Elasticsearch第三篇：查询详解

从第一篇开始，我用的ES版本就是7.8.0的，与低版本略有不同，不同点可以参考官方介绍，最大的不同就是抛弃 type 这一概念，为了方便测试，首先建立一个学生成绩的索引库（在建立的同时，规定字段类型，并指定IK中文分词）

PUT http://localhost:9200/db_student
{
    "mappings": {
            "properties": {
                "class": {
                    "type": "integer",
                    "store": true,
                    "index":true
                },
                "chinese": {
                    "type": "integer",
                    "store": true,
                    "index":true
                },
                "english": {
                    "type": "integer",
                    "store": true,
                    "index":true
                },
                "math": {
                    "type": "integer",
                    "store": true,
                    "index":true
                },
                "name": {
                    "type": "text",
                    "store": true,
                    "index":true
                },
                "school": {
                    "type": "text",
                    "store": true,
                    "index":true,
                    "analyzer":"ik_max_word"
                }
            }
    }
}

为了方便测试，需要先插入测试数据，如下，一共插入8条记录

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Vincent",
"school":"华南理工大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Kitty",
"school":"华南理工大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Thomas",
"school":"华南师范大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Lucy",
"school":"华南师范大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Lily",
"school":"华南农业大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Coco",
"school":"华南农业大学"
}

PUT http://localhost:/db_student/_doc/
{
"chinese":,
"class":,
"english":,
"math":,
"name":"Allen",
"school":"中山大学"
}

PUT http://localhost:/db_student/_doc/
{"chinese":,
"class":,
"english":,
"math":,
"name":"Zack",
"school":"中山大学"
}

打开 Kibana 可以看到已经插入的数据，如下

数据已经插入，现在可以来实现基本的查询了。

1、查询所有索引库、所有文档

POST  http://localhost:9200/_search
{
   "query": {
       "match_all": {}
   }   
}

2、查询索引库 db_student 所有文档

POST  http://localhost:9200/db_student/_search
或者是 http://localhost:9200/db_student/_doc/_search
{
   "query": {
       "match_all": {}
   }
}

3、根据文档编号 id=1 来获取文档

GET  http://localhost:/db_student/_doc/

4、查询 class=10 的学生

注意：term 在这里相当于 = 的逻辑，但是如果是字符串，还可以是包含的逻辑。

POST  http://localhost:/db_student/_search
{
   "query": {
       "bool":{
             "must":[
                   {"term":{"class":}}
             ]
       }
   }
}

5、And 逻辑查询，如查询 class=10 并且 name=vincent 的文档

POST  http://localhost:/db_student/_search
{
  "query": {
     "bool":{
         "must":[
             {"term":{"name":"vincent"}},
             {"term":{"class":}}
         ]
     }
  }
}

6、模糊查询，例如，查询 school 包含 “华南” 的文档

POST  http://localhost:/db_student/_search
{
   "query": {
       "bool":{
             "must":[
                   {"match":{"school":"华南"}}
             ]
       }
   }
}

也可以是term

POST  http://localhost:/db_student/_search
{
   "query": {
       "bool":{
             "must":[
                   {"term":{"school":"华南"}}
             ]
       }
   }
}

7、范围查询，查询 english 大于等于90，小于等于100的文档

注意：from、to 都是闭包的，包含等于

POST   http://localhost:/db_student/_search
{
   "query": {
       "bool":{
             "must":[
                   {"range":{"english":{"from":,"to":}}}
             ]
       }
   }
}

还可以查大于、小于的逻辑，例如查询  english 大于90的文档

注意：gt 表示大于， lt 表示小于 ，这两者都不包含等于

POST http://localhost:/db_student/_search
{
   "query": {
       "bool":{
             "must":[
                   {"range":{"english":{"gt":}}}
             ]
       }
   }
}

8、高亮显示，例如 name 高亮

POST  http://localhost:/db_student/_search
{
   "query": {
      "term":{"name":"vincent"}
   },
   "highlight":{
          "pre_tags" : "<a class='red'>",
          "post_tags" : "</a>",
          "fields" : {
             "name" : {}
        }
   }
}

查询结果是：

{
    "took": ,
    "timed_out": false,
    "_shards": {
        "total": ,
        "successful": ,
        "skipped": ,
        "failed":
    },
    "hits": {
        "total": {
            "value": ,
            "relation": "eq"
        },
        "max_score": .,
        "hits": [
            {
                "_index": "db_student",
                "_type": "_doc",
                "_id": "",
                "_score": .,
                "_source": {
                    "chinese": ,
                    "class": ,
                    "english": ,
                    "math": ,
                    "name": "Vincent",
                    "school": "华南理工大学"
                },
                "highlight": {
                    "name": [
                        "<a class='red'>Vincent</a>"
                    ]
                }
            }
        ]
    }
}

9、分页和排序，先按照 english 倒序，再按 math 升序，每页3条记录，取第一页

POST  http://localhost:/db_student/_search
{
    "query": {
        "match_all":{}
    },
    "from": ,
    "size": ,
    "sort":{
        "english" : {"order" : "desc"},
        "math": {"order" : "asc"}

    }
}

查询结果是

{
    "took": ,
    "timed_out": false,
    "_shards": {
        "total": ,
        "successful": ,
        "skipped": ,
        "failed":
    },
    "hits": {
        "total": {
            "value": ,
            "relation": "eq"
        },
        "max_score": null,
        "hits": [
            {
                "_index": "db_student",
                "_type": "_doc",
                "_id": "",
                "_score": null,
                "_source": {
                    "chinese": ,
                    "class": ,
                    "english": ,
                    "math": ,
                    "name": "Lily",
                    "school": "华南农业大学"
                },
                "sort": [
                    ,

                ]
            },
            {
                "_index": "db_student",
                "_type": "_doc",
                "_id": "",
                "_score": null,
                "_source": {
                    "chinese": ,
                    "class": ,
                    "english": ,
                    "math": ,
                    "name": "Vincent",
                    "school": "华南理工大学"
                },
                "sort": [
                    ,

                ]
            },
            {
                "_index": "db_student",
                "_type": "_doc",
                "_id": "",
                "_score": null,
                "_source": {
                    "chinese": ,
                    "class": ,
                    "english": ,
                    "math": ,
                    "name": "Lucy",
                    "school": "华南师范大学"
                },
                "sort": [
                    ,

                ]
            }
        ]
    }
}

聚合查询、统计查询等等， 稍后补上