elasticsearch学习笔记高级篇（六）——在案例中如果通过手动控制全文检索结果的精准度

准备数据：

POST /forum/_bulk
{ "index": { "_id": 1 }}
{ "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden": false, "postDate": "2017-01-01" }
{ "index": { "_id": 2 }}
{ "articleID" : "KDKE-B-9947-#kL5", "userID" : 1, "hidden": false, "postDate": "2017-01-02" }
{ "index": { "_id": 3 }}
{ "articleID" : "JODL-X-1937-#pV7", "userID" : 2, "hidden": false, "postDate": "2017-01-01" }
{ "index": { "_id": 4 }}
{ "articleID" : "QQPX-R-3956-#aD8", "userID" : 2, "hidden": true, "postDate": "2017-01-02" }

1、为帖子数据增加标题字段

POST /forum/_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 filter/query不一样了。不是搜索exact value，而是进行full text全文搜索。

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/_search
{
  "query": {
    "match": {
      "title": "java elasticsearch"
    }
  }
}

{
  "took" : 1139,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 4,
      "relation" : "eq"
    },
    "max_score" : 0.97797304,
    "hits" : [
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 0.97797304,
        "_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" : "_doc",
        "_id" : "4",
        "_score" : 0.97797304,
        "_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" : "_doc",
        "_id" : "2",
        "_score" : 0.57843524,
        "_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"
        }
      },
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 0.57843524,
        "_source" : {
          "articleID" : "JODL-X-1937-#pV7",
          "userID" : 2,
          "hidden" : false,
          "postDate" : "2017-01-01",
          "tag" : [
            "hadoop"
          ],
          "tag_cnt" : 1,
          "view_cnt" : 100,
          "title" : "this is elasticsearch blog"
        }
      }
    ]
  }
}

3、搜索标题中包含java和elasticsearch的blog

搜索结果精确控制的第一步就是灵活使用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/_search
{
  "query": {
    "match": {
      "title": {
        "query": "java elasticsearch",
        "operator": "and"
      }
    }
  }
}

{
  "took" : 6,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 0.97797304,
    "hits" : [
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 0.97797304,
        "_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" : "_doc",
        "_id" : "4",
        "_score" : 0.97797304,
        "_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"
        }
      }
    ]
  }
}

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

控制搜索结果的精确度的第二步就是指定一些关键字中，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/_search
{
  "query": {
    "match": {
      "title": {
        "query": "java elasticsearch spark hadoop",
        "minimum_should_match": 3
      }
    }
  }
}

{
  "took" : 4,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 2.2356422,
    "hits" : [
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 2.2356422,
        "_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"
        }
      }
    ]
  }
}

5、用bool组合多个搜索条件，来搜索title

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

{
  "took" : 12,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 3,
      "relation" : "eq"
    },
    "max_score" : 2.2356422,
    "hits" : [
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 2.2356422,
        "_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" : "_doc",
        "_id" : "1",
        "_score" : 0.97797304,
        "_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" : "_doc",
        "_id" : "2",
        "_score" : 0.57843524,
        "_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"
        }
      }
    ]
  }
}

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的总分数

所以排在第一位的是：包含java、hadoop、elasticsearch

排在第二位的是：包含java、elasticsearch

排在第三位的是：包含java

should是可以影响相关度分数的

must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的基础上，should中的条件，不匹配也是可以的，但是如果匹配的更多，那么document的relevance score就会更高。

7、should实现搜索四个关键字中至少包含三个关键字

默认情况下，should是可以不匹配任何一个的，但是有一个例外的情况，就是如果没有must的情况下，那么should中必须至少匹配一个才可以

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

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 2.2356422,
    "hits" : [
      {
        "_index" : "forum",
        "_type" : "_doc",
        "_id" : "4",
        "_score" : 2.2356422,
        "_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"
        }
      }
    ]
  }
}