Children Aggregation · Elasticsearch 5.4 中文文档

# Children Aggregation 原文链接 : [https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-children-aggregation.html](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](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](/display/~apachecn)，[Apache中文网](/display/~apachechina) 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](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-parent-field.html)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 ``` PUT child_example { "mappings": { "answer" : { "_parent" : { "type" : "question" } } } } ``` 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 ``` PUT child_example/question/1 { "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" ] } ``` 回答类型文件的例子: ``` PUT child_example/answer/1?parent=1&refresh { "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/answer/2?parent=1&refresh { "owner": { "location": "Norfolk, United Kingdom", "display_name": "Troll", "id": 49 }, "body": "<p>Use Linux...", "creation_date": "2009-05-05T13:45:37.030" } ``` 可以构建将两者连接在一起的以下请求： ``` POST child_example/_search?size=0 { "aggs": { "top-tags": { "terms": { "field": "tags.keyword", "size": 10 }, "aggs": { "to-answers": { "children": { "type" : "answer" ＃1 }, "aggs": { "top-names": { "terms": { "field": "owner.display_name.keyword", "size": 10 } } } } } } } } ``` ＃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： ``` { "timed_out": false, "took": 25, "_shards": { "total": 5, "successful": 5, "failed": 0 }, "hits": { "total": 3, "max_score": 0.0, hits: [] }, "aggregations": { "top-tags": { "doc_count_error_upper_bound": 0, "sum_other_doc_count": 0, "buckets": [ { "key": "file-transfer", "doc_count": 1, ＃1 "to-answers": { "doc_count": 2, ＃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, ＃3 "to-answers": { "doc_count": 2, ＃4 "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, ＃5 "to-answers": { "doc_count": 2, ＃6 "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 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