为了演示不同类型的 ElasticSearch 的查询,我们将使用书文档信息的集合(有以下字段:title(标题), authors(作者), summary(摘要), publish_date(发布日期)和 num_reviews(浏览数))。

在这之前,首先我们应该先创建一个新的索引(index),并批量导入一些文档:

创建索引:

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

批量上传文档:

POST /bookdb_index/book/_bulk
{ "index": { "_id": }}
{ "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": , "publisher": "oreilly" }
{ "index": { "_id": }}
{ "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": , "publisher": "manning" }
{ "index": { "_id": }}
{ "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": , "publisher": "manning" }
{ "index": { "_id": }}
{ "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": , "publisher": "manning" }
栗子:

1. 基本的匹配(Query)查询

有两种方式来执行一个全文匹配查询:

  • 使用 Search Lite API,它从 url 中读取所有的查询参数
  • 使用完整 JSON 作为请求体,这样你可以使用完整的 Elasticsearch DSL

下面是一个基本的匹配查询,查询任一字段包含 Guide 的记录

GET /bookdb_index/book/_search?q=guide

[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
}
]

下面是完整 Body 版本的查询,生成相同的内容:

{
"query": {
"multi_match" : {
"query" : "guide",
"fields" : ["_all"]
}
}
}
multi_match 是 match 的作为在多个字段运行相同操作的一个速记法。fields 属性用来指定查询针对的字段,在这个例子中,我们想要对文档的所有字段进行匹配。两个 API 都允许你指定要查询的字段。例如,查询 title 字段中包含 in Action 的书: GET /bookdb_index/book/_search?q=title:in action [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
}
]

然而, 完整的 DSL 给予你灵活创建更复杂查询和指定返回结果的能力(后面,我们会一一阐述)。在下面例子中,我们指定 size限定返回的结果条数,from 指定起始位子,_source 指定要返回的字段,以及语法高亮

POST /bookdb_index/book/_search
{
"query": {
"match" : {
"title" : "in action"
}
},
"size": ,
"from": ,
"_source": [ "title", "summary", "publish_date" ],
"highlight": {
"fields" : {
"title" : {}
}
}
} [Results]
"hits": {
"total": ,
"max_score": 0.9105287,
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": "",
"_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:对于多个词查询,match 允许指定是否使用 and 操作符来取代默认的 or 操作符。你还可以指定 mininum_should_match选项来调整返回结果的相关程度。具体看后面的例子。

2. 多字段(Multi-filed)查询

正如我们已经看到来的,为了根据多个字段检索(e.g. 在 title 和 summary 字段都是相同的查询字符串的结果),你可以使用 multi_match 语句

POST /bookdb_index/book/_search
{
"query": {
"multi_match" : {
"query" : "elasticsearch guide",
"fields": ["title", "summary"]
}
}
} [Results]
"hits": {
"total": ,
"max_score": 0.9448582,
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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": ,
"publisher": "manning"
}
}
]
}

:第三条被匹配,因为 guide 在 summary 字段中被找到。

3. Boosting

由于我们是多个字段查询,我们可能需要提高某一个字段的分值。在下面的例子中,我们把 summary 字段的分数提高三倍,为了提升 summary 字段的重要度;因此,我们把文档 4 的相关度提高了。

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": "",
"_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": "",
"_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": "",
"_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"
}
}
]

:提升不是简简单单通过提升因子把计算分数加成。实际的 boost 值通过归一化和一些内部优化给出的。相关信息请见 Elasticsearch guide

4. Bool 查询

为了提供更相关或者特定的结果,AND/OR/NOT 操作符可以用来调整我们的查询。它是以 布尔查询 的方式来实现的。布尔查询 接受如下参数:

must 等同于 AND
must_not 等同于 NOT
should 等同于 OR

打比方,如果我想要查询这样类型的书:书名包含 ElasticSearch 或者(OR) Solr,并且(AND)它的作者是 Clinton Gormley 不是(NOTRadu Gheorge

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": "",
"_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": ,
"publisher": "oreilly"
}
}
]
:正如你所看到的,布尔查询 可以包装任何其他查询类型,包括其他布尔查询,以创建任意复杂或深度嵌套的查询。

5. 模糊(Fuzzy)查询

在进行匹配和多项匹配时,可以启用模糊匹配来捕捉拼写错误,模糊度是基于原始单词的编辑距离来指定的。

POST /bookdb_index/book/_search
{
"query": {
"multi_match" : {
"query" : "comprihensiv guide",
"fields": ["title", "summary"],
"fuzziness": "AUTO"
}
},
"_source": ["title", "summary", "publish_date"],
"size":
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_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"
}
}
]

