elasticsearch|Elasticsearch-18.综合排序:Function Score Query 优化算分和Term&PhraseSuggester 搜索引擎|经验分享|数据分析

Elasticsearch 综合排序:Function Score Query 优化算分算分与排序

Elasticsearch 默认会以文档的相关度算分进行排序
可以通过指定一个或者多个字段进行排序
使用相关度算分(score)排序，不能满足某些特定条件
- 无法针对相关度，对排序实现更多的控制

Function Score Query

Function Score Query
- 可以在查询结束后，对每一个匹配的文档进行一系列的重新算分，根据新生成的分数进行排序。
提供了几种默认的计算分值的函数
- Weight :为每-个文档设置-个简单而不被规范化的权重
- Field Value Factor:使用该数值来修改_ score, 例如将“ 热度”和‘点赞数”作为算分的参考因素
- Random Score:为每- -个用户使用一个不同的，随机算分结果
- 衰减函数:以某个字段的值为标准，距离某个值越近，得分越高
- Script Score:自定义脚本完全控制所需逻辑

按受欢迎度提升权重

elasticsearch|Elasticsearch-18.综合排序:Function Score Query 优化算分和Term&PhraseSuggester

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使用Modifier平滑曲线

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引入Factor

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Boost Mode和Max Boost

Boost Mode
- Multiply: 算分与函数值的乘积
- Sum: 算分与函数的和
- Min/ Max: 算分与函数取最小/最大值.
- Replace: 使用函数值取代算分
Max Boost可以将算分控制在一个最大值

致性随机函数

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API

DELETE blogs PUT /blogs/_doc/1 { "title":"About popularity", "content": "In this post we will talk about...", "votes":0 }PUT /blogs/_doc/2 { "title":"About popularity", "content": "In this post we will talk about...", "votes":100 }PUT /blogs/_doc/3 { "title":"About popularity", "content": "In this post we will talk about...", "votes":1000000 }POST /blogs/_search { "query": { "function_score": { "query": { "multi_match": { "query":"popularity", "fields": [ "title", "content" ] } }, "field_value_factor": { "field": "votes" } } } }POST /blogs/_search { "query": { "function_score": { "query": { "multi_match": { "query":"popularity", "fields": [ "title", "content" ] } }, "field_value_factor": { "field": "votes", "modifier": "log1p" } } } }POST /blogs/_search { "query": { "function_score": { "query": { "multi_match": { "query":"popularity", "fields": [ "title", "content" ] } }, "field_value_factor": { "field": "votes", "modifier": "log1p" , "factor": 0.1 } } } }POST /blogs/_search { "query": { "function_score": { "query": { "multi_match": { "query":"popularity", "fields": [ "title", "content" ] } }, "field_value_factor": { "field": "votes", "modifier": "log1p" , "factor": 0.1 }, "boost_mode": "sum", "max_boost": 3 } } }POST /blogs/_search { "query": { "function_score": { "random_score": { "seed": 911119 } } } }

知识点回顾

复合查询: Function Score Query
- 提供了多种函数，自定义脚本，完全控制算分
Field Value Factor:搜索的相关度,能够结合投票的数量进行重算。通过一些参数的设
定，对算分进行控制
随机函数: 用户提供Seed,返回一个随机一致性的排序结果

Term&PhraseSuggester 什么是搜索建议

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Elasticsearch Suggester API

搜索引擎中类似的功能，在Elasticsearch中是通过Suggester API实现的
原理: 将输入的文本分解为Token，然后在索引的字典里查找相似的Term并返回
根据不同的使用场景， Elasticsearch 设计了4种类别的Suggesters
- Term & Phrase Suggester
- Complete & Context Suggester

Term Suggester

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一些测试数据

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Term Suggester一Missing Mode

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Term Suggester一Popular Mode

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Sorting by Frequency & Prefix L ength

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Phrase Suggester
【elasticsearch|Elasticsearch-18.综合排序:Function Score Query 优化算分和Term&PhraseSuggester】

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API

DELETE articles PUT articles { "mappings": { "properties": { "title_completion":{ "type": "completion" } } } }POST articles/_bulk { "index" : { } } { "title_completion": "lucene is very cool"} { "index" : { } } { "title_completion": "Elasticsearch builds on top of lucene"} { "index" : { } } { "title_completion": "Elasticsearch rocks"} { "index" : { } } { "title_completion": "elastic is the company behind ELK stack"} { "index" : { } } { "title_completion": "Elk stack rocks"} { "index" : {} }POST articles/_search?pretty { "size": 0, "suggest": { "article-suggester": { "prefix": "elk ", "completion": { "field": "title_completion" } } } }DELETE articlesPOST articles/_bulk { "index" : { } } { "body": "lucene is very cool"} { "index" : { } } { "body": "Elasticsearch builds on top of lucene"} { "index" : { } } { "body": "Elasticsearch rocks"} { "index" : { } } { "body": "elastic is the company behind ELK stack"} { "index" : { } } { "body": "Elk stack rocks"} { "index" : {} } {"body": "elasticsearch is rock solid"}POST _analyze { "analyzer": "standard", "text": ["Elk stackrocks rock"] }POST /articles/_search { "size": 1, "query": { "match": { "body": "lucen rock" } }, "suggest": { "term-suggestion": { "text": "lucen rock", "term": { "suggest_mode": "missing", "field": "body" } } } }POST /articles/_search {"suggest": { "term-suggestion": { "text": "lucen rock", "term": { "suggest_mode": "popular", "field": "body" } } } }POST /articles/_search {"suggest": { "term-suggestion": { "text": "lucen rock", "term": { "suggest_mode": "always", "field": "body", } } } }POST /articles/_search {"suggest": { "term-suggestion": { "text": "lucen hocks", "term": { "suggest_mode": "always", "field": "body", "prefix_length":0, "sort": "frequency" } } } }POST /articles/_search { "suggest": { "my-suggestion": { "text": "lucne and elasticsear rock hello world ", "phrase": { "field": "body", "max_errors":2, "confidence":0, "direct_generator":[{ "field":"body", "suggest_mode":"always" }], "highlight": { "pre_tag": "", "post_tag": "" } } } } }

知识点回顾