常用的Elasticseaerch检索技巧汇总

　　 　本篇博客是对前期工作中遇到ES坑的一些小结，顺手记录下，方便日后查阅。

0、前言

为了讲解不同类型ES检索，我们将要对包含以下类型的文档集合进行检索：

1. title 标题； 
 2. authors 作者； 
 3. summary 摘要； 
 4. release data 发布日期； 
 5. number of reviews 评论数。

首先，让我们借助 bulk API批量创建新的索引并提交数据。

PUT /bookdb_index
    { "settings": { "number_of_shards": 1 }}

POST /bookdb_index/book/_bulk
    { "index": { "_id": 1 }}
    { "title": "Elasticsearch: The Definitive Guide", "authors": ["clinton gormley", "zachary tong"], "summary" : "A distibuted real-time search and analytics engine", "publish_date" : "2015-02-07", "num_reviews": 20, "publisher": "oreilly" }
    { "index": { "_id": 2 }}
    { "title": "Taming Text: How to Find, Organize, and Manipulate It", "authors": ["grant ingersoll", "thomas morton", "drew farris"], "summary" : "organize text using approaches such as full-text search, proper name recognition, clustering, tagging, information extraction, and summarization", "publish_date" : "2013-01-24", "num_reviews": 12, "publisher": "manning" }
    { "index": { "_id": 3 }}
    { "title": "Elasticsearch in Action", "authors": ["radu gheorge", "matthew lee hinman", "roy russo"], "summary" : "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms", "publish_date" : "2015-12-03", "num_reviews": 18, "publisher": "manning" }
    { "index": { "_id": 4 }}

1、基本匹配检索( Basic Match Query)

1.1 全文检索

有两种方式可以执行全文检索： 
1）使用包含参数的检索API，参数作为URL的一部分。

举例：以下对”guide”执行全文检索。

GET /bookdb_index/book/_search?q=guide

[Results]
"hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "1",
        "_score": 0.28168046,
        "_source": {
          "title": "Elasticsearch: The Definitive Guide",
          "authors": [
            "clinton gormley",
            "zachary tong"
          ],
          "summary": "A distibuted real-time search and analytics engine",
          "publish_date": "2015-02-07",
          "num_reviews": 20,
          "publisher": "manning"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.24144039,
        "_source": {
          "title": "Solr in Action",
          "authors": [
            "trey grainger",
            "timothy potter"
          ],
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "publish_date": "2014-04-05",
          "num_reviews": 23,
          "publisher": "manning"
        }
      }
    ]

2）使用完整的ES DSL，其中Json body作为请求体。 
其执行结果如方式1）结果一致。

{
    "query": {
        "multi_match" : {
            "query" : "guide",
            "fields" : ["_all"]
        }
    }
}

解读：使用multi_match关键字代替match关键字，作为对多个字段运行相同查询的方便的简写方式。 fields属性指定要查询的字段，在这种情况下，我们要对文档中的所有字段进行查询。

1.2 指定特定字段检索

这两个API也允许您指定要搜索的字段。 例如，要在标题字段中搜索带有“in action”字样的图书， 
1）URL检索方式 
如下所示：

GET /bookdb_index/book/_search?q=title:in action


[Results]
"hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.6259885,
        "_source": {
          "title": "Solr in Action",
          "authors": [
            "trey grainger",
            "timothy potter"
          ],
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "publish_date": "2014-04-05",
          "num_reviews": 23,
          "publisher": "manning"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "3",
        "_score": 0.5975345,
        "_source": {
          "title": "Elasticsearch in Action",
          "authors": [
            "radu gheorge",
            "matthew lee hinman",
            "roy russo"
          ],
          "summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
          "publish_date": "2015-12-03",
          "num_reviews": 18,
          "publisher": "manning"
        }
      }
    ]

2）DSL检索方式 
然而，full body的DSL为您提供了创建更复杂查询的更多灵活性（我们将在后面看到）以及指定您希望的返回结果。 在下面的示例中，我们指定要返回的结果数、偏移量（对分页有用）、我们要返回的文档字段以及属性的高亮显示。 
结果数的表示方式：size; 
偏移值的表示方式：from; 
指定返回字段 的表示方式 ：_source; 
高亮显示 的表示方式 ：highliaght。

POST /bookdb_index/book/_search
{
    "query": {
        "match" : {
            "title" : "in action"
        }
    },
    "size": 2,
    "from": 0,
    "_source": [ "title", "summary", "publish_date" ],
    "highlight": {
        "fields" : {
            "title" : {}
        }
    }
}


[Results]
"hits": {
    "total": 2,
    "max_score": 0.9105287,
    "hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "3",
        "_score": 0.9105287,
        "_source": {
          "summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
          "title": "Elasticsearch in Action",
          "publish_date": "2015-12-03"
        },
        "highlight": {
          "title": [
            "Elasticsearch <em>in</em> <em>Action</em>"
          ]
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.9105287,
        "_source": {
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "title": "Solr in Action",
          "publish_date": "2014-04-05"
        },
        "highlight": {
          "title": [
            "Solr <em>in</em> <em>Action</em>"
          ]
        }
      }
    ]
  }

注意:对于 multi-word 检索，匹配查询允许您指定是否使用‘and’运算符， 

而不是使用默认’or’运算符。 
您还可以指定minimum_should_match选项来调整返回结果的相关性。 
详细信息可以在Elasticsearch指南中查询Elasticsearch guide. 获取。

