elasticsearch中如何手动控制全文检索结果的精准度

1、为帖子数据增加标题字段

POST /forum/article/_bulk
{ "update": { "_id": "1"} }
{ "doc" : {"title" : "this is java and elasticsearch blog"} }
{ "update": { "_id": "2"} }
{ "doc" : {"title" : "this is java blog"} }
{ "update": { "_id": "3"} }
{ "doc" : {"title" : "this is elasticsearch blog"} }
{ "update": { "_id": "4"} }
{ "doc" : {"title" : "this is java, elasticsearch, hadoop blog"} }
{ "update": { "_id": "5"} }
{ "doc" : {"title" : "this is spark blog"} }

2、搜索标题中包含java或elasticsearch的blog

这个，就跟之前的那个term query，不一样了。不是搜索exact value，是进行full text全文检索。
match query，是负责进行全文检索的。当然，如果要检索的field，是not_analyzed类型的，那么match query也相当于term query。

GET /forum/article/_search
{
"query": {
　　"match": {
　　　　"title": "java elasticsearch"
　　　　}
　　}
}

3、搜索标题中包含java和elasticsearch的blog

搜索结果精准控制的第一步：灵活使用and关键字，如果你是希望所有的搜索关键字都要匹配的，那么就用and，可以实现单纯match query无法实现的效果

GET /forum/article/_search
{
    "query":{
        "match":{
            "title":{
                "query":"java elasticsearch",
                "operator":"and"
            }
        }
    }
}

4、搜索包含java，elasticsearch，spark，hadoop，4个关键字中，至少3个的blog

控制搜索结果的精准度的第二步：指定一些关键字中，必须至少匹配其中的多少个关键字，才能作为结果返回

GET /forum/article/_search
{
    "query":{
        "match":{
            "title":{
                "query":"java elasticsearch spark hadoop",
                "minimum_should_match":"75%"
            }
        }
    }
}

5、用bool组合多个搜索条件，来搜索title

GET /forum/article/_search
{
    "query":{
        "bool":{
            "must":{
                "match":{
                    "title":"java"
                }
            },
            "must_not":{
                "match":{
                    "title":"spark"
                }
            },
            "should":[
                {
                    "match":{
                        "title":"hadoop"
                    }
                },
                {
                    "match":{
                        "title":"elasticsearch"
                    }
                }
            ]
        }
    }
}

6、bool组合多个搜索条件，如何计算relevance score

must和should搜索对应的分数，加起来，除以must和should的总数

排名第一：java，同时包含should中所有的关键字，hadoop，elasticsearch
排名第二：java，同时包含should中的elasticsearch
排名第三：java，不包含should中的任何关键字

should是可以影响相关度分数的

must是确保说，谁必须有这个关键字，同时会根据这个must的条件去计算出document对这个搜索条件的relevance score
在满足must的基础之上，should中的条件，不匹配也可以，但是如果匹配的更多，那么document的relevance score就会更高

{
    "took":6,
    "timed_out":false,
    "_shards":{
        "total":5,
        "successful":5,
        "failed":0
    },
    "hits":{
        "total":3,
        "max_score":1.3375794,
        "hits":[
            {
                "_index":"forum",
                "_type":"article",
                "_id":"4",
                "_score":1.3375794,
                "_source":{
                    "articleID":"QQPX-R-3956-#aD8",
                    "userID":2,
                    "hidden":true,
                    "postDate":"2017-01-02",
                    "tag":[
                        "java",
                        "elasticsearch"
                    ],
                    "tag_cnt":2,
                    "view_cnt":80,
                    "title":"this is java, elasticsearch, hadoop blog"
                }
            },
            {
                "_index":"forum",
                "_type":"article",
                "_id":"1",
                "_score":0.53484553,
                "_source":{
                    "articleID":"XHDK-A-1293-#fJ3",
                    "userID":1,
                    "hidden":false,
                    "postDate":"2017-01-01",
                    "tag":[
                        "java",
                        "hadoop"
                    ],
                    "tag_cnt":2,
                    "view_cnt":30,
                    "title":"this is java and elasticsearch blog"
                }
            },
            {
                "_index":"forum",
                "_type":"article",
                "_id":"2",
                "_score":0.19856805,
                "_source":{
                    "articleID":"KDKE-B-9947-#kL5",
                    "userID":1,
                    "hidden":false,
                    "postDate":"2017-01-02",
                    "tag":[
                        "java"
                    ],
                    "tag_cnt":1,
                    "view_cnt":50,
                    "title":"this is java blog"
                }
            }
        ]
    }
}

7、搜索java，hadoop，spark，elasticsearch，至少包含其中3个关键字

默认情况下，should是可以不匹配任何一个的，比如上面的搜索中，this is java blog，就不匹配任何一个should条件
但是有个例外的情况，如果没有must的话，那么should中必须至少匹配一个才可以
比如下面的搜索，should中有4个条件，默认情况下，只要满足其中一个条件，就可以匹配作为结果返回

但是可以精准控制，should的4个条件中，至少匹配几个才能作为结果返回

GET /forum/article/_search
{
    "query":{
        "bool":{
            "should":[
                {
                    "match":{
                        "title":"java"
                    }
                },
                {
                    "match":{
                        "title":"elasticsearch"
                    }
                },
                {
                    "match":{
                        "title":"hadoop"
                    }
                },
                {
                    "match":{
                        "title":"spark"
                    }
                }
            ],
            "minimum_should_match":3
        }
    }
}