ElasticSearch多种搜索方式

上一章节主要介绍了ES的一些重要概念及简单的CRUD，本章内容将重点介绍ES的多种查询方式。ES在使用过程中，查询是最重要的应用场景。

一、Query String Search(‘Query String’方式的搜索)

1.搜索全部商品

GET /shop_index/productInfo/_search

返回结果：

{
  "took": 8,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 3,
    "max_score": 1,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "2",
        "_score": 1,
        "_source": {
          "test": "test"
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": 1,
        "_source": {
          "name": "HuaWei P20",
          "desc": "Expen but easy to use",
          "price": 5300,
          "producer": "HuaWei Producer",
          "tags": [
            "Expen",
            "Fast"
          ]
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "1",
        "_score": 1,
        "_source": {
          "name": "HuaWei Mate8",
          "desc": "Cheap and easy to use",
          "price": 2500,
          "producer": "HuaWei Producer",
          "tags": [
            "Cheap",
            "Fast"
          ]
        }
      }
    ]
  }
}

字段解释：

took:耗费了几毫秒
timed_out:是否超时，这里是没有
_shards:数据被拆到了5个分片上，搜索时使用了5个分片，5个分片都成功地返回了数据，失败了0个，跳过了0个
hits.total:查询结果的数量，3个document
max_score:就是document对于一个search的相关度的匹配分数，越相关，就越匹配，分数也越高
hits.hits:包含了匹配搜索的document的详细数据

2.搜索商品名称中包含HuaWei的商品，而且按照售价降序排序：
下面这种方法也是"Query String Search"的由来，因为search参数都是以http请求的query string来附带的.

GET /shop_index/productInfo/_search?q=name:HuaWei&sort=price:desc

返回结果：

{
  "took": 23,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": null,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": null,
        "_source": {
          "name": "HuaWei P20",
          "desc": "Expen but easy to use",
          "price": 5300,
          "producer": "HuaWei Producer",
          "tags": [
            "Expen",
            "Fast"
          ]
        },
        "sort": [
          5300
        ]
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "1",
        "_score": null,
        "_source": {
          "name": "HuaWei Mate8",
          "desc": "Cheap and easy to use",
          "price": 2500,
          "producer": "HuaWei Producer",
          "tags": [
            "Cheap",
            "Fast"
          ]
        },
        "sort": [
          2500
        ]
      }
    ]
  }
}

二、Query DSL(DSL: Domain Specified Language，特定领域的语言)

这种方法是通过一个json格式的http request body请求体作为条件，可以完成多种复杂的查询需求，比query string的功能更加强大
1.搜索所有商品

GET /shop_index/productInfo/_search
{
  "query": {
    "match_all": {}
  }
}

返回结果省略...

2.查询名称中包含HuaWei的商品，并且按照价格降序排列

GET /shop_index/productInfo/_search
{
  "query": {
    "match": {
      "name": "HuaWei"
    }
  },
  "sort": [
    {
      "price": {
        "order": "desc"
      }
    }
  ]
}

返回结果省略...

3.分页查询第二页，每页1条记录

GET /shop_index/productInfo/_search
{
  "query": {
    "match_all": {}
  },
  "from": 1,
  "size": 1
}

返回结果：

{
  "took": 6,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 3,
    "max_score": 1,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": 1,
        "_source": {
          "name": "HuaWei P20",
          "desc": "Expen but easy to use",
          "price": 5300,
          "producer": "HuaWei Producer",
          "tags": [
            "Expen",
            "Fast"
          ]
        }
      }
    ]
  }
}

注意：
(1)在实际项目中，如果有条件查询之后再需要分页，不需要单独查询总条数，ES会返回满足条件的总条数，可以直接使用；
(2)ES的分页默认from是从0开始的；

4.只查询特定字段，比如：name，desc和price字段，其他字段不需要返回

GET /shop_index/productInfo/_search
{
  "query": {
    "match": {
      "name": "HuaWei"
    }
  },
  "_source": ["name","desc","price"]
}

返回结果：

{
  "took": 27,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 0.2876821,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": 0.2876821,
        "_source": {
          "price": 5300,
          "name": "HuaWei P20",
          "desc": "Expen but easy to use"
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "1",
        "_score": 0.2876821,
        "_source": {
          "price": 2500,
          "name": "HuaWei Mate8",
          "desc": "Cheap and easy to use"
        }
      }
    ]
  }
}

三.Query Filter(对查询结果进行过滤)

比如：查询名称中包含HuaWei，并且价格大于4000的商品记录:

GET /shop_index/productInfo/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "name": "HuaWei"
          }
        }
      ], 
      "filter": {
        "range": {
          "price": {
            "gt": 4000
          }
        }
      }
    }
  }
}

返回结果：

{
  "took": 195,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.2876821,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": 0.2876821,
        "_source": {
          "name": "HuaWei P20",
          "desc": "Expen but easy to use",
          "price": 5300,
          "producer": "HuaWei Producer",
          "tags": [
            "Expen",
            "Fast"
          ]
        }
      }
    ]
  }
}

四、全文索引(Full-Text Search)

搜索生产厂商字段中包含"HuaWei MateProducer"的商品记录：

GET /shop_index/productInfo/_search
{
  "query": {
    "match": {
      "producer": "HuaWei MateProducer"
    }
  }
}

