﻿---
title: Has child query
description: Returns parent documents whose joined child documents match a provided query. You can create parent-child relationships between documents in the same...
url: https://www.elastic.co/elastic/docs-builder/docs/2649/reference/query-languages/query-dsl/query-dsl-has-child-query
products:
  - Elasticsearch
---

# Has child query
Returns parent documents whose [joined](https://www.elastic.co/elastic/docs-builder/docs/2649/reference/elasticsearch/mapping-reference/parent-join) child documents match a provided query. You can create parent-child relationships between documents in the same index using a [join](https://www.elastic.co/elastic/docs-builder/docs/2649/reference/elasticsearch/mapping-reference/parent-join) field mapping.
<warning>
  Because it performs a join, the `has_child` is slow compared to other queries. Its performance degrades as the number of matching child documents pointing to unique parent documents increases. Each `has_child` query in a search can increase query time significantly.If you care about query performance, do not use this query. If you need to use the `has_child` query, use it as rarely as possible.
</warning>


## Example request


### Index setup

To use the `has_child` query, your index must include a [join](https://www.elastic.co/elastic/docs-builder/docs/2649/reference/elasticsearch/mapping-reference/parent-join) field mapping. For example:
```json

{
  "mappings": {
    "properties": {
      "my-join-field": {
        "type": "join",
        "relations": {
          "parent": "child"
        }
      }
    }
  }
}
```


### Example query

```json

{
  "query": {
    "has_child": {
      "type": "child",
      "query": {
        "match_all": {}
      },
      "max_children": 10,
      "min_children": 2,
      "score_mode": "min"
    }
  }
}
```


## Top-level parameters for `has_child`

<definitions>
  <definition term="type">
    (Required, string) Name of the child relationship mapped for the [join](https://www.elastic.co/elastic/docs-builder/docs/2649/reference/elasticsearch/mapping-reference/parent-join) field.
  </definition>
  <definition term="query">
    (Required, query object) Query you wish to run on child documents of the `type` field. If a child document matches the search, the query returns the parent document.
  </definition>
  <definition term="ignore_unmapped">
    (Optional, Boolean) Indicates whether to ignore an unmapped `type` and not return any documents instead of an error. Defaults to `false`.
  </definition>
</definitions>

If `false`, Elasticsearch returns an error if the `type` is unmapped.
You can use this parameter to query multiple indices that may not contain the `type`.
<definitions>
  <definition term="max_children">
    (Optional, integer) Maximum number of child documents that match the `query` allowed for a returned parent document. If the parent document exceeds this limit, it is excluded from the search results.
  </definition>
  <definition term="min_children">
    (Optional, integer) Minimum number of child documents that match the `query` required to match the query for a returned parent document. If the parent document does not meet this limit, it is excluded from the search results.
  </definition>
  <definition term="score_mode">
    (Optional, string) Indicates how scores for matching child documents affect the root parent document’s [relevance score](/elastic/docs-builder/docs/2649/reference/query-languages/query-dsl/query-filter-context#relevance-scores). Valid values are:
  </definition>
  <definition term="none (Default)">
    Do not use the relevance scores of matching child documents. The query assigns parent documents a score of `0`.
  </definition>
  <definition term="avg">
    Use the mean relevance score of all matching child documents.
  </definition>
  <definition term="max">
    Uses the highest relevance score of all matching child documents.
  </definition>
  <definition term="min">
    Uses the lowest relevance score of all matching child documents.
  </definition>
  <definition term="sum">
    Add together the relevance scores of all matching child documents.
  </definition>
</definitions>


## Notes


### Sorting

You cannot sort the results of a `has_child` query using standard [sort options](https://www.elastic.co/elastic/docs-builder/docs/2649/reference/elasticsearch/rest-apis/sort-search-results).
If you need to sort returned documents by a field in their child documents, use a `function_score` query and sort by `_score`. For example, the following query sorts returned documents by the `click_count` field of their child documents.
```json

{
  "query": {
    "has_child": {
      "type": "child",
      "query": {
        "function_score": {
          "script_score": {
            "script": "_score * doc['click_count'].value"
          }
        }
      },
      "score_mode": "max"
    }
  }
}
```