如何根据elasticsearch中存储的字段值获取前5个文档？

Question

示例 - 学生的一个科目的考试成绩存储在弹性搜索索引中。 现在我想找到该科目得分最高的前 5 名学生。

Answer 1

让我通过使用示例来展示它，但首先要了解这个概念。

根据给定的题目第一个查询，在我的例子著名math学科:)，然后将获取所有的学生，有math学科，是经过sort的desc顺序基于他们的score ，然后size PARAM限制的结果顶部k学生.

与答案相关的 Imp 链接：

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

创建索引

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

索引一些文档

{
   "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
}

搜索查询以搜索subject并根据分数对结果进行排序并返回前 3 名学生。

{
    "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.
}

搜索查询结果

{
            "_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对搜索结果进行排序，即score
该文档可以帮助您https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-request-sort.html