阅读 182

Elasticsearch笔记第五篇

Elasticsearch核心知识篇(7)

这篇主要是针对搜索的多种方式进行讲解,重点注意全文检索短语检索的过程和区别

query string search

搜索全部商品:

GET /ecommerce/product/_search
复制代码
  • took:耗费了几毫秒
  • timed_out:是否超时,这里是没有
  • _shards:数据拆成了5个分片,所以对于搜索请求,会打到所有的primary shard(或者是它的某个replica shard也可以)
  • hits.total:查询结果的数量,3个document
  • hits.max_score:score的含义,就是document对于一个search的相关度的匹配分数,越相关,就越匹配,分数也高
  • hits.hits:包含了匹配搜索的document的详细数据
{
  "took": 9,                # 总共用时9ms
  "timed_out": false,       # 没有超时
  "_shards": {              # 一个请求,在多少个primary shard上进行搜索
    "total": 5,             # 5个,创建的时候默认是生成5个primary shard
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,            # 查询出来满足条件的总document数
    "max_score": 1,        # 最大的相关分数
    "hits": [              # 详细document信息
      {
        "_index": "ecommerce",      # index
        "_type": "product",         # type
        "_id": "2",                 # id
        "_score": 1,                # 相关度分数
        "_source": {                       # document 中的原始数据
          "name": "jiajieshi yagao",          # field 字段
          "desc": "youxiao fangzhu",
          "price": 25,
          "producer": "jiajieshi producer",
          "tags": [
            "fangzhu"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 1,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        }
      }
    ]
  }
}
复制代码

query string search的由来,因为search参数都是以http请求的query string来附带的

搜索商品名称中包含yagao的商品,而且按照售价降序排序:

其实我们去看下面的命令的时候我们会发现其实就是一个GET命令,路由?路径参数(特有:操作选项),请求到服务器后,服务器给你返回一个json串

  • q=name:yagao 名称中带有yagao的document
  • sort=price:desc 价格降序
GET /ecommerce/product/_search?q=name:yagao&sort=price:desc
{
  "took": 26,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": null,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": null,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        },
        "sort": [               # 我们可以看到比上面搜索的时候多了一个字段sort 就是排序字段
          40
        ]
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "2",
        "_score": null,
        "_source": {
          "name": "jiajieshi yagao",
          "desc": "youxiao fangzhu",
          "price": 25,
          "producer": "jiajieshi producer",
          "tags": [
            "fangzhu"
          ]
        },
        "sort": [
          25
        ]
      }
    ]
  }
}
复制代码

适用于临时的在命令行使用一些工具,比如curl,快速的发出请求,来检索想要的信息;但是如果查询请求很复杂,是很难去构建的 在生产环境中,几乎很少使用query string search


query DSL

DSL:Domain Specified Language,特定领域的语言,指的是es中特定的语法

http request body:请求体,可以用json的格式来构建查询语法,比较方便,可以构建各种复杂的语法,比query string search肯定强大多了

总结下:

  • query:match_all/match
  • sort
  • from
  • size
  • _source

查询所有的商品

GET /ecommerce/product/_search
{
  "query": { "match_all": {} }        # query 和上面的q是一样的效果,match_all 匹配所有数据
}

{
  "took": 1,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 1,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "2",
        "_score": 1,
        "_source": {
          "name": "jiajieshi yagao",
          "desc": "youxiao fangzhu",
          "price": 25,
          "producer": "jiajieshi producer",
          "tags": [
            "fangzhu"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 1,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        }
      }
    ]
  }
}
复制代码

查询名称包含yagao的商品,同时按照价格降序排序

GET /ecommerce/product/_search
{
    "query" : {
        "match" : {
            "name" : "yagao"           # match 匹配 name字段中包含xxx  sort 按照xxx字段的升、降序
        }
    },
    "sort": [
        { "price": "desc" }
    ]
}
复制代码

分页查询商品,总共3条商品,假设每页就显示1条商品,现在显示第2页,所以就查出来第2个商品

GET /ecommerce/product/_search
{
  "query": { "match_all": {} },
  "from": 1,    # 就是offset,从那个数据开始查询
  "size": 1     # limit 一页查询多少数据
}

# from 1 size 1 从第一条数据往后在查出来1条数据,就是要查第二条数据 
{
  "took": 1,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 1,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 1,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        }
      }
    ]
  }
}
复制代码

指定要查询出来商品的名称和价格就可以

GET /ecommerce/product/_search
{
  "query": { "match_all": {} },            # _source中指定字段进行输出
  "_source": ["name", "price"]
}

{
  "took": 20,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 1,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "2",
        "_score": 1,
        "_source": {
          "price": 25,
          "name": "jiajieshi yagao"
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 1,
        "_source": {
          "price": 40,
          "name": "zhonghua yagao"
        }
      }
    ]
  }
}
复制代码