:当术语长度大于 5 个字符时,AUTO 的模糊值等同于指定值 “2”。但是,80% 拼写错误的编辑距离为 1,所以,将模糊值设置为 1 可能会提高您的整体搜索性能。更多详细信息,请参阅Elasticsearch指南中的“排版和拼写错误”(Typos and Misspellings)

6. 通配符(Wildcard)查询

通配符查询 允许你指定匹配的模式,而不是整个术语。

? 匹配任何字符
* 匹配零个或多个字符。

例如,要查找名称以字母’t’开头的所有作者的记录:

POST /bookdb_index/book/_search
{
"query": {
"wildcard" : {
"authors" : "t*"
}
},
"_source": ["title", "authors"],
"highlight": {
"fields" : {
"authors" : {}
}
}
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"title": "Elasticsearch: The Definitive Guide",
"authors": [
"clinton gormley",
"zachary tong"
]
},
"highlight": {
"authors": [
"zachary <em>tong</em>"
]
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"authors": [
"grant ingersoll",
"thomas morton",
"drew farris"
]
},
"highlight": {
"authors": [
"<em>thomas</em> morton"
]
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"title": "Solr in Action",
"authors": [
"trey grainger",
"timothy potter"
]
},
"highlight": {
"authors": [
"<em>trey</em> grainger",
"<em>timothy</em> potter"
]
}
}
]

7. 正则(Regexp)查询

正则查询 让你可以使用比 通配符查询 更复杂的模式进行查询:

POST /bookdb_index/book/_search
{
"query": {
"regexp" : {
"authors" : "t[a-z]*y"
}
},
"_source": ["title", "authors"],
"highlight": {
"fields" : {
"authors" : {}
}
}
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"title": "Solr in Action",
"authors": [
"trey grainger",
"timothy potter"
]
},
"highlight": {
"authors": [
"<em>trey</em> grainger",
"<em>timothy</em> potter"
]
}
}
]

8. 短语匹配(Match Phrase)查询

短语匹配查询 要求在请求字符串中的所有查询项必须都在文档中存在,文中顺序也得和请求字符串一致,且彼此相连。默认情况下,查询项之间必须紧密相连,但可以设置 slop 值来指定查询项之间可以分隔多远的距离,结果仍将被当作一次成功的匹配。

POST /bookdb_index/book/_search
{
"query": {
"multi_match" : {
"query": "search engine",
"fields": ["title", "summary"],
"type": "phrase",
"slop":
}
},
"_source": [ "title", "summary", "publish_date" ]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.22327082,
"_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": "",
"_score": 0.16113183,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]

:在上述例子中,对于非整句类型的查询,_id 为 1 的文档一般会比 _id 为 4 的文档得分高,结果位置也更靠前,因为它的字段长度较短,但是对于 短语匹配类型 查询,由于查询项之间的接近程度是一个计算因素,因此 _id 为 4 的文档得分更高。

9. 短语前缀(Match Phrase Prefix)查询

短语前缀式查询 能够进行 即时搜索(search-as-you-type) 类型的匹配,或者说提供一个查询时的初级自动补全功能,无需以任何方式准备你的数据。和 match_phrase 查询类似,它接收slop 参数(用来调整单词顺序和不太严格的相对位置)和 max_expansions参数(用来限制查询项的数量,降低对资源需求的强度)。

POST /bookdb_index/book/_search
{
"query": {
"match_phrase_prefix" : {
"summary": {
"query": "search en",
"slop": ,
"max_expansions":
}
}
},
"_source": [ "title", "summary", "publish_date" ]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.5161346,
"_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": "",
"_score": 0.37248808,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]

:采用 查询时即时搜索 具有较大的性能成本。更好的解决方案是采用 索引时即时搜索。更多信息,请查看 自动补齐接口(Completion Suggester API) 或 边缘分词器(Edge-Ngram filters)的用法

10. 查询字符串(Query String)

查询字符串 类型(query_string)的查询提供了一个方法,用简洁的简写语法来执行 多匹配查询、 布尔查询 、 提权查询、 模糊查询、 通配符查询、 正则查询 和范围查询。下面的例子中,我们在那些作者是 “grant ingersoll” 或 “tom morton” 的某本书当中,使用查询项 “search algorithm” 进行一次模糊查询,搜索全部字段,但给 summary 的权重提升 2 倍。

POST /bookdb_index/book/_search
{
"query": {
"query_string" : {
"query": "(saerch~1 algorithm~1) AND (grant ingersoll) OR (tom morton)",
"fields": ["_all", "summary^2"]
}
},
"_source": [ "title", "summary", "authors" ],
"highlight": {
"fields" : {
"summary" : {}
}
}
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.14558059,
"_source": {
"summary": "organize text using approaches such as full-text search, proper name recognition, clustering, tagging, information extraction, and summarization",
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"authors": [
"grant ingersoll",
"thomas morton",
"drew farris"
]
},
"highlight": {
"summary": [
"organize text using approaches such as full-text <em>search</em>, proper name recognition, clustering, tagging, information extraction, and summarization"
]
}
}
]

