Elasticsearch ngram 查