Nested elasticsearch agg

1-setup.yaml

# PUT localhost:9200/index

{
    "mappings": {
        "properties": {
            "nested": {
                "type": "nested",
                "properties": {
                    "values": {
                        "type": "keyword"
                    }
                }
            }
        }
    }
}

2-document-1.yaml

# PUT localhost:9200/index/_doc/1

{
    "nested": {
        "values": ["1", "2", "1"]
    }
}

3-document-2.yaml

# PUT localhost:9200/index/_doc/2

{
    "nested": {
        "values": ["1", "3"]
    }
}

4-request.yaml

# POST localhost:9200/index/_search

{
    "size": 0,
    "aggs": {
        "root": {
            "terms": {
                "field": "_id"
            },
            "aggs": {
                "values": {
                    "nested": {
                        "path": "nested"
                    },
                    "aggs": {
                        "combined": {
                            "terms": {
                                "field": "nested.values"
                            }
                        }
                    }
                }
            }
        }
    }
}

6-result.yaml

{
    "took": 19,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": null,
        "hits": []
    },
    "aggregations": {
        "root": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
                {
                    "key": "1",
                    "doc_count": 1,
                    "values": {
                        "doc_count": 1,
                        "combined": {
                            "doc_count_error_upper_bound": 0,
                            "sum_other_doc_count": 0,
                            "buckets": [
                                {
                                    "key": "1",
                                    "doc_count": 1
                                },
                                {
                                    "key": "2",
                                    "doc_count": 1
                                }
                            ]
                        }
                    }
                },
                {
                    "key": "2",
                    "doc_count": 1,
                    "values": {
                        "doc_count": 1,
                        "combined": {
                            "doc_count_error_upper_bound": 0,
                            "sum_other_doc_count": 0,
                            "buckets": [
                                {
                                    "key": "1",
                                    "doc_count": 1
                                },
                                {
                                    "key": "3",
                                    "doc_count": 1
                                }
                            ]
                        }
                    }
                }
            ]
        }
    }
}