4.高级查询介绍 ES中提供了一种强大的检索数据方式,这种检索方式称之为Query DSL <Domain Specif

介绍

ES中提供了一种强大的检索数据方式,这种检索方式称之为Query DSL <Domain Specified Language> Query DSL是利用Rest API传递JSON格式的请求体(RequestBody)数据与ES进行交互，这种方式的丰富查询语法让Es检索变得更强大，更简洁。

语法

查询所有[match_all]

匹配所有查询 |Elasticsearch 指南 [8.10] |弹性的

# GET /索引/_search {json}

测试

# query DSL 语法 查询所有 match_all
GET /products/_search
{
  "query":{
    "match_all":{"boost": 1}
  }
}

输出结果

{
  "took": 0,   # 花费时间，单位ms
  "timed_out": false,   # 是否超时
  "_shards": {    # 分片信息
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {    # 命中
    "total": {    # 命中总数
      "value": 3,
      "relation": "eq"
    },
    "max_score": 1,    # 得分
    "hits": [    # 真正的文档信息
      {
        "_index": "products",
        "_id": "1",
        "_score": 1,
        "_source": {
          "id": 1,
          "title": "我是cfddfc",
          "price": 1,
          "created_at": "2012-11-12",
          "description": "小老鼠真好吃"
        }
      },
      {
        "_index": "products",
        "_id": "4",
        "_score": 1,
        "_source": {
          "id": 4,
          "title": "好吃的薯片",
          "price": 100,
          "created_at": "2012-11-12",
          "description": "薯片真香！"
        }
      },
      {
        "_index": "products",
        "_id": "3",
        "_score": 1,
        "_source": {
          "id": 3,
          "title": "与馒头",
          "price": 0.5,
          "created_at": "2012-11-12",
          "description": "馒头太好吃了吧"
        }
      }
    ]
  }
}

关键词查询[term]

trem：使用关键词查询

在 ES 中除了 text 类型分词，其余类型均不分词

在 ES 中默认使用标准分词器中文单字分词英文单词分词

分词就是查询的依据，如果查询 value 出现某个分词，就会返回该查询不分词说明，查询这个键是否匹配，必须要完全匹配。

# term 基于关键词查询 
GET /products/_mapping
# keyword 类型 日后搜索使用 全部内容搜索
# text 类型 默认 es 标准分词器 中文单字分词 英文单词分词
# keyword integer double date 不分词
GET /products/_search
{
  "query": {
    "term": {
      "id": {
        "value": 1
      }
    }
  }
}

范围查询[ranger]

range关键字:用来指定查询指定范围内的文档

# 范围查询 ranger
GET /products/_search
{
  "query": {
    "range": {
      "price": {
        "gte": 1,
        "lte": 20
      }
    }
  }
}

前缀查询[prefix]

prefix 关键字：用来检索含有指定前缀的关键词的相关文档

# 前缀查询
GET /products/_search
{
  "query": {
    "prefix": {
      "description": {
        "value": "小老鼠"
      }
    }
  }
}

GET /products/_search
{
  "query": {
    "prefix": {
      "description": {
        "value": "小"
      }
    }
  }
}

因为中文默认分词器是一个字一个字，所以查询不到，结果为空

# pre
{
  "took": 0,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 0,
      "relation": "eq"
    },
    "max_score": null,
    "hits": []
  }
}
# suf
{
  "took": 0,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 1,
    "hits": [
      {
        "_index": "products",
        "_id": "1",
        "_score": 1,
        "_source": {
          "id": 1,
          "title": "我是cfddfc",
          "price": 1,
          "created_at": "2012-11-12",
          "description": "小老鼠真好吃"
        }
      }
    ]
  }
}

通配符查询[wildcard]

wildcard关键字:通配符查询 ? 用来匹配一个任意字符 * 用来匹配多个任意字符

# 通配符查询 * 多个 ? 一个
GET /products/_search
{
  "query": {
    "wildcard": {
      "description": {
        "value": "小*"
      }
    }
  }
}

