5.2.3. 子聚合

7.3

7.3

子聚合

一种特殊的单存储桶聚合，用于选择具有指定类型的子文档，如join字段。

该聚合只有一个选项：

• type-应选择的子类型。

例如，假设我们有一个问题和答案的索引。答案类型在映射中具有以下join字段：

PUT child_example
{
  "mappings": {
    "properties": {
      "join": {
        "type": "join",
        "relations": {
          "question": "answer"
        }
      }
    }
  }
}

question文档包含一个标记字段，而answer文档包含一个所有者字段。使用子级聚合，即使两个字段存在两种不同的文档中，也可以在单个请求中将标签存储桶映射到所有者存储桶。

问题文档的示例:

PUT child_example/_doc/1
{
  "join": {
    "name": "question"
  },
  "body": "<p>I have Windows 2003 server and i bought a new Windows 2008 server...",
  "title": "Whats the best way to file transfer my site from server to a newer one?",
  "tags": [
    "windows-server-2003",
    "windows-server-2008",
    "file-transfer"
  ]
}

answer文档的示例：

PUT child_example/_doc/2?routing=1
{
  "join": {
    "name": "answer",
    "parent": "1"
  },
  "owner": {
    "location": "Norfolk, United Kingdom",
    "display_name": "Sam",
    "id": 48
  },
  "body": "<p>Unfortunately you're pretty much limited to FTP...",
  "creation_date": "2009-05-04T13:45:37.030"
}

PUT child_example/_doc/3?routing=1&refresh
{
  "join": {
    "name": "answer",
    "parent": "1"
  },
  "owner": {
    "location": "Norfolk, United Kingdom",
    "display_name": "Troll",
    "id": 49
  },
  "body": "<p>Use Linux...",
  "creation_date": "2009-05-05T13:45:37.030"
}

可以建立以下将两者连接在一起的请求：

POST child_example/_search?size=0
{
  "aggs": {
    "top-tags": {
      "terms": {
        "field": "tags.keyword",
        "size": 10
      },
      "aggs": {
        "to-answers": {
          "children": {
            "type" : "answer" 
          },
          "aggs": {
            "top-names": {
              "terms": {
                "field": "owner.display_name.keyword",
                "size": 10
              }
            }
          }
        }
      }
    }
  }
}

1. type指向名称为answer的类型/映射。

上面的示例返回顶部的问题标签，每个标签返回顶部的答案所有者。

可能的响应：

{
  "took": 25,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped" : 0,
    "failed": 0
  },
  "hits": {
    "total" : {
      "value": 3,
      "relation": "eq"
    },
    "max_score": null,
    "hits": []
  },
  "aggregations": {
    "top-tags": {
      "doc_count_error_upper_bound": 0,
      "sum_other_doc_count": 0,
      "buckets": [
        {
          "key": "file-transfer",
          "doc_count": 1, 
          "to-answers": {
            "doc_count": 2, 
            "top-names": {
              "doc_count_error_upper_bound": 0,
              "sum_other_doc_count": 0,
              "buckets": [
                {
                  "key": "Sam",
                  "doc_count": 1
                },
                {
                  "key": "Troll",
                  "doc_count": 1
                }
              ]
            }
          }
        },
        {
          "key": "windows-server-2003",
          "doc_count": 1, 
          "to-answers": {
            "doc_count": 2, 
            "top-names": {
              "doc_count_error_upper_bound": 0,
              "sum_other_doc_count": 0,
              "buckets": [
                {
                  "key": "Sam",
                  "doc_count": 1
                },
                {
                  "key": "Troll",
                  "doc_count": 1
                }
              ]
            }
          }
        },
        {
          "key": "windows-server-2008",
          "doc_count": 1, 
          "to-answers": {
            "doc_count": 2, 
            "top-names": {
              "doc_count_error_upper_bound": 0,
              "sum_other_doc_count": 0,
              "buckets": [
                {
                  "key": "Sam",
                  "doc_count": 1
                },
                {
                  "key": "Troll",
                  "doc_count": 1
                }
              ]
            }
          }
        }
      ]
    }
  }
}

1.标签为file-transfer，windows-server-2003等的问题文档的数量。

2.与标记为file-transfer，windows-server-2003等的问题文档相关的回答文档的数量。

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原文地址：https://learnku.com/docs/elasticsearch73...

译文地址：https://learnku.com/docs/elasticsearch73...