23 款實用的 Elasticsearch 查詢示例
ElasticSearch是一個基於Lucene的搜索服務器，它是用Java開發的，並做爲Apache許可條款下的開放源碼發佈，是當前流行的企業級搜索引擎。本文介紹了幾種經常使用的Elasticsearch查詢方式，並分別進行了舉例，但願它們對你有幫助。（注：文章翻譯自Tim Ojo的23 Useful Elasticsearch Example Queries。如有翻譯不到位的地方，歡迎你們進行指正。喜歡的也不要忘了打賞、點贊、收藏哦：)）html
爲了介紹Elasticsearch中的不一樣查詢類型，咱們將對帶有下列字段的文檔進行搜索：title（標題），authors（做者），summary（摘要），release date（發佈時間）以及number of reviews（評論數量）。
首先，讓咱們建立一個新的索引，並經過bulk API查詢文檔：算法
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 }}
{ "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" }
舉例
基本匹配查詢
有兩種方式執行基本全文（匹配）查詢：使用Search Lite API，它將搜索參數做爲URL的一部分傳遞；使用完整的JSON請求消息體，它容許你使用完整的Elasticsearch DSL。數組
如下是基本的匹配查詢，在全部字段中查詢字符串「guide」：緩存
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"
}
}
]
這個查詢的完整消息體以下，它產生的結果與上述查詢相同：服務器
{
"query": {
"multi_match" : {
"query" : "guide",
"fields" : ["_all"]
}
}
}
做爲對多個字段運行相同查詢的簡便方法，multi_match關鍵字能夠用在match關鍵字的位置。fields屬性指定要查詢的字段，在這種狀況下，咱們要對文檔中的全部字段進行查詢。app
兩種API都容許你指定你想查詢的字段。好比，指定搜索標題字段中含「in Action」的圖書：elasticsearch
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"
}
}
]
然而，完整的DSL能提供更大的靈活性，讓你能夠建立更復雜的查詢（咱們在下文會提到）以及指定查詢結果的返回方式。在下列示例中，咱們指定了要返回的結果數量、偏移位置（對分頁有用）、要返回的文檔字段和高亮顯示的項。ide
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：對於多詞（multi-word）查詢，相應的匹配（match）查詢容許你指定是否使用and運算符，而不是默認使用or運算符。你也能夠指定minimum_should_match選項來調整返回結果的相關性。詳細信息能夠在Elasticsearch指南中找到。函數
多字段查詢
爲了在一次查詢中查找多個字段（如，在title和summary中查找相同的字符串），你使用了multi_match查詢：性能
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：上面的查詢匹配了3個結果，由於單詞「guide」在summary（摘要）中有出現。
Boosting 算法
有時候，咱們在多個字段中進行搜索，可能會但願提升某個字段中的權重。如，在下列設計示例中，咱們將summary字段的權重提升三倍，以提升這個字段的重要性，從而加強文檔 _id 4的相關性。
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：Boosting並不意味着計算的權重會被boost因子翻倍。實際的boost值會進行一些規範化和內部優化。想了解更多boost工做原理的信息，可參考Elasticsearch指南。
Bool 查詢
爲得到更具相關性和更具體的查詢結果，AND / OR / NOT運算符可在咱們的搜索查詢進行微調。這在搜索API中做爲bool查詢實現。bool查詢接受must參數（等效於AND），must_not參數（等效於NOT），should參數（等效於OR）。好比，我想查詢標題中帶有「Elasticsearch」 或（OR） 「Solr」的書，而且（AND）是由「clinton gormley」創做，而不是（NOT） 「radu 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": "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：如你所見，bool查詢囊括全部其餘的搜索類型，包括其餘類型的bool查詢，以構建複雜和深層嵌套的查詢體系。
模糊查詢
模糊匹配能夠在匹配和多重匹配查詢上啓用以捕獲拼寫錯誤。模糊程度由原始詞之間的Levenshtein距離決定。
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"
}
}
]
注：當術語長度大於5個字符時，"AUTO"的模糊值等同於指定值「2」。可是，80％的人類拼寫錯誤的編輯距離爲1，因此，將模糊值設置爲「1」可能會提升您的總體搜索性能。更多詳細信息，請參閱Elasticsearch指南中的「排版和拼寫錯誤」（Typos and Misspellings）章節。
通配符查詢
通配符查詢容許你指定匹配的模式，而不是整個術語。？ 匹配任何字符，*匹配零個或多個字符。例如，要查找名稱以字母't'開頭的全部做者的記錄：
POST /bookdb_index/book/_search
{
"query": {
"wildcard" : {
"authors" : "t*"
}
},
"_source": ["title", "authors"],
"highlight": {
"fields" : {
"authors" : {}
}
}
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "1",
"_score": 1,
"_source": {
"title": "Elasticsearch: The Definitive Guide",
"authors": [
"clinton gormley",
"zachary tong"
]
},
"highlight": {
"authors": [
"zachary <em>tong</em>"
]
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_score": 1,
"_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": "4",
"_score": 1,
"_source": {
"title": "Solr in Action",
"authors": [
"trey grainger",
"timothy potter"
]
},
"highlight": {
"authors": [
"<em>trey</em> grainger",
"<em>timothy</em> potter"
]
}
}
]
正則查詢
正則查詢容許你指定比通配符查詢更復雜的查詢模式。
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": "4",
"_score": 1,
"_source": {
"title": "Solr in Action",
"authors": [
"trey grainger",
"timothy potter"
]
},
"highlight": {
"authors": [
"<em>trey</em> grainger",
"<em>timothy</em> potter"
]
}
}
]
匹配短語查詢
匹配短語查詢要求查詢字符串中的全部字詞都在文檔中存在，要遵循查詢字符串的指定順序還要彼此接近。默認狀況下，術語要求彼此相同，但你能夠指定slop值，進行文檔匹配時，該值能夠指定詞的距離。
POST /bookdb_index/book/_search
{
"query": {
"multi_match" : {
"query": "search engine",
"fields": ["title", "summary"],
"type": "phrase",
"slop": 3
}
},
"_source": [ "title", "summary", "publish_date" ]
