[[query-dsl-parent-id-query]]
=== Parent Id Query

added[5.0.0]

The `parent_id` query can be used to find child documents which belong to a particular parent.
Given the following mapping definition:

[source,js]
--------------------------------------------
PUT /my_index
{
    "settings": {
        "mapping.single_type": false
    },
    "mappings": {
        "blog_post": {
            "properties": {
                "name": {
                    "type": "keyword"
                }
            }
        },
        "blog_tag": {
            "_parent": {
                "type": "blog_post"
            },
            "_routing": {
                "required": true
            }
        }
    }
}

------------------------------------------
// CONSOLE
// TESTSETUP

[source,js]
--------------------------------------------------
GET /my_index/_search
{
    "query": {
        "parent_id" : {
            "type" : "blog_tag",
            "id" : "1"
        }
    }
}
--------------------------------------------------
// CONSOLE

The above is functionally equivalent to using the following
<<query-dsl-has-parent-query, `has_parent`>> query, but performs
better as it does not need to do a join:

[source,js]
--------------------------------------------------
GET /my_index/_search
{
  "query": {
    "has_parent": {
      "parent_type": "blog_post",
        "query": {
          "term": {
            "_id": "1"
        }
      }
    }
  }
}
--------------------------------------------------
// CONSOLE

==== Parameters

This query has two required parameters:

[horizontal]
`type`::  The **child** type. This must be a type with `_parent` field.

`id`::    The required parent id select documents must referrer to.

`ignore_unmapped`::  When set to `true` this will ignore an unmapped `type` and will not match any
documents for this query. This can be useful when querying multiple indexes
which might have different mappings. When set to `false` (the default value)
the query will throw an exception if the `type` is not mapped.
