Children Aggregation

原文链接 : https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-children-aggregation.html

译文链接 : http://www.apache.wiki/display/Elasticsearch（修改该链接为 ApacheCN 对应的译文链接）

贡献者 : @于永超，ApacheCN，Apache中文网

一种特殊的单桶聚合，可以将父文档类型上的桶聚合到子文档上。

此聚合依赖于映射中的_parent字段。 此聚合有一个选项：

  • type - 应该映射到父空间中的子类型的buckets(桶)

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_parent字段

  1. PUT child_example
  2. {
  3.     "mappings": {
  4.         "answer" : {
  5.             "_parent" : {
  6.                 "type" : "question"
  7.             }
  8.         }
  9.     }
  10. }

问题类型的文档包含标签字段，答案类型的文档包含所有者字段。 使用子集合，即使两个字段存在于两种不同类型的文档中，标记桶也可以在单个请求中映射到所有者桶。

一个问题类型文档的例子

  1. PUT child_example/question/1
  2. {
  3.     "body": "<p>I have Windows 2003 server and i bought a new Windows 2008 server...",
  4.     "title": "Whats the best way to file transfer my site from server to a newer one?",
  5.     "tags": [
  6.         "windows-server-2003",
  7.         "windows-server-2008",
  8.         "file-transfer"
  9.     ]
  10. }

回答类型文件的例子:

  1. PUT child_example/answer/1?parent=1&refresh
  2. {
  3.     "owner": {
  4.         "location": "Norfolk, United Kingdom",
  5.         "display_name": "Sam",
  6.         "id": 48
  7.     },
  8.     "body": "<p>Unfortunately you're pretty much limited to FTP...",
  9.     "creation_date": "2009-05-04T13:45:37.030"
  10. }
  11. PUT child_example/answer/2?parent=1&refresh
  12. {
  13.     "owner": {
  14.         "location": "Norfolk, United Kingdom",
  15.         "display_name": "Troll",
  16.         "id": 49
  17.     },
  18.     "body": "<p>Use Linux...",
  19.     "creation_date": "2009-05-05T13:45:37.030"
  20. }

可以构建将两者连接在一起的以下请求：

  1. POST child_example/_search?size=0
  2. {
  3.   "aggs": {
  4.     "top-tags": {
  5.       "terms": {
  6.         "field": "tags.keyword",
  7.         "size": 10
  8.       },
  9.       "aggs": {
  10.         "to-answers": {
  11.           "children": {
  12.             "type" : "answer"  ＃1
  13.           },
  14.           "aggs": {
  15.             "top-names": {
  16.               "terms": {
  17.                 "field": "owner.display_name.keyword",
  18.                 "size": 10
  19.               }
  20.             }
  21.           }
  22.         }
  23.       }
  24.     }
  25.   }
  26. }

＃1 type 指向使用名称为answer的 type / mapping

以上示例返回顶级问题标签和每个标签的顶级答案所有者。

下面是可能的返回结果：

  1. {
  2.   "timed_out": false,
  3.   "took": 25,
  4.   "_shards": { "total": 5, "successful": 5, "failed": 0 },
  5.   "hits": { "total": 3, "max_score": 0.0, hits: [] },
  6.   "aggregations": {
  7.     "top-tags": {
  8.       "doc_count_error_upper_bound": 0,
  9.       "sum_other_doc_count": 0,
  10.       "buckets": [
  11.         {
  12.           "key": "file-transfer",
  13.           "doc_count": 1, ＃1
  14.           "to-answers": {
  15.             "doc_count": 2, ＃2
  16.             "top-names": {
  17.               "doc_count_error_upper_bound": 0,
  18.               "sum_other_doc_count": 0,
  19.               "buckets": [
  20.                 {
  21.                   "key": "Sam",
  22.                   "doc_count": 1
  23.                 },
  24.                 {
  25.                   "key": "Troll",
  26.                   "doc_count": 1
  27.                 }
  28.               ]
  29.             }
  30.           }
  31.         },
  32.         {
  33.           "key": "windows-server-2003",
  34.           "doc_count": 1, ＃3
  35.           "to-answers": {
  36.             "doc_count": 2, ＃4
  37.             "top-names": {
  38.               "doc_count_error_upper_bound": 0,
  39.               "sum_other_doc_count": 0,
  40.               "buckets": [
  41.                 {
  42.                   "key": "Sam",
  43.                   "doc_count": 1
  44.                 },
  45.                 {
  46.                   "key": "Troll",
  47.                   "doc_count": 1
  48.                 }
  49.               ]
  50.             }
  51.           }
  52.         },
  53.         {
  54.           "key": "windows-server-2008",
  55.           "doc_count": 1, ＃5
  56.           "to-answers": {
  57.             "doc_count": 2, ＃6
  58.             "top-names": {
  59.               "doc_count_error_upper_bound": 0,
  60.               "sum_other_doc_count": 0,
  61.               "buckets": [
  62.                 {
  63.                   "key": "Sam",
  64.                   "doc_count": 1
  65.                 },
  66.                 {
  67.                   "key": "Troll",
  68.                   "doc_count": 1
  69.                 }
  70.               ]
  71.             }
  72.           }
  73.         }
  74.       ]
  75.     }
  76.   }
  77. }

＃1 带有file-transfer，windows-server-2003等标签问题文档数量

＃3

＃5

＃2 带有file-transfer, windows-server-2003等标签的与问题文档相关的答复文档的数量

＃4

＃6