Elasticsearch只有一条记录是基于userid的？

Question

在post索引中，postid是主键，userid是外键。

我想要所有 post 但只有 post 来自一个用户 ID，这样只有一个用户在结果中有一个 post 按 post 日期排序（可选最新第一）

//Actual Result
[
    {
        userid: "u1",
        postid: "p1"
    },
    {
        userid: "u1",
        postid: "p2"
    },
    {
        userid: "u2",
        postid: "p3"
    },
    {
        userid: "u3",
        postid: "p4"
    },
    {
        userid: "u3",
        postid: "p5"
    },
    {
        userid: "u3",
        postid: "p6"
    }
]

需要如下

//Expecting Result
[
    {
        userid: "u1",
        postid: "p1"
    },
    {
        userid: "u2",
        postid: "p3"
    },
    {
        userid: "u3",
        postid: "p4"
    }
]

Answer 1

假设索引映射的形式为：

PUT user_posts
{
  "mappings": {
    "properties": {
      "userid": {
        "type": "keyword"
      },
      "postid": {
        "type": "keyword"
      },
      "postdate": {
        "type": "date"
      }
    }
  }
}

你可以：

聚合 userid 并按字母顺序排列 ID
在 postid 上进行子聚合，并通过 max aggregation.

posttime

通过 filter_path 选项过滤响应以仅检索您需要的内容

POST user_posts/_search?filter_path=aggregations.*.buckets.key,aggregations.*.buckets.*.buckets.key
{
  "size": 0,
  "aggs": {
    "by_userid": {
      "terms": {
        "field": "userid",
        "order": {
          "_key": "asc"
        }, 
        "size": 100
      },
      "aggs": {
        "by_latest_postid": {
          "terms": {
            "field": "postid",
            "size": 1,
            "order": {
              "latest_posttime": "desc"
            }
          },
          "aggs": {
            "latest_posttime": {
              "max": {
                "field": "postdate"
              }
            }
          }
        }
      }
    }
  }
}

产量：

{
  "aggregations" : {
    "by_userid" : {
      "buckets" : [
        {
          "key" : "u1",
          "by_latest_postid" : {
            "buckets" : [
              {
                "key" : "p1"
              }
            ]
          }
        },
        {
          "key" : "u2",
          "by_latest_postid" : {
            "buckets" : [
              {
                "key" : "p3"
              }
            ]
          }
        },
        {
          "key" : "u3",
          "by_latest_postid" : {
            "buckets" : [
              {
                "key" : "p4"
              }
            ]
          }
        }
      ]
    }
  }
}

然后您可以像往常一样post-处理：

...
const response = await ...; // transform the above request for use in the ES JS lib of your choice

const result = response.aggregations.by_userid.buckets.map(b => {
    return {
        userid: b.key,
        postid: b.by_latest_postid.buckets && b.by_latest_postid.buckets[0].key
    }
})

Answer 2

您可以使用 top hits 子聚合。因此，首先按 userId 进行 terms 聚合，然后您可以使用按 post-date 排序的热门点击来获得每个用户的最新 post。

我应该说，如果你有很多 userId 并且你希望每个都获得最高命中率，你应该使用 composite aggregation 作为你的顶级聚合，而不是条款。

Answer 3

我想你可以为此使用热门。这是此示例：

DELETE my-index-000001

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "userid": {
        "type": "keyword"
      },
      "postid": {
        "type": "keyword"
      },
      "postdate": {
        "type": "date"
      }
    }
  }
}

PUT my-index-000001/_doc/1
{"userid": "u1", "postid": "p1", "postdate": "2021-03-01"}

PUT my-index-000001/_doc/2
{"userid": "u1", "postid": "p2", "postdate": "2021-03-02"}

PUT my-index-000001/_doc/3
{"userid": "u2", "postid": "p3", "postdate": "2021-03-03"}

PUT my-index-000001/_doc/4
{"userid": "u3", "postid": "p4", "postdate": "2021-03-04"}

PUT my-index-000001/_doc/5
{"userid": "u3", "postid": "p5", "postdate": "2021-03-05"}

PUT my-index-000001/_doc/6
{"userid": "u3", "postid": "p6", "postdate": "2021-03-06"}

这些是示例索引创建步骤。在这里查询：

GET my-index-000001/_search
{
  "size": 0,
  "aggs": {
    "top_users": {
      "terms": {
        "field": "userid",
        "size": 100
      },
      "aggs": {
        "top": {
          "top_hits": {
            "sort": [
              {
                "postdate": {
                  "order": "desc"
                }
              }
            ],
            "_source": {
              "includes": [ "postdate", "postid" ]
            },
            "size": 1
          }
        }
      }
    }
  }
}

并且，在结果集中，您可以看到聚合中每个用户的顶部 post：

{
  "took" : 3,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 6,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "top_users" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "u3",
          "doc_count" : 3,
          "top" : {
            "hits" : {
              "total" : {
                "value" : 3,
                "relation" : "eq"
              },
              "max_score" : null,
              "hits" : [
                {
                  "_index" : "my-index-000001",
                  "_type" : "_doc",
                  "_id" : "6",
                  "_score" : null,
                  "_source" : {
                    "postdate" : "2021-03-06",
                    "postid" : "p6"
                  },
                  "sort" : [
                    1614988800000
                  ]
                }
              ]
            }
          }
        },
        {
          "key" : "u1",
          "doc_count" : 2,
          "top" : {
            "hits" : {
              "total" : {
                "value" : 2,
                "relation" : "eq"
              },
              "max_score" : null,
              "hits" : [
                {
                  "_index" : "my-index-000001",
                  "_type" : "_doc",
                  "_id" : "2",
                  "_score" : null,
                  "_source" : {
                    "postdate" : "2021-03-02",
                    "postid" : "p2"
                  },
                  "sort" : [
                    1614643200000
                  ]
                }
              ]
            }
          }
        },
        {
          "key" : "u2",
          "doc_count" : 1,
          "top" : {
            "hits" : {
              "total" : {
                "value" : 1,
                "relation" : "eq"
              },
              "max_score" : null,
              "hits" : [
                {
                  "_index" : "my-index-000001",
                  "_type" : "_doc",
                  "_id" : "3",
                  "_score" : null,
                  "_source" : {
                    "postdate" : "2021-03-03",
                    "postid" : "p3"
                  },
                  "sort" : [
                    1614729600000
                  ]
                }
              ]
            }
          }
        }
      ]
    }
  }
}

Elasticsearch只有一条记录是基于userid的？

Elasticsearch only one record based on userid?

javascript

elasticsearch

elasticsearch-7