11. 简单查询字符串(Simple Query String)

简单请求字符串 类型(simple_query_string)的查询是请求字符串类型query_string)查询的一个版本,它更适合那种仅暴露给用户一个简单搜索框的场景;因为它用 +/\|/- 分别替换了 AND/OR/NOT,并且自动丢弃了请求中无效的部分,不会在用户出错时,抛出异常。

POST /bookdb_index/book/_search
{
"query": {
"simple_query_string" : {
"query": "(saerch~1 algorithm~1) + (grant ingersoll) | (tom morton)",
"fields": ["_all", "summary^2"]
}
},
"_source": [ "title", "summary", "authors" ],
"highlight": {
"fields" : {
"summary" : {}
}
}
}

12. 词条(Term)/多词条(Terms)查询

以上例子均为 full-text(全文检索) 的示例。有时我们对结构化查询更感兴趣,希望得到更准确的匹配并返回结果,词条查询 和 多词条查询 可帮我们实现。在下面的例子中,我们要在索引中找到所有由 Manning 出版的图书。

POST /bookdb_index/book/_search
{
"query": {
"term" : {
"publisher": "manning"
}
},
"_source" : ["title","publish_date","publisher"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 1.2231436,
"_source": {
"publisher": "manning",
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 1.2231436,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 1.2231436,
"_source": {
"publisher": "manning",
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
}
]

可使用词条关键字来指定多个词条,将搜索项用数组传入。

{
"query": {
"terms" : {
"publisher": ["oreilly", "packt"]
}
}
}

13. 词条(Term)查询 - 排序(Sorted)

词条查询 的结果(和其他查询结果一样)可以被轻易排序,多级排序也被允许:

POST /bookdb_index/book/_search
{
"query": {
"term" : {
"publisher": "manning"
}
},
"_source" : ["title","publish_date","publisher"],
"sort": [
{ "publish_date": {"order":"desc"}},
{ "title": { "order": "desc" }}
]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
},
"sort": [
,
"in"
]
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Solr in Action",
"publish_date": "2014-04-05"
},
"sort": [
,
"solr"
]
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
},
"sort": [
,
"to"
]
}
]
14. 范围查询

另一个结构化查询的例子是 范围查询。在这个例子中,我们要查找 2015 年出版的书。

POST /bookdb_index/book/_search
{
"query": {
"range" : {
"publish_date": {
"gte": "2015-01-01",
"lte": "2015-12-31"
}
}
},
"_source" : ["title","publish_date","publisher"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"publisher": "oreilly",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": ,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
}
]

范围查询 用于日期、数字和字符串类型的字段。

15. 过滤(Filtered)查询

过滤查询允许你可以过滤查询结果。对于我们的例子中,要在标题或摘要中检索一些书,查询项为 Elasticsearch,但我们又想筛出那些仅有 20 个以上评论的。

POST /bookdb_index/book/_search
{
"query": {
"filtered": {
"query" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"range" : {
"num_reviews": {
"gte":
}
}
}
}
},
"_source" : ["title","summary","publisher", "num_reviews"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.5955761,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"publisher": "oreilly",
"num_reviews": ,
"title": "Elasticsearch: The Definitive Guide"
}
}
]

过滤查询 并不强制它作用于其上的查询必须存在。如果未指定查询,match_all 基本上会返回索引内的全部文档。实际上,过滤只在第一次运行,以减少所需的查询面积,并且,在第一次使用后过滤会被缓存,大大提高了性能。

更新过滤查询 将在 ElasticSearch 5 中移除,使用 布尔查询 替代。 下面有个例子使用 布尔查询 重写上面的例子:

POST /bookdb_index/book/_search
{
"query": {
"bool": {
"must" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"range" : {
"num_reviews": {
"gte":
}
}
}
}
},
"_source" : ["title","summary","publisher", "num_reviews"]
}

在后续的例子中,我们将会把它使用在 多重过滤 中。

16. 多重过滤(Multiple Filters)

多重过滤 可以结合 布尔查询 使用,下一个例子中,过滤查询决定只返回那些包含至少20条评论,且必须在 2015 年前出版,且由 O’Reilly 出版的结果。

POST /bookdb_index/book/_search
{
"query": {
"filtered": {
"query" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"bool": {
"must": {
"range" : { "num_reviews": { "gte": } }
},
"must_not": {
"range" : { "publish_date": { "lte": "2014-12-31" } }
},
"should": {
"term": { "publisher": "oreilly" }
}
}
}
}
},
"_source" : ["title","summary","publisher", "num_reviews", "publish_date"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.5955761,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"publisher": "oreilly",
"num_reviews": ,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]