更加适合生产环境的使用,可以构建复杂的查询


query filter

搜索商品名称包含yagao,而且售价大于25元的商品

GET /ecommerce/product/_search
{
    "query" : {
        "bool" : {                             # bool封装多个条件
            "must" : {                         # must 必须要满足
                "match" : {
                    "name" : "yagao" 
                }
            },
            "filter" : {                      # filter过滤规则:range范围过滤
                "range" : {
                    "price" : { "gt" : 25 } 
                }
            }
        }
    }
}

{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.25811607,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 0.25811607,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        }
      }
    ]
  }
}
复制代码

full-text search(全文检索)

producer这个字段,会先被拆解,建立倒排索引

  • special 4
  • yagao 4
  • producer 1,2,3,4
  • gaolujie 1
  • zhognhua 3
  • jiajieshi 2

yagao producer ---> yagao和producer 注意这个地方全文匹配的时候是,将字段进行分词后在进行匹配

GET /ecommerce/product/_search
{
    "query" : {
        "match" : {
            "producer" : "yagao producer"
        }
    }
}

{
  "took": 4,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 5,
    "max_score": 0.51623213,        # 我们可以看到匹配到的分数其实是不一样的
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "1",
        "_score": 0.51623213,
        "_source": {
          "name": "jiaqiangban gaolujie yagao",
          "desc": "gaoxiao meibai",
          "price": 30,
          "producer": "yagao producer",
          "tags": [
            "meibai",
            "fangzhu"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "5",
        "_score": 0.25811607,
        "_source": {
          "name": "waws520 yagao",
          "desc": "caoben zhiwu",
          "price": 520,
          "producer": "waws producer",
          "tags": [
            "qingxin"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "3",
        "_score": 0.25811607,
        "_source": {
          "name": "zhonghua yagao",
          "desc": "caoben zhiwu",
          "price": 40,
          "producer": "zhonghua producer",
          "tags": [
            "qingxin"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "2",
        "_score": 0.16358379,
        "_source": {
          "name": "jiajieshi yagao",
          "desc": "youxiao fangzhu",
          "price": 25,
          "producer": "jiajieshi producer",
          "tags": [
            "fangzhu"
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "4",
        "_score": 0.16358379,
        "_source": {
          "name": "waws512 yagao",
          "desc": "bohe zhiwu",
          "price": 521,
          "producer": "waws producer",
          "tags": [
            "relax",
            "quwu"
          ]
        }
      }
    ]
  }
}
复制代码

phrase search(短语搜索)

跟全文检索相对应

  • 全文检索会将输入的搜索串拆解开来,去倒排索引里面去一一匹配,只要能匹配上任意一个拆解后的单词,就可以作为结果返回
  • phrase search,要求输入的搜索串,必须在指定的字段文本中,完全包含一模一样的,才可以算匹配,才能作为结果返回
GET /ecommerce/product/_search
{
    "query" : {
        "match_phrase" : {                          # 短语检索匹配
            "producer" : "yagao producer"
        }
    }
}

{
  "took": 6,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.51623213,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "1",
        "_score": 0.51623213,
        "_source": {
          "name": "jiaqiangban gaolujie yagao",
          "desc": "gaoxiao meibai",
          "price": 30,
          "producer": "yagao producer",
          "tags": [
            "meibai",
            "fangzhu"
          ]
        }
      }
    ]
  }
}
复制代码

6、highlight search(高亮搜索结果)

GET /ecommerce/product/_search
{
    "query" : {
        "match" : {
            "producer" : "waws"
        }
    },
    "highlight": {                  # hightlight 指定字段的文本高亮
        "fields" : {
            "producer" : {}
        }
    }
}

{
  "took": 2,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 0.62191015,
    "hits": [
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "4",
        "_score": 0.62191015,
        "_source": {
          "name": "waws512 yagao",
          "desc": "bohe zhiwu",
          "price": 521,
          "producer": "waws producer",
          "tags": [
            "relax",
            "quwu"
          ]
        },
        "highlight": {
          "producer": [
            "<em>waws</em> producer"     # 我们看到我们的match到的waws加上了一个标签
          ]
        }
      },
      {
        "_index": "ecommerce",
        "_type": "product",
        "_id": "5",
        "_score": 0.25811607,
        "_source": {
          "name": "waws520 yagao",
          "desc": "caoben zhiwu",
          "price": 520,
          "producer": "waws producer",
          "tags": [
            "qingxin"
          ]
        },
        "highlight": {
          "producer": [
            "<em>waws</em> producer"
          ]
        }
      }
    ]
  }
}
复制代码
文章分类
后端