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

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---
navigation_title: "Has child"
mapped_pages:
- https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-has-child-query.html
---
# Has child query [query-dsl-has-child-query]
Returns parent documents whose [joined](/reference/elasticsearch/mapping-reference/parent-join.md) child documents match a provided query. You can create parent-child relationships between documents in the same index using a [join](/reference/elasticsearch/mapping-reference/parent-join.md) 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.
::::
## Example request [has-child-query-ex-request]
### Index setup [has-child-index-setup]
To use the `has_child` query, your index must include a [join](/reference/elasticsearch/mapping-reference/parent-join.md) field mapping. For example:
```console
PUT /my-index-000001
{
"mappings": {
"properties": {
"my-join-field": {
"type": "join",
"relations": {
"parent": "child"
}
}
}
}
}
```
### Example query [has-child-query-ex-query]
```console
GET /_search
{
"query": {
"has_child": {
"type": "child",
"query": {
"match_all": {}
},
"max_children": 10,
"min_children": 2,
"score_mode": "min"
}
}
}
```
## Top-level parameters for `has_child` [has-child-top-level-params]
`type`
: (Required, string) Name of the child relationship mapped for the [join](/reference/elasticsearch/mapping-reference/parent-join.md) field.
`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.
`ignore_unmapped`
: (Optional, Boolean) Indicates whether to ignore an unmapped `type` and not return any documents instead of an error. Defaults to `false`.
If `false`, {{es}} returns an error if the `type` is unmapped.
You can use this parameter to query multiple indices that may not contain the `type`.
`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.
`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.
`score_mode`
: (Optional, string) Indicates how scores for matching child documents affect the root parent documents [relevance score](/reference/query-languages/query-dsl/query-filter-context.md#relevance-scores). Valid values are:
`none` (Default)
: Do not use the relevance scores of matching child documents. The query assigns parent documents a score of `0`.
`avg`
: Use the mean relevance score of all matching child documents.
`max`
: Uses the highest relevance score of all matching child documents.
`min`
: Uses the lowest relevance score of all matching child documents.
`sum`
: Add together the relevance scores of all matching child documents.
## Notes [has-child-query-notes]
### Sorting [has-child-query-performance]
You cannot sort the results of a `has_child` query using standard [sort options](/reference/elasticsearch/rest-apis/sort-search-results.md).
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.
```console
GET /_search
{
"query": {
"has_child": {
"type": "child",
"query": {
"function_score": {
"script_score": {
"script": "_score * doc['click_count'].value"
}
}
},
"score_mode": "max"
}
}
}
```