如何根據elasticsearch中存儲的字段值獲取前5個文檔？

Question

示例 - 學生的一個科目的考試成績存儲在彈性搜索索引中。 現在我想找到該科目得分最高的前 5 名學生。

Answer 1

讓我通過使用示例來展示它，但首先要了解這個概念。

根據給定的題目第一個查詢，在我的例子著名math學科:)，然后將獲取所有的學生，有math學科，是經過sort的desc順序基於他們的score ，然后size PARAM限制的結果頂部k學生.

與答案相關的 Imp 鏈接：

https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-request-from-size.html

https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-term-query.html

https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-request-sort.html

創建索引

{
    "mappings": {
        "properties": {
            "sid": {
                "type": "integer"
            },
            "subject" :{
                "type" : "keyword"
            },
            "score" :{
                "type" : "integer"
            }
        }
    }
}

索引一些文檔

{
   "sid" : 1,
   "subject" :"math",
   "score" : 50
}

{
   "sid" : 2,
   "subject" :"math",
   "score" : 60
}
{
   "sid" : 3,
   "subject" :"math",
   "score" : 70
}
{
   "sid" : 4,
   "subject" :"math",
   "score" : 90
}
{
   "sid" : 5,
   "subject" :"math",
   "score" : 99
}

{
   "sid" : 6,
   "subject" :"math",
   "score" : 100
}

搜索查詢以搜索subject並根據分數對結果進行排序並返回前 3 名學生。

{
    "sort": [
        {
            "score": {
                "order": "desc" --> define sort order
            }
        }
    ],
    "query": {
        "term": {
            "subject": "math"
        }
    },
    "size":3 -->important, you can change it to fetch top K students, Just change 3 to whatever no you want to fetch.
}

搜索查詢結果

{
            "_index": "leaderboard",
            "_type": "_doc",
            "_id": "5",
            "_score": null,
            "_source": {
               "sid": 6,
               "subject": "math",
               "score": 100
            },
            "sort": [
               100
            ]
         },
         {
            "_index": "leaderboard",
            "_type": "_doc",
            "_id": "4",
            "_score": null,
            "_source": {
               "sid": 4,
               "subject": "math",
               "score": 90
            },
            "sort": [
               90
            ]
         },
         {
            "_index": "leaderboard",
            "_type": "_doc",
            "_id": "3",
            "_score": null,
            "_source": {
               "sid": 3,
               "subject": "math",
               "score": 70
            },
            "sort": [
               70
            ]
         }

Answer 2

只需按您想要的字段對搜索結果進行排序，即score
該文檔可以幫助您https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-request-sort.html