返回结果：

{
  "took": 8,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 4,
    "max_score": 0.5753642,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "SiUBRWkB8mgaHjxkJHyS",
        "_score": 0.5753642,
        "_source": {
          "name": "HuaWei Mate10",
          "desc": "Cheap and Beauti",
          "price": 2300,
          "producer": "HuaWei MateProducer",
          "tags": [
            "Cheap",
            "Beauti"
          ]
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "1",
        "_score": 0.2876821,
        "_source": {
          "name": "HuaWei Mate8",
          "desc": "Cheap and easy to use",
          "price": 2500,
          "producer": "HuaWei Producer",
          "tags": [
            "Cheap",
            "Fast"
          ]
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "zyWpRGkB8mgaHjxk0Hfo",
        "_score": 0.18232156,
        "_source": {
          "name": "HuaWei P20",
          "desc": "Expen but easy to use",
          "price": 5300,
          "producer": "HuaWei Producer",
          "tags": [
            "Expen",
            "Fast"
          ]
        }
      },
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "CSX8RGkB8mgaHjxkV3w1",
        "_score": 0.18232156,
        "_source": {
          "name": "HuaWei nova 4e",
          "desc": "cheap and look nice",
          "price": 1999,
          "producer": "HuaWei Producer",
          "tags": [
            "Cheap",
            "Nice"
          ]
        }
      }
    ]
  }
}

从以上结果中可以看到：
id为"SiUBRWkB8mgaHjxkJHyS"的记录score分数最高，表示匹配度最高;
原因：
producer分完词之后包括的词语有：
(1).HuaWei:
匹配到改词的记录ID：'SiUBRWkB8mgaHjxkJHyS','1','CSX8RGkB8mgaHjxkV3w1','zyWpRGkB8mgaHjxk0Hfo'
(2).MateProducer:
匹配到该词的记录ID：'SiUBRWkB8mgaHjxkJHyS'
由于"HuaWei MateProducer"两次匹配到ID为'SiUBRWkB8mgaHjxkJHyS'的记录，所以该记录的score分数最高。

五、Phrase Search(短语搜索)

短语索引和全文索引的区别：
(1)全文匹配：将要搜索的内容分词，然后挨个单词去倒排索引中匹配，只要匹配到任意一个单词，就算是匹配到记录;
(2)短语索引：输入的搜索串，必须在指定的字段内容中，完全包含一模一样的，才可以算匹配，才能作为结果返回;
例如：搜索name中包含"HuaWei MateProducer"短语的商品信息:

GET /shop_index/productInfo/_search
{
  "query": {
    "match_phrase": {
      "producer": "HuaWei MateProducer"
    }
  }
}

返回结果：

{
  "took": 158,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.5753642,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "SiUBRWkB8mgaHjxkJHyS",
        "_score": 0.5753642,
        "_source": {
          "name": "HuaWei Mate10",
          "desc": "Cheap and Beauti",
          "price": 2300,
          "producer": "HuaWei MateProducer",
          "tags": [
            "Cheap",
            "Beauti"
          ]
        }
      }
    ]
  }
}

可以看到只有包含"HuaWei MateProducer"的记录才被返回。

六、Highlight Search(搜索高亮显示)

高亮搜索指的是搜索的结果中，将某些特别需要强调的词使用特定的样式展示出来。
例如：搜索商品名称中包含"Xiao'Mi"的商品，并将搜索的关键词高亮显示：

GET /shop_index/productInfo/_search
{
  "query": {
    "match": {
      "name": "Xiao'Mi"
    }
  },
  "highlight": {
    "fields": {
      "name": {}
    }
  }
}

返回结果：

{
  "took": 348,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.2876821,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "HiX9RGkB8mgaHjxk4nxC",
        "_score": 0.2876821,
        "_source": {
          "name": "Xiao'Mi 9",
          "desc": "Expen but nice and Beauti",
          "price": 3500,
          "producer": "XiaoMi Producer",
          "tags": [
            "Expen",
            "Beauti"
          ]
        },
        "highlight": {
          "name": [
            "<em>Xiao'Mi</em> 9"
          ]
        }
      }
    ]
  }
}

可以看到，"Xiao'Mi"使用了标签返回了，可以在HTML中直接以斜体展示。
如果想使用自定义高亮样式，可以使用pre_tags和post_tags进行自定义，比如：想使用红色展示，如下所示：

GET /shop_index/productInfo/_search
{
  "query": {
    "match": {
      "name": "Xiao'Mi"
    }
  },
  "highlight": {
    "fields": {
      "name": {}
    },
    "pre_tags": [
      "<em style='color:red;'>"
    ],
    "post_tags": [
      "</em>"
    ]
  }
}

返回结果：

{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 0.2876821,
    "hits": [
      {
        "_index": "shop_index",
        "_type": "productInfo",
        "_id": "HiX9RGkB8mgaHjxk4nxC",
        "_score": 0.2876821,
        "_source": {
          "name": "Xiao'Mi 9",
          "desc": "Expen but nice and Beauti",
          "price": 3500,
          "producer": "XiaoMi Producer",
          "tags": [
            "Expen",
            "Beauti"
          ]
        },
        "highlight": {
          "name": [
            "<em style='color:red;'>Xiao'Mi</em> 9"
          ]
        }
      }
    ]
  }
}

返回结果中的搜索关键字使用表示红色的css样式展示出来。

ES的多种搜索方式到此介绍完毕，每种搜索方式中还包含其他的API，文中没有全部介绍，如果有需要可以自行翻阅官方文档。欢迎评论转发！