如何防止Elasticsearch仅匹配一个非英文字符与multi_match

Question

我使用的是elasiticsearch-dsl和SmartCN分析器：

from elasticsearch_dsl import analyzer
analyzer_cn = analyzer(
    'smartcn',
    tokenizer=tokenizer('smartcn_tokenizer'),
    filter=['lowercase']
)

我使用multi_match在几个术语上进行匹配：

from elasticsearch_dsl import Q
q_new = Q("multi_match", query="SOME_QUERY", fields=["FEIDL_NAME"])

期望的行为是ES只返回至少有两个字符匹配的文档。我浏览了所有文档，但找不到阻止Elasticsearch匹配单个字符的方法。

任何方向/建议都是非常感谢的。谢谢。

Answer 1

期望的行为是ES只返回至少有两个字符匹配的文档。

我不熟悉SmartCN analyzer，但是如果你想匹配至少2个字符，那么根据你的用例，你可以使用N-gram tokenizer，当它遇到指定字符列表中的一个时，它首先将文本分解为单词，然后它发出指定长度的每个单词的N-gram。

索引映射：

{
    "settings": {
        "analysis": {
            "analyzer": {
                "my_analyzer": {
                    "tokenizer": "my_tokenizer"
                }
            },
            "tokenizer": {
                "my_tokenizer": {
                    "type": "ngram",
                    "min_gram": 2,    <-- note this
                    "max_gram": 20,
                    "token_chars": [
                        "letter",
                        "digit"
                    ]
                }
            }
        },
        "max_ngram_diff": 50
    },
    "mappings": {
        "properties": {
            "title": {
                "type": "text",
                "analyzer": "my_analyzer",
                "search_analyzer": "standard"
            }
        }
    }
}

索引数据：

{
    "title": "world"
}

分析应用编程接口

搜索查询将不匹配"title": "w"，因为生成的令牌的最小长度为2(因为上面的索引映射中将min_gram定义为2)

生成的令牌包括：

POST/_analyze

{
  "tokens": [
    {
      "token": "wo",
      "start_offset": 0,
      "end_offset": 2,
      "type": "word",
      "position": 0
    },
    {
      "token": "wor",
      "start_offset": 0,
      "end_offset": 3,
      "type": "word",
      "position": 1
    },
    {
      "token": "worl",
      "start_offset": 0,
      "end_offset": 4,
      "type": "word",
      "position": 2
    },
    {
      "token": "world",
      "start_offset": 0,
      "end_offset": 5,
      "type": "word",
      "position": 3
    },
    {
      "token": "or",
      "start_offset": 1,
      "end_offset": 3,
      "type": "word",
      "position": 4
    },
    {
      "token": "orl",
      "start_offset": 1,
      "end_offset": 4,
      "type": "word",
      "position": 5
    },
    {
      "token": "orld",
      "start_offset": 1,
      "end_offset": 5,
      "type": "word",
      "position": 6
    },
    {
      "token": "rl",
      "start_offset": 2,
      "end_offset": 4,
      "type": "word",
      "position": 7
    },
    {
      "token": "rld",
      "start_offset": 2,
      "end_offset": 5,
      "type": "word",
      "position": 8
    },
    {
      "token": "ld",
      "start_offset": 3,
      "end_offset": 5,
      "type": "word",
      "position": 9
    }
  ]
}

**Search Query:**

    {
        "query": {
            "match": {
                "title": "wo"
            }
        }
    }

搜索结果：

"hits": [
      {
        "_index": "stof_64003025",
        "_type": "_doc",
        "_id": "2",
        "_score": 0.56802315,
        "_source": {
          "title": "world"
        }
      }
    ]