文章目录
概述boost示例概述
继续跟中华石杉老师学习ES，第八篇
课程地址： /view/55
boost
https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-boost.html
知识点：
如果给某个字段设置boost 为2 ，则意味着改字段的权重比其他的值的权重大一倍 。权重值默认为1
The boost is applied only for term queries (prefix, range and fuzzy queries are not boosted).
示例
数据如下：
{"_index": "forum","_type": "article","_id": "5","_score": 1,"_source": {"articleID": "DHJK-B-1395-#Ky5","userID": 3,"hidden": false,"postDate": "-05-01","tag": ["elasticsearch"],"tag_cnt": 1,"view_cnt": 10,"title": "this is spark blog"}},{"_index": "forum","_type": "article","_id": "2","_score": 1,"_source": {"articleID": "KDKE-B-9947-#kL5","userID": 1,"hidden": false,"postDate": "-01-02","tag": ["java"],"tag_cnt": 1,"view_cnt": 50,"title": "this is java blog"}},{"_index": "forum","_type": "article","_id": "4","_score": 1,"_source": {"articleID": "QQPX-R-3956-#aD8","userID": 2,"hidden": true,"postDate": "-01-02","tag": ["java","elasticsearch"],"tag_cnt": 2,"view_cnt": 80,"title": "this is java, elasticsearch, hadoop blog"}},{"_index": "forum","_type": "article","_id": "1","_score": 1,"_source": {"articleID": "XHDK-A-1293-#fJ3","userID": 1,"hidden": false,"postDate": "-01-01","tag": ["java","hadoop"],"tag_cnt": 2,"view_cnt": 30,"title": "this is java and elasticsearch blog"}},{"_index": "forum","_type": "article","_id": "3","_score": 1,"_source": {"articleID": "JODL-X-1937-#pV7","userID": 2,"hidden": false,"postDate": "-01-01","tag": ["hadoop"],"tag_cnt": 1,"view_cnt": 100,"title": "this is elasticsearch blog"}}
需求： 搜索标题中必须包含blog的帖子，同时如果标题中包含java或elasticsearch或hadoop或spark也要搜索出来，同时如果一个帖子包含spark，包含spark的帖子要优先其他帖子搜索出来
需求实现DSL如下：
GET /forum/article/_search{"query": {"bool": {"must": {"match": {"title": "blog"}},"should": [{"match": {"title": {"query": "java"}}},{"match": {"title": {"query": "elasticsearch"}}},{"match": {"title": {"query": "hadoop"}}},{"match": {"title": {"query": "spark","boost": 5}}}]}}}
返回结果 ：
{"took": 5,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 5,"max_score": 1.7260925,"hits": [{"_index": "forum","_type": "article","_id": "5","_score": 1.7260925,"_source": {"articleID": "DHJK-B-1395-#Ky5","userID": 3,"hidden": false,"postDate": "-05-01","tag": ["elasticsearch"],"tag_cnt": 1,"view_cnt": 10,"title": "this is spark blog"}},{"_index": "forum","_type": "article","_id": "4","_score": 1.6185135,"_source": {"articleID": "QQPX-R-3956-#aD8","userID": 2,"hidden": true,"postDate": "-01-02","tag": ["java","elasticsearch"],"tag_cnt": 2,"view_cnt": 80,"title": "this is java, elasticsearch, hadoop blog"}},{"_index": "forum","_type": "article","_id": "1","_score": 0.8630463,"_source": {"articleID": "XHDK-A-1293-#fJ3","userID": 1,"hidden": false,"postDate": "-01-01","tag": ["java","hadoop"],"tag_cnt": 2,"view_cnt": 30,"title": "this is java and elasticsearch blog"}},{"_index": "forum","_type": "article","_id": "3","_score": 0.5753642,"_source": {"articleID": "JODL-X-1937-#pV7","userID": 2,"hidden": false,"postDate": "-01-01","tag": ["hadoop"],"tag_cnt": 1,"view_cnt": 100,"title": "this is elasticsearch blog"}},{"_index": "forum","_type": "article","_id": "2","_score": 0.3971361,"_source": {"articleID": "KDKE-B-9947-#kL5","userID": 1,"hidden": false,"postDate": "-01-02","tag": ["java"],"tag_cnt": 1,"view_cnt": 50,"title": "this is java blog"}}]}}
可以看到spark的帖子，相关度得分最高，排在了第一位。
搜索条件的权重，boost，可以将某个搜索条件的权重加大，此时当匹配这个搜索条件和匹配另一个搜索条件的document，计算relevance score时，匹配权重更大的搜索条件的document，relevance score会更高，当然也就会优先被返回回来
我们如果把boost去掉会怎样呢？ 来看下
GET /forum/article/_search{"query": {"bool": {"must": {"match": {"title": "blog"}},"should": [{"match": {"title": {"query": "java"}}},{"match": {"title": {"query": "elasticsearch"}}},{"match": {"title": {"query": "hadoop"}}},{"match": {"title": {"query": "spark"}}}]}}}
返回：
{"took": 11,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 5,"max_score": 1.6185135,"hits": [{"_index": "forum","_type": "article","_id": "4","_score": 1.6185135,"_source": {"articleID": "QQPX-R-3956-#aD8","userID": 2,"hidden": true,"postDate": "-01-02","tag": ["java","elasticsearch"],"tag_cnt": 2,"view_cnt": 80,"title": "this is java, elasticsearch, hadoop blog"}},{"_index": "forum","_type": "article","_id": "1","_score": 0.8630463,"_source": {"articleID": "XHDK-A-1293-#fJ3","userID": 1,"hidden": false,"postDate": "-01-01","tag": ["java","hadoop"],"tag_cnt": 2,"view_cnt": 30,"title": "this is java and elasticsearch blog"}},{"_index": "forum","_type": "article","_id": "5","_score": 0.5753642,"_source": {"articleID": "DHJK-B-1395-#Ky5","userID": 3,"hidden": false,"postDate": "-05-01","tag": ["elasticsearch"],"tag_cnt": 1,"view_cnt": 10,"title": "this is spark blog"}},{"_index": "forum","_type": "article","_id": "3","_score": 0.5753642,"_source": {"articleID": "JODL-X-1937-#pV7","userID": 2,"hidden": false,"postDate": "-01-01","tag": ["hadoop"],"tag_cnt": 1,"view_cnt": 100,"title": "this is elasticsearch blog"}},{"_index": "forum","_type": "article","_id": "2","_score": 0.3971361,"_source": {"articleID": "KDKE-B-9947-#kL5","userID": 1,"hidden": false,"postDate": "-01-02","tag": ["java"],"tag_cnt": 1,"view_cnt": 50,"title": "this is java blog"}}]}}
spark的帖子并没有优先展示出来 ，可见boost权重确实起了作用。
如果觉得《白话Elasticsearch08-深度探秘搜索技术之基于boost的细粒度搜索条件权重控制》对你有帮助，请点赞、收藏，并留下你的观点哦！