17. 作用分值: 域值(Field Value)因子

也许在某种情况下,你想把文档中的某个特定域作为计算相关性分值的一个因素,比较典型的场景是你想根据普及程度来提高一个文档的相关性。在我们的示例中,我们想把最受欢迎的书(基于评论数判断)的权重进行提高,可使用 field_value_factor 用以影响分值。

POST /bookdb_index/book/_search
{
"query": {
"function_score": {
"query": {
"multi_match" : {
"query" : "search engine",
"fields": ["title", "summary"]
}
},
"field_value_factor": {
"field" : "num_reviews",
"modifier": "log1p",
"factor" :
}
}
},
"_source": ["title", "summary", "publish_date", "num_reviews"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.44831306,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": ,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.3718407,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": ,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.046479136,
"_source": {
"summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
"num_reviews": ,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.041432835,
"_source": {
"summary": "organize text using approaches such as full-text search, proper name recognition, clustering, tagging, information extraction, and summarization",
"num_reviews": ,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
}
]

注1: 我们可能刚运行了一个常规的 multi_match (多匹配)查询,并对 num_reviews 域进行了排序,这让我们失去了评估相关性分值的好处。

注2: 有大量的附加参数可用来调整提升原始相关性分值效果的程度,比如 modifierfactorboost_mode 等等,至于细节可在 Elasticsearch 指南中探索。

18. 作用分值: 衰变(Decay)函数

假设不想使用域值做递增提升,而你有一个理想目标值,并希望用这个加权因子来对这个离你较远的目标值进行衰减。有个典型的用途是基于经纬度、价格或日期等数值域的提升。在如下的例子中,我们查找在2014年6月左右出版的,查询项是 search engines 的书。

POST /bookdb_index/book/_search
{
"query": {
"function_score": {
"query": {
"multi_match" : {
"query" : "search engine",
"fields": ["title", "summary"]
}
},
"functions": [
{
"exp": {
"publish_date" : {
"origin": "2014-06-15",
"offset": "7d",
"scale" : "30d"
}
}
}
],
"boost_mode" : "replace"
}
},
"_source": ["title", "summary", "publish_date", "num_reviews"]
} [Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.27420625,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": ,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.005920768,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": ,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.000011564,
"_source": {
"summary": "organize text using approaches such as full-text search, proper name recognition, clustering, tagging, information extraction, and summarization",
"num_reviews": ,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.0000059171475,
"_source": {
"summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
"num_reviews": ,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
}
]

19. 函数分值: 脚本评分

当内置的评分函数无法满足你的需求时,还可以用 Groovy 脚本。在我们的例子中,想要指定一个脚本,能在决定把 num_reviews 的因子计算多少之前,先将 publish_date 考虑在内。因为很新的书也许不会有评论,分值不应该被惩罚。

评分脚本如下:

publish_date = doc['publish_date'].value
num_reviews = doc['num_reviews'].value if (publish_date > Date.parse('yyyy-MM-dd', threshold).getTime()) {
my_score = Math.log(2.5 + num_reviews)
} else {
my_score = Math.log( + num_reviews)
}
return my_score
在 script_score 参数内动态调用评分脚本: POST /bookdb_index/book/_search
{
"query": {
"function_score": {
"query": {
"multi_match" : {
"query" : "search engine",
"fields": ["title", "summary"]
}
},
"functions": [
{
"script_score": {
"params" : {
"threshold": "2015-07-30"
},
"script": "publish_date = doc['publish_date'].value; num_reviews = doc['num_reviews'].value; if (publish_date > Date.parse('yyyy-MM-dd', threshold).getTime()) { return log(2.5 + num_reviews) }; return log(1 + num_reviews);"
}
}
]
}
},
"_source": ["title", "summary", "publish_date", "num_reviews"]
} [Results]
"hits": {
"total": ,
"max_score": 0.8463001,
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.8463001,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": ,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.7067348,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": ,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.08952084,
"_source": {
"summary": "build scalable search applications using Elasticsearch without having to do complex low-level programming or understand advanced data science algorithms",
"num_reviews": ,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "",
"_score": 0.07602123,
"_source": {
"summary": "organize text using approaches such as full-text search, proper name recognition, clustering, tagging, information extraction, and summarization",
"num_reviews": ,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
}
]
}

注1: 要在 Elasticsearch 实例中使用动态脚本,必须在 config/elasticsearch.yaml 文件中启用它;也可以使用存储在 Elasticsearch 服务器上的脚本。建议看看 Elasticsearch 指南文档获取更多信息。

注2: 因 JSON 不能包含嵌入式换行符,请使用分号来分割语句。

转:https://n3xtchen.github.io/n3xtchen/elasticsearch/2017/07/05/elasticsearch-23-useful-query-example

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