反向嵌套聚合
编辑反向嵌套聚合
编辑一种特殊的单桶聚合，允许对嵌套文档的父文档进行聚合。 实际上，这种聚合可以突破嵌套块结构，并链接到其他嵌套结构或根文档，从而允许嵌套不属于嵌套聚合中嵌套对象的其他聚合。
reverse_nested 聚合必须在 nested 聚合内定义。
选项
-
path- 定义应该连接回哪个嵌套对象字段。 默认值为空，这意味着它连接回根/主文档级别。 该路径不能包含对nested聚合嵌套结构之外的嵌套对象字段的引用，reverse_nested位于其中。
例如，假设我们有一个包含问题和评论的票务系统的索引。 评论以嵌套文档的形式内联到问题文档中。 映射可能如下所示
resp = client.indices.create(
index="issues",
mappings={
"properties": {
"tags": {
"type": "keyword"
},
"comments": {
"type": "nested",
"properties": {
"username": {
"type": "keyword"
},
"comment": {
"type": "text"
}
}
}
}
},
)
print(resp)
response = client.indices.create(
index: 'issues',
body: {
mappings: {
properties: {
tags: {
type: 'keyword'
},
comments: {
type: 'nested',
properties: {
username: {
type: 'keyword'
},
comment: {
type: 'text'
}
}
}
}
}
}
)
puts response
const response = await client.indices.create({
index: "issues",
mappings: {
properties: {
tags: {
type: "keyword",
},
comments: {
type: "nested",
properties: {
username: {
type: "keyword",
},
comment: {
type: "text",
},
},
},
},
},
});
console.log(response);
PUT /issues
{
"mappings": {
"properties": {
"tags": { "type": "keyword" },
"comments": {
"type": "nested",
"properties": {
"username": { "type": "keyword" },
"comment": { "type": "text" }
}
}
}
}
}
以下聚合将返回已评论的顶级评论者的用户名，以及每个顶级评论者评论的问题的顶级标签
resp = client.search(
index="issues",
query={
"match_all": {}
},
aggs={
"comments": {
"nested": {
"path": "comments"
},
"aggs": {
"top_usernames": {
"terms": {
"field": "comments.username"
},
"aggs": {
"comment_to_issue": {
"reverse_nested": {},
"aggs": {
"top_tags_per_comment": {
"terms": {
"field": "tags"
}
}
}
}
}
}
}
}
},
)
print(resp)
response = client.search(
index: 'issues',
body: {
query: {
match_all: {}
},
aggregations: {
comments: {
nested: {
path: 'comments'
},
aggregations: {
top_usernames: {
terms: {
field: 'comments.username'
},
aggregations: {
comment_to_issue: {
reverse_nested: {},
aggregations: {
top_tags_per_comment: {
terms: {
field: 'tags'
}
}
}
}
}
}
}
}
}
}
)
puts response
const response = await client.search({
index: "issues",
query: {
match_all: {},
},
aggs: {
comments: {
nested: {
path: "comments",
},
aggs: {
top_usernames: {
terms: {
field: "comments.username",
},
aggs: {
comment_to_issue: {
reverse_nested: {},
aggs: {
top_tags_per_comment: {
terms: {
field: "tags",
},
},
},
},
},
},
},
},
},
});
console.log(response);
GET /issues/_search
{
"query": {
"match_all": {}
},
"aggs": {
"comments": {
"nested": {
"path": "comments"
},
"aggs": {
"top_usernames": {
"terms": {
"field": "comments.username"
},
"aggs": {
"comment_to_issue": {
"reverse_nested": {},
"aggs": {
"top_tags_per_comment": {
"terms": {
"field": "tags"
}
}
}
}
}
}
}
}
}
}
如上所示，reverse_nested 聚合被放入 nested 聚合中，因为这是 DSL 中唯一可以使用 reverse_nested 聚合的地方。 它唯一目的是连接回嵌套结构中更上层的父文档。
|
由于没有定义 |
可能的响应片段
{
"aggregations": {
"comments": {
"doc_count": 1,
"top_usernames": {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets": [
{
"key": "username_1",
"doc_count": 1,
"comment_to_issue": {
"doc_count": 1,
"top_tags_per_comment": {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets": [
{
"key": "tag_1",
"doc_count": 1
}
...
]
}
}
}
...
]
}
}
}
}