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_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": "1",
"_score": 0.16113183,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]
注：在上述例子中，對於非短語類型查詢，文檔_id 1一般會以較高的權重出如今文檔_id 4以前，由於其字段長度更加短。然而，做爲短語查詢，術語的接近度也須要考慮在內，所以文檔_id 4權重會更高。
匹配短語前綴查詢
匹配短語前綴查詢在查詢時提供「自動搜索」功能（search-as-you-type）或者說詞窮時的自動補充功能，你無需以任何方式準備數據。和match_phrase查詢同樣，它接受slop參數，使得字的順序和相對位置的調整不那麼死板。它還接受max_expansions參數，以限制匹配的術語數量，減小資源強度。
POST /bookdb_index/book/_search
{
"query": {
"match_phrase_prefix" : {
"summary": {
"query": "search en",
"slop": 3,
"max_expansions": 10
}
}
},
"_source": [ "title", "summary", "publish_date" ]
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_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": "1",
"_score": 0.37248808,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]
注：查詢時（query-time）搜索類型具備性能成本。 因此你能夠選擇將索引時（index-time）搜索做爲搜索類型。更多詳情，請查看Completion Suggester API或使用Edge-Ngram filters獲取。
查詢字符串查詢
查詢字符串查詢提供了以簡明的速記語法執行multi_match查詢，bool查詢，boosting查詢，模糊匹配查詢，通配符查詢，regexp和範圍查詢的方法。下面示例中，我對「search algorithm」執行了模糊查詢，其中一本書的做者是「grant ingersoll」 或 「tom morton」，我對全部字段都進行查詢，但在summary字段，boost值設爲「2」。
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": "2",
"_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"
]
}
}
簡單查詢字符串查詢
簡單查詢字符串（simple_query_string）查詢是字符串（query_string）查詢的一個版本，更適合用戶在單個搜索框中使用。它分別用+ / | / - 替換AND / OR / NOT的使用，而且自動過濾掉查詢的無效部分，而不是在用戶犯錯誤時拋出異常。
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" : {}
}
}
}
術語查詢
以上都是全文搜索的例子。可是有些盆友對結構化搜索更感興趣，但願在其中找到徹底匹配並返回結果。這時，術語查詢即可以幫到咱們。在下面例子中，咱們將搜索Manning Publications出版的全部書籍。
POST /bookdb_index/book/_search
{
"query": {
"term" : {
"publisher": "manning"
}
},
"_source" : ["title","publish_date","publisher"]
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_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": "3",
"_score": 1.2231436,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_score": 1.2231436,
"_source": {
"publisher": "manning",
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
}
]
可使用術語關鍵字來指定多個術語，並傳入搜索術語數組。
{
"query": {
"terms" : {
"publisher": ["oreilly", "packt"]
}
}
}
術語查詢——排序
術語查詢結果（與全部其餘查詢結果同樣）能夠輕鬆排序， 也容許多級排序：
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": "3",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
},
"sort": [
1449100800000,
"in"
]
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Solr in Action",
"publish_date": "2014-04-05"
},
"sort": [
1396656000000,
"solr"
]
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_score": null,
"_source": {
"publisher": "manning",
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
},
"sort": [
1358985600000,
"to"
]
}
]
範圍查詢
另外一個結構化查詢示例是範圍查詢。 在此示例中，咱們將搜索在2015年出版的圖書：
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": "1",
"_score": 1,
"_source": {
"publisher": "oreilly",
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "3",
"_score": 1,
"_source": {
"publisher": "manning",
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
}
]
注：範圍查詢適用於日期，數字和字符串類型字段。
過濾查詢
過濾查詢容許您過濾查詢的結果。 例如，咱們要查詢標題或摘要中包含術語「Elasticsearch」的書籍，但要求結果過濾到包含20條以上評論的書。
POST /bookdb_index/book/_search
{
"query": {
"filtered": {
"query" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"range" : {
"num_reviews": {
"gte": 20
}
}
}
}
},
"_source" : ["title","summary","publisher", "num_reviews"]
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "1",
"_score": 0.5955761,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"publisher": "oreilly",
"num_reviews": 20,
"title": "Elasticsearch: The Definitive Guide"
}
}
]
注：過濾查詢不要求過濾的查詢的存在。若是沒有指定查詢，則運行match_all查詢，它基本上能返回索引中的全部文檔，而後對其進行過濾。 實際上，首先運行的是過濾器，這減小了須要查詢的面積。 此外，過濾器在第一次使用後緩存，這能使它更高效。
POST /bookdb_index/book/_search
{
"query": {
"bool": {
"must" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"range" : {
"num_reviews": {
