elasticsearch - 如何使用Elastic对嵌套对象进行子聚合？

Question

我有以下架构来表示可以具有多种变体的产品(例如:T恤的尺寸):

{
    "mappings": {
        "properties": {
            "id": {"type": "keyword"},
            "name": {"type": "text"},
            "variants": {
                "type": "nested",
                "properties": {
                    "inventory": {"type": "long"},
                    "customizations": {"type": "object"},
                    "customizations.name": {"type": "keyword"},
                    "customizations.value": {"type": "keyword"}
                }
            }
        }
    }
}

然后，我可以使用它插入如下所示的产品数据:

{
    "id": "prod-1",
    "name": "Shirt Design 1",
    "variants": [
        {"inventory": 78, "customizations": [{"name": "size", "value": "L"}, {"name": "color", "value": "blue"}]},
        {"inventory": 78, "customizations": [{"name": "size", "value": "M"}, {"name": "color", "value": "blue"}]},
        {"inventory": 89, "customizations": [{"name": "size", "value": "S"}, {"name": "color", "value": "blue"}]}
    ]
}
{
    "id": "prod-2",
    "name": "Shirt Design 2",
    "variants": [
        {"inventory": 78, "customizations": [{"name": "size", "value": "L"}, {"name": "color", "value": "green"}]},
        {"inventory": 78, "customizations": [{"name": "size", "value": "M"}, {"name": "color", "value": "green"}]}
    ]
}

筛选/查询此索引时，我希望能够根据构成产品的自定义来显示构面。这些自定义项是用户提交的，因此不在我的控制范围内，但其想法是能够显示以下过滤器:

☐ Size:
    - S (1)
    - M (2)
    - L (2)
☐ Color:
    - blue (1)
    - green (1)

现在，我可以使用以下查询按自定义名称正确存储分区:

{
    "size": 0,
    "aggs": {
        "skus": {
            "nested": {
                "path": "variants"
            },
            "aggs": {
                "customization_names": {
                    "terms": {
                        "field": "variants.customizations.name"
                    }
                }
            }
        }
    }
}

这给了我以下几个方面:

"buckets": [
        {
            "doc_count": 2,
            "key": "color"
        },
        {
            "doc_count": 2,
            "key": "size"
        }
    ],

试图进行子聚合以获取下面的实际自定义列表是我遇到的困难。我试过了:

{
    "size": 0,
    "aggs": {
        "skus": {
            "nested": {
                "path": "variants"
            },
            "aggs": {
                "customization_names": {
                    "terms": {
                        "field": "variants.customizations.name"
                    },
                    "aggs": {
                        "sub": {
                            "reverse_nested": {},
                            "aggs": {
                                "customization_values": {
                                    "terms": {
                                        "field": "variants.customizations.value"
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

不返回任何子桶:

buckets": [
                    {
                        "doc_count": 4,
                        "key": "color",
                        "sub": {
                            "doc_count": 2,
                            "customization_values": {
                                "buckets": [],
                                "doc_count_error_upper_bound": 0,
                                "sum_other_doc_count": 0
                            }
                        }
                    },
                    {
                        "doc_count": 4,
                        "key": "size",
                        "sub": {
                            "doc_count": 2,
                            "customization_values": {
                                "buckets": [],
                                "doc_count_error_upper_bound": 0,
                                "sum_other_doc_count": 0
                            }
                        }
                    }
                ],

如果我不使用 reverse_nested而不是空的子桶，那么我会在其中获得所有可能的值，因此，例如，我将 red and blue作为 size子桶的一部分。
最初，我把 customizations作为key => value的映射，但是也无法使其工作。但是，“自定义”的格式在这里有些可自定义。
到目前为止，我发现解决此问题的唯一方法是在自定义项中添加一个字段，该字段是name + value的json字符串表示形式。

// mapping:
"customizations.facet_code": {"type": "keyword"}
// data:
"customizations": [{"name": "size", "value": "M", "facet_code": "{name:size,value:M}"],

然后，我可以根据 facet_code正确进行存储，并且我的应用程序可以将其反序列化以再次将事物重新组合在一起。
如果能的话，我希望我能弄清楚如何“正确地”做到这一点。

Answer 1

执行此操作的“正确”方法是也将customizations设置为nested类型，而不是object。也就是说:

{
  "mappings": {
    "properties": {
      "id": {
        "type": "keyword"
      },
      "name": {
        "type": "text"
      },
      "variants": {
        "type": "nested",
        "properties": {
          "inventory": {
            "type": "long"
          },
          "customizations": {
            "type": "nested",       <-- This
            "properties": {
              "name": {
                "type": "keyword"
              },
              "value": {
                "type": "keyword"
              }
            }
          }
        }
      }
    }
  }
}

该查询将是

{
  "size": 0,
  "aggs": {
    "skus": {
      "nested": {
        "path": "variants.customizations"
      },
      "aggs": {
        "customization_names": {
          "terms": {
            "field": "variants.customizations.name"
          },
          "aggs": {
            "customization_values": {
              "terms": {
                "field": "variants.customizations.value"
              }
            }
          }
        }
      }
    }
  }
}

产生所有必需的方面:

{
  ...
  "aggregations":{
    "skus":{
      "doc_count":10,
      "customization_names":{
        "doc_count_error_upper_bound":0,
        "sum_other_doc_count":0,
        "buckets":[
          {
            "key":"color",
            "doc_count":5,
            "customization_values":{
              "doc_count_error_upper_bound":0,
              "sum_other_doc_count":0,
              "buckets":[
                {
                  "key":"blue",
                  "doc_count":3
                },
                {
                  "key":"green",
                  "doc_count":2
                }
              ]
            }
          },
          {
            "key":"size",
            "doc_count":5,
            "customization_values":{
              "doc_count_error_upper_bound":0,
              "sum_other_doc_count":0,
              "buckets":[
                {
                  "key":"L",
                  "doc_count":2
                },
                {
                  "key":"M",
                  "doc_count":2
                },
                {
                  "key":"S",
                  "doc_count":1
                }
              ]
            }
          }
        ]
      }
    }
  }
}