated into its child documents' relevance scores.

ignore_unmapped

(Optional, Boolean) Indicates whether to ignore an unmapped parent_type and not return any documents instead of an error. Defaults to false.

If false, {{es}} returns an error if the parent_type is unmapped.

You can use this parameter to query multiple indices that may not contain the parent_type.

Notes [has-parent-query-notes]

Sorting [has-parent-query-performance]

You cannot sort the results of a has_parent query using standard sort options.

If you need to sort returned documents by a field in their parent documents, use a function_score query and sort by _score. For example, the following query sorts returned documents by the view_count field of their parent documents.

GET /_search
{
  "query": {
    "has_parent": {
      "parent_type": "parent",
      "score": true,
      "query": {
        "function_score": {
          "script_score": {
            "script": "_score * doc['view_count'].value"
          }
        }
      }
    }
  }
}