多id查询[ids]

ids关键字:值为数组类型,用来根据一组id获取多个对应的文档

# 多id查询 查询一组符合条件的id
GET /products/_search
{
  "query": {
    "ids": {
      "values": [3,4,2]
    }
  }
}

模糊查询[fuzzy]

fuzzy关键字:用来模糊查询含有指定关键字的文档

# fuzzy 模糊查询
GET /products/_search
{
  "query": {
    "fuzzy": {
      "title": "鱼馒头"
    }
  }
}

结果

{
  "took": 0,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 0.65388614,
    "hits": [
      {
        "_index": "products",
        "_id": "3",
        "_score": 0.65388614,
        "_source": {
          "id": 3,
          "title": "与馒头",
          "price": 0.5,
          "created_at": "2012-11-12",
          "description": "馒头太好吃了吧"
        }
      }
    ]
  }
}

注意:fuzzy模糊查询最大模糊错误必须在 8 - 2 之间搜索关键词长度为 2 不允许存在模糊搜索关键词长度为 3 - 5 允许一次模糊搜索关键词长度大于 5 允许最大 2 模糊

布尔查询[bool]

bool关键字:用来组合多个条件实现复杂查询 must:相当于 && 同时成立 should:相当于 || 成立一个就行 must_not:相当于 ! 不能满足任何一个

# bool 查询
GET /products/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "ids": {
            "values": [1]
          }
        },{
          "term": {
            "title": {
              "value": "我是cfddfc"
            }
          }
        }
      ]
    }
  }
}

多字段查询[multi_match]

# 多字段查询 multi_match
# 注意：query 输入关键词 输入一段文本
GET /products/_search
{
  "query": {
    "multi_match": {
      "query": "老鼠馒头",
      "fields": ["title","description"]
    }
  }
}

注意：字段类型分词，将查询条件分词之后进行查询改字段如果该字段不分词就会将查询条件作为整体进行查询

{
  "took": 1,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 2,
      "relation": "eq"
    },
    "max_score": 1.9155619,
    "hits": [
      {
        "_index": "products",
        "_id": "1",
        "_score": 1.9155619,
        "_source": {
          "id": 1,
          "title": "我是cfddfc",
          "price": 1,
          "created_at": "2012-11-12",
          "description": "小老鼠真好吃"
        }
      },
      {
        "_index": "products",
        "_id": "3",
        "_score": 1.7894151,
        "_source": {
          "id": 3,
          "title": "与馒头",
          "price": 0.5,
          "created_at": "2012-11-12",
          "description": "馒头太好吃了吧"
        }
      }
    ]
  }
}

默认字段分词查询[query_string]

注意：查询字段分词就将查询条件分词查询查询字段不分词将查询条件不分词查询

# query_string
GET /products/_search
{
  "query": {
    "query_string": {
      "default_field": "description",
      "query": "小老鼠的的"
    }
  }
}

高亮查询[highlight]

highlight关键字：可以让符合条件的文档中的关键词高亮

# query_string
GET /products/_search
{
  "query": {
    "query_string": {
      "default_field": "description",
      "query": "小老鼠的的"
    }
  },
  "highlight": {
    "fields": {
      "description":{}
    }
  }
}

默认<em>标签可以显示高亮，需要前端上面再修改一下，作为特殊的样式自定义

# query_string
GET /products/_search
{
  "query": {
    "query_string": {
      "default_field": "description",
      "query": "小老鼠的的"
    }
  },
  "highlight": {
    "pre_tags": ["<span style='color:red;'>"],
    "post_tags": ["</span>"], 
    "require_field_match": "false", 
    "fields": {
      "description":{}
    }
  }
}

并没有修改文档，而是在输出时加上这些样式

{
  "took": 64,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 2.873343,
    "hits": [
      {
        "_index": "products",
        "_id": "1",
        "_score": 2.873343,
        "_source": {
          "id": 1,
          "title": "我是cfddfc",
          "price": 1,
          "created_at": "2012-11-12",
          "description": "小老鼠真好吃"
        },
        "highlight": {
          "description": [
            "<em>小</em><em>老</em><em>鼠</em>真好吃"
          ]
        }
      }
    ]
  }
}

指定字段排序[sort]

排序之后，每个文档都没有的得分，因为排序干扰了es默认的计分规则

# query_string
GET /products/_search
{
  "query": {
    "query_string": {
      "default_field": "description",
      "query": "*"
    }
  },
  "highlight": {
    "pre_tags": ["<span style='color:red;'>"],
    "post_tags": ["</span>"], 
    "require_field_match": "false", 
    "fields": {
      "description":{}
    }
  },
  "sort":[
    {
      "price":"desc"
    }
  ]
}

返回指定字段[_source]

_source关键字:是一个数组,在数组中用来指定展示那些字段

"_source": ["id","title","description"]