在弹性搜索中查询以检索以特定单词开头的字符串 [英] Query in Elasticsearch for retrieving strings that start with a particular word

问题描述

我想在弹性搜索中编写一个查询，这样它只会给出字符串从特定单词开始的结果，例如我现在有一个字符串Donald Duck，另一个字符串是Alan Donald，如果我会搜索对于Donald，以下查询

 query：{
 query_string：{
 query： Donald，
字段：['character_name'] 
} 
} 
  

那么结果应该是唐老鸭，而不是艾伦唐纳德，因为在唐老鸭它以唐纳德开头。现在有人可以告诉我如何写这样一个查询，我搜索了很多帖子，但没有找到任何解决方案。

Edit-1

我的映射在下面给出

 设置：{
 index：{
analysis：{
analyzer：{
simple_wildcard：{
tokenizer：whitespace，
 ：[smallcase] 
} 
} 
} 
} 
}，
mappings：{
college {
properties：{
character_name：{type：string，index：analyze，analyzer：simple_wildcard} 
 
} 
} 
} 
  

解决方案

限制令牌过滤器将非常有用。您可以以两种不同的方式分析 character_name 字段，一种用于标准搜索操作，另一种用于获取以特定单词开头的字符串。我创建了这样的示例索引。 only_first 仅索引字符串的第一个标记。

  PUT字符
 {
settings：{
analysis：{
analyzer：{
character_analyzer：{
tokenizer：whitespace，
 filter：[
smallcase，
one_token_limit
] 
} 
}，
filter：{
 one_token_limit：{
type：limit，
max_token_count：1 
} 
} 
} 
}，
 mappings：{
mytype：{
properties：{
character_name：{
type：string，
 ：{
only_first：{
type：string，
analyzer：character_analyzer
} 
} 
} 
} 
} 
} 
} 
  

然后你好在 only_first 字段中，这样

  {
query：{
query_string：{
fields：[character_name.only_first]，
query：Donald
} 
} 
} 
  

这将给您所需的结果。我已经使用空格标记器，但你如果你想要匹配唐纳德·唐纳德鸭，也可以去标准的标记器。

另一种方法是跨第一个查询，但问题是它是一个术语查询所以'唐纳德'将匹配，但'唐纳德'不匹配

  {
 span_first：{
match：{
span_term：{character_name：donald} 
}，
end：1 
} 
} 
  

但是唐纳德将给你零结果（区分大小写），但第一种方法肯定会起作用。

编辑1 ：前缀匹配

您可以在span fi内包装前缀查询rst like this

  {
query：{
span_first：{
 match：{
span_multi：{
match：{
prefix：{
character_name：{
value 
} 
} 
} 
} 
}，
结束：1 
} 
} 
} 
  

不要使用*在查询中。

希望它有帮助！

I want to write a query in elasticsearch such that it will only give results where string starts from a particular word for example i have one string "Donald Duck" and the other string which is "Alan Donald" now if i will search for "Donald" with below query

"query": {
     query_string: {
         query: "Donald",
         fields: ['character_name']
     }
 }

then result should be "Donald Duck" not "Alan Donald" because in "Donald Duck" it starts with "Donald". Now can anyone please tell me how can i write such a query, i have searched a lot of posts but haven't found any solution.

Edit-1

My mapping is given below

"settings": {
        "index": {
                "analysis": {
                    "analyzer": {
                        "simple_wildcard": {
                    "tokenizer": "whitespace",
                    "filter": ["lowercase"]
                        }
                    }
                }
            }
      },
      "mappings" : {
        "college": {
                "properties":{
                    "character_name" : { "type" : "string", "index": "analyzed", "analyzer": "simple_wildcard"}

                }
            }
}

解决方案

Limit Token filter would be very helpful in this particular case. You can analyze character_name field in two different ways, one for standard search operations and other to get the string starting with particular word. I created the sample index like this. only_first indexes only the first token of the string.

PUT character
{
  "settings": {
    "analysis": {
      "analyzer": {
        "character_analyzer": {
          "tokenizer": "whitespace",
          "filter": [
            "lowercase",
            "one_token_limit"
          ]
        }
      },
      "filter": {
        "one_token_limit": {
          "type": "limit",
          "max_token_count": 1
        }
      }
    }
  },
  "mappings": {
    "mytype": {
      "properties": {
        "character_name": {
          "type": "string",
          "fields": {
            "only_first": {
              "type": "string",
              "analyzer": "character_analyzer"
            }
          }
        }
      }
    }
  }
}

Then you query on the only_first field like this

{
  "query": {
    "query_string": {
      "fields": ["character_name.only_first"],
      "query": "Donald"
    }
  }
}

This will give you the desired results. I have used whitespace tokenizer but you can also go for standard tokenizer if you want to match "donald-donald duck".

Another way is span first query but the problem is it is a term query so 'donald' will match but 'Donald' wont match

{
    "span_first" : {
        "match" : {
            "span_term" : { "character_name" : "donald" }
        },
        "end" : 1
    }
}

But 'Donald' will give you zero results(case sensitive), but the first approach will definitely work.

EDIT 1 : Prefix Match

You can wrap prefix query inside span first like this

{
  "query": {
    "span_first": {
      "match": {
        "span_multi": {
          "match": {
            "prefix": {
              "character_name": {
                "value": "don"
              }
            }
          }
        }
      },
      "end": 1
    }
  }
}

Do not use "*" in query.

Hope it helps!

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