elasticsearch - 我应该如何编写查询以仅在Elasticsearch中获取嵌套属性

Question

我的索引如下。

{
    "id": {
        "type": "keyword"
    },
    "title": {
        "type": "text"
    },
    "comments": {
        "type": "nested"
    }
}

我把一些文档如下。

{
    "id": 1,
    "title": "Types",
    "comments": [
        {
            "id": 113,
            "contents": "Number"
        },
        {
            "id": 2005,
            "contents": "String"
        },
        {
            "id": 317,
            "contents": "Boolean"
        }
    ]
}
{
    "id": 2,
    "title": "Animals",
    "comments": [
        {
            "id": 45,
            "contents": "Dog"
        },
        {
            "id": 175,
            "contents": "Cat"
        },
        {
            "id": 26,
            "contents": "Pig"
        }
    ]
}
{
    "id": 3,
    "title": "Colors",
    "comments": [
        {
            "id": 97,
            "contents": "Red"
        },
        {
            "id": 28,
            "contents": "Green"
        },
        {
            "id": 56,
            "contents": "Blue"
        }
    ]
}

当我如下使用嵌套查询时，总数仅为3，但我想得到9(全部有关嵌套属性)。

{
    "query": {
        "nested": {
            "path": "comment",
            "query": {
                "match_all": {}
            }
        }
    }
}

我得到的结果如下。

{
    "hits": {
        "total": 3,
        "hits": [
            {
                "_source": {
                    "id": 1,
                    "title": "Types",
                    "comments": [...]
                }
            },
            {
                "_source": {
                    "id": 2,
                    "title": "Animals",
                    "comments": [...]
                }
            },
            {
                "_source": {
                    "id": 3,
                    "title": "Colors",
                    "comments": [...]
                }
            }
        ]
    }
}

但我希望结果类似于以下格式。

{
    "hits": {
        "total": 9,
        "hits": [
            {
                "_source": {
                    "id": 113,
                    "contents": "Number"
                }
            },
            ...,
            {
                "_source": {
                    "id": 56,
                    "contents": "Blue"
                }
            }
        ]
    }
}

我应该如何编写查询以获取仅9个嵌套属性，如我上面想要的结果？

Answer 1

您需要像这样使用nested inner_hits :

{
    "_source": false,              <-- add this to prevent the parent doc from showing up
    "query": {
        "nested": {
            "path": "comment",
            "query": {
                "match_all": {}
            },
            "inner_hits": {}       <-- and this to only show the matching nested documents
        }
    }
}