2、多字段检索 (Multi-field Search)

如我们已经看到的，要在搜索中查询多个文档字段（例如在标题和摘要中搜索相同的查询字符串），请使用multi_match查询。

POST /bookdb_index/book/_search
{
    "query": {
        "multi_match" : {
            "query" : "elasticsearch guide",
            "fields": ["title", "summary"]
        }
    }
}


[Results]
"hits": {
    "total": 3,
    "max_score": 0.9448582,
    "hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "1",
        "_score": 0.9448582,
        "_source": {
          "title": "Elasticsearch: The Definitive Guide",
          "authors": [
            "clinton gormley",
            "zachary tong"
          ],
          "summary": "A distibuted real-time search and analytics engine",
          "publish_date": "2015-02-07",
          "num_reviews": 20,
          "publisher": "manning"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "3",
        "_score": 0.17312013,
        "_source": {
          "title": "Elasticsearch in Action",
          "authors": [
            "radu gheorge",
            "matthew lee hinman",
            "roy russo"
          ],
          "summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
          "publish_date": "2015-12-03",
          "num_reviews": 18,
          "publisher": "manning"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.14965448,
        "_source": {
          "title": "Solr in Action",
          "authors": [
            "trey grainger",
            "timothy potter"
          ],
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "publish_date": "2014-04-05",
          "num_reviews": 23,
          "publisher": "manning"
        }
      }
    ]
  }

注意：以上结果3匹配的原因是guide在summary存在。

3、 Boosting提升某字段得分的检索( Boosting)

由于我们正在多个字段进行搜索，我们可能希望提高某一字段的得分。 在下面的例子中，我们将“摘要”字段的得分提高了3倍，以增加“摘要”字段的重要性，从而提高文档 4 的相关性。

POST /bookdb_index/book/_search
{
    "query": {
        "multi_match" : {
            "query" : "elasticsearch guide",
            "fields": ["title", "summary^3"]
        }
    },
    "_source": ["title", "summary", "publish_date"]
}


[Results]
"hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "1",
        "_score": 0.31495273,
        "_source": {
          "summary": "A distibuted real-time search and analytics engine",
          "title": "Elasticsearch: The Definitive Guide",
          "publish_date": "2015-02-07"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.14965448,
        "_source": {
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "title": "Solr in Action",
          "publish_date": "2014-04-05"
        }
      },
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "3",
        "_score": 0.13094766,
        "_source": {
          "summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
          "title": "Elasticsearch in Action",
          "publish_date": "2015-12-03"
        }
      }
    ]

注意：Boosting不仅意味着计算得分乘法以增加因子。 实际的提升得分值是通过归一化和一些内部优化。参考 Elasticsearch guide.查看更多。

4、Bool检索( Bool Query)

可以使用AND / OR / NOT运算符来微调我们的搜索查询，以提供更相关或指定的搜索结果。

在搜索API中是通过bool查询来实现的。 
bool查询接受”must”参数（等效于AND），一个must_not参数（相当于NOT）或者一个should参数（等同于OR）。

例如，如果我想在标题中搜索一本名为“Elasticsearch”或“Solr”的书，AND由“clinton gormley”创作，但NOT由“radu gheorge”创作：

POST /bookdb_index/book/_search
{
    "query": {
        "bool": {
            "must": {
                "bool" : { "should": [
                      { "match": { "title": "Elasticsearch" }},
                      { "match": { "title": "Solr" }} ] }
            },
            "must": { "match": { "authors": "clinton gormely" }},
            "must_not": { "match": {"authors": "radu gheorge" }}
        }
    }
}


[Results]
"hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "1",
        "_score": 0.3672021,
        "_source": {
          "title": "Elasticsearch: The Definitive Guide",
          "authors": [
            "clinton gormley",
            "zachary tong"
          ],
          "summary": "A distibuted real-time search and analytics engine",
          "publish_date": "2015-02-07",
          "num_reviews": 20,
          "publisher": "oreilly"
        }
      }
    ]

注意：您可以看到，bool查询可以包含任何其他查询类型，包括其他布尔查询，以创建任意复杂或深度嵌套的查询。

5、 Fuzzy 模糊检索( Fuzzy Queries)

在 Match检索 和多匹配检索中可以启用模糊匹配来捕捉拼写错误。 基于与原始词的Levenshtein距离来指定模糊度。

POST /bookdb_index/book/_search
{
    "query": {
        "multi_match" : {
            "query" : "comprihensiv guide",
            "fields": ["title", "summary"],
            "fuzziness": "AUTO"
        }
    },
    "_source": ["title", "summary", "publish_date"],
    "size": 1
}


[Results]
"hits": [
      {
        "_index": "bookdb_index",
        "_type": "book",
        "_id": "4",
        "_score": 0.5961596,
        "_source": {
          "summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
          "title": "Solr in Action",
          "publish_date": "2014-04-05"
        }
      }
    ]

“AUTO”的模糊值相当于当字段长度大于5时指定值2。但是，设置80％的拼写错误的编辑距离为1，将模糊度设置为1可能会提高整体搜索性能。 有关更多信息， Typos and Misspellingsch 。

https://blog.csdn.net/laoyang360/article/details/76769208 从6开始