"gte": 20
}
}
}
}
},
"_source" : ["title","summary","publisher", "num_reviews"]
}
這一樣適用於下面示例中的過濾器。
多項過濾器
多項過濾器能夠經過bool過濾器結合起來，在下一個示例中，過濾器指定返回的結果必須至少有20條評論，發佈時間在2015年以後，並應由oreilly發佈。
POST /bookdb_index/book/_search
{
"query": {
"filtered": {
"query" : {
"multi_match": {
"query": "elasticsearch",
"fields": ["title","summary"]
}
},
"filter": {
"bool": {
"must": {
"range" : { "num_reviews": { "gte": 20 } }
},
"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": "1",
"_score": 0.5955761,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"publisher": "oreilly",
"num_reviews": 20,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
}
]
函數權重：字段值要素
可能有這樣的狀況，您但願將文檔中特定字段的值考慮到相關性權重的計算中。 這在腳本中很常見，基於其受歡迎程度，你會但願boost文檔的相關性。 在咱們的例子中，咱們但願更受歡迎的書（根據評論的數量判斷）獲得boost。 這就可能使用到field_value_factor函數權重：
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" : 2
}
}
},
"_source": ["title", "summary", "publish_date", "num_reviews"]
}
[Results]
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "1",
"_score": 0.44831306,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": 20,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_score": 0.3718407,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": 23,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "3",
"_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": 18,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_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": 12,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
}
]
注1：咱們能夠只運行一個常規的multi_match查詢並按num_reviews字段排序，可是咱們失去了得到相關性分值的好處。
注2：有許多額外的參數在原始相關性權重上加強boost的程度，好比「modifier」， 「factor」，「boost_mode」等。這些在Elasticsearch指南中進行了詳細探討。
函數權重：關聯功能遞減函數
假設想要的不是讓某個字段值按某種關聯度遞增，而是想讓你關注的值按照同關聯度遞減。 這在基於lat / long，數字字段（如價格或日期）的boost中很是有用。 在下列示例中，咱們要在「搜索引擎」上搜索於2014年6月發佈的書籍。
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": "4",
"_score": 0.27420625,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": 23,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "1",
"_score": 0.005920768,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": 20,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_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": 12,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "3",
"_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": 18,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
}
]
函數權重: 腳本權重
在內置評分函數不能知足您的須要的狀況下，能夠選擇指定一個Groovy腳本用於評分。在咱們的示例中，咱們想要指定一個考慮發佈日期的腳本，而後再決定評論數，由於新出版的書可能沒有足夠的評論數。
權重腳本以下所示：
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(1 + num_reviews)
}
return my_score
要想動態使用權重腳本，咱們須要使用腳本權重參數：
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": 4,
"max_score": 0.8463001,
"hits": [
{
"_index": "bookdb_index",
"_type": "book",
"_id": "1",
"_score": 0.8463001,
"_source": {
"summary": "A distibuted real-time search and analytics engine",
"num_reviews": 20,
"title": "Elasticsearch: The Definitive Guide",
"publish_date": "2015-02-07"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "4",
"_score": 0.7067348,
"_source": {
"summary": "Comprehensive guide to implementing a scalable search engine using Apache Solr",
"num_reviews": 23,
"title": "Solr in Action",
"publish_date": "2014-04-05"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "3",
"_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": 18,
"title": "Elasticsearch in Action",
"publish_date": "2015-12-03"
}
},
{
"_index": "bookdb_index",
"_type": "book",
"_id": "2",
"_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": 12,
"title": "Taming Text: How to Find, Organize, and Manipulate It",
"publish_date": "2013-01-24"
}
}
]
}
注1：要使用動態腳本，必須在config / elasticsearch.yaml文件的Elasticsearch實例中激活。 固然，咱們也可使用存儲在Elasticsearch服務器上的腳本。 更多相關信息，請參閱Elasticsearch參考文檔。
注2：JSON不能包含嵌入的換行符，所以分號用來分隔語句。
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