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Elastic Docs ›Elasticsearch Guide [8.15] ›Query DSL ›Joining queries

Has parent query

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Has parent query

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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.

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

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Index setup

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

resp = client.indices.create(
    index="my-index-000001",
    mappings={
        "properties": {
            "my-join-field": {
                "type": "join",
                "relations": {
                    "parent": "child"
                }
            },
            "tag": {
                "type": "keyword"
            }
        }
    },
)
print(resp)
response = client.indices.create(
  index: 'my-index-000001',
  body: {
    mappings: {
      properties: {
        "my-join-field": {
          type: 'join',
          relations: {
            parent: 'child'
          }
        },
        tag: {
          type: 'keyword'
        }
      }
    }
  }
)
puts response
const response = await client.indices.create({
  index: "my-index-000001",
  mappings: {
    properties: {
      "my-join-field": {
        type: "join",
        relations: {
          parent: "child",
        },
      },
      tag: {
        type: "keyword",
      },
    },
  },
});
console.log(response);
PUT /my-index-000001
{
  "mappings": {
    "properties": {
      "my-join-field": {
        "type": "join",
        "relations": {
          "parent": "child"
        }
      },
      "tag": {
        "type": "keyword"
      }
    }
  }
}

Example query

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resp = client.search(
    index="my-index-000001",
    query={
        "has_parent": {
            "parent_type": "parent",
            "query": {
                "term": {
                    "tag": {
                        "value": "Elasticsearch"
                    }
                }
            }
        }
    },
)
print(resp)
const response = await client.search({
  index: "my-index-000001",
  query: {
    has_parent: {
      parent_type: "parent",
      query: {
        term: {
          tag: {
            value: "Elasticsearch",
          },
        },
      },
    },
  },
});
console.log(response);
GET /my-index-000001/_search
{
  "query": {
    "has_parent": {
      "parent_type": "parent",
      "query": {
        "term": {
          "tag": {
            "value": "Elasticsearch"
          }
        }
      }
    }
  }
}

Top-level parameters for has_parent

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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, Elasticsearch ignores the relevance score of the parent document. Elasticsearch 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, Elasticsearch 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

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Sorting

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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.

resp = client.search(
    query={
        "has_parent": {
            "parent_type": "parent",
            "score": True,
            "query": {
                "function_score": {
                    "script_score": {
                        "script": "_score * doc['view_count'].value"
                    }
                }
            }
        }
    },
)
print(resp)
const response = await client.search({
  query: {
    has_parent: {
      parent_type: "parent",
      score: true,
      query: {
        function_score: {
          script_score: {
            script: "_score * doc['view_count'].value",
          },
        },
      },
    },
  },
});
console.log(response);
GET /_search
{
  "query": {
    "has_parent": {
      "parent_type": "parent",
      "score": true,
      "query": {
        "function_score": {
          "script_score": {
            "script": "_score * doc['view_count'].value"
          }
        }
      }
    }
  }
}
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