ElasticSearch 單字符串多字段查詢評分問題

1. 學習查詢的api語法

   首先向es中titles寫入兩個文檔

  

POST titles/_doc/1
{
  "title": "Quick brown rabbits",
  "body": "Brown rabbits are commonly seen."
}

POST titles/_doc/2
{
   "title": "Keeping pets healthy",
   "body": "My quick brown fox eats rabbits on a regular basis."
}

2 . 查詢 tille 和body中 全文檢索 quick brown的內容,語法如下

   1. 首先在寫入文檔的時候會先對寫入的內容進行分詞,分詞后寫入倒排索引,查詢的時候也會對查詢內容進行分詞,分詞后和倒排索引進行匹配，進行相關度查詢

POST titles/_search
{
  "query": {
    "bool": {
      "should": [
        {"match": {"title": "quick brown"}},
        {"match": {"body": "quick brown"}}
      ]
    }
  }  
}

　結果如下 

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 2.1213155,
    "hits" : [
      {
        "_index" : "titles",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 2.1213155,
        "_source" : {
          "title" : "Quick brown rabbits",
          "body" : "Brown rabbits are commonly seen."
        }
      },
      {
        "_index" : "titles",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 0.55788946,
        "_source" : {
          "title" : "Keeping pets healthy",
          "body" : "My quick brown fox eats rabbits on a regular basis."
        }
      }
    ]
  }
}

　　可以看到查詢結果, 匹配到兩個文檔，文檔1的評分比文檔2的評分要高，直觀感受應該是文檔2的評分更匹配，這是因為should 查詢評分是疊加的關系，會對body 和titile 中查詢字段評分進行疊加  1，中body和title 中都有brown

      2 中的titile沒有匹配，雖然body內容更加匹配。 有時候我們需要查詢某個字段更加匹配展示給用戶，可以使用dis_max 查詢 

     

POST titles/_search
{
  "query": {
    "multi_match": {
      "query": "brown fox",
      "fields": ["title","body"],
      "type": "best_fields",
      "tie_breaker": 0.2
    }
  }
}

　　說明下 ，tile_breaker 是對除了最匹配的字段外,提升其他字段的權重得分.默認是0 也就是除了最匹配外，其他字段都忽略。 

   查詢結果如下,可以看到文檔2的評分比文檔1高,查詢也可以修改字段的權重，title^10 標識把title查詢的權重提升10倍。 默認title和body的權重是一樣的。 這個可以根據實際業務來看

  

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 0.77041256,
    "hits" : [
      {
        "_index" : "titles",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 0.77041256,
        "_source" : {
          "title" : "Keeping pets healthy",
          "body" : "My quick brown fox eats rabbits on a regular basis."
        }
      },
      {
        "_index" : "titles",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 0.735369,
        "_source" : {
          "title" : "Quick brown rabbits",
          "body" : "Brown rabbits are commonly seen."
        }
      }
    ]
  }
}

　　

 

參考： Elasticsearch核心技術與實戰