原英文版地址: https://www.elastic.co/guide/en/elasticsearch/reference/7.7/search-aggregations-bucket-children-aggregation.html, 原文档版权归 www.elastic.co 所有
本地英文版地址: ../en/search-aggregations-bucket-children-aggregation.html
本地英文版地址: ../en/search-aggregations-bucket-children-aggregation.html
重要: 此版本不会发布额外的bug修复或文档更新。最新信息请参考 当前版本文档。
一种特殊的单桶聚合，它选择具有指定类型的子文档，如 join字段中定义的那样。
这个聚合只有一个选项：
-
type- 应该选择的子类型。
例如，假设我们有一个问答索引。答案的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 tag 字段，answer 文档包含 owner 字段。
使用 children 聚合，即使两个字段存在于两种不同类型的文档中，也可以在单个请求中将 tag 桶映射到 owner 桶。
question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"
}
可以构建以下请求，将两者连接在一起：
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
}
}
}
}
}
}
}
}
上面的例子返回前几个问题标签和每个标签前几个答案的所有者。
响应可能是：
{
"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
}
]
}
}
}
]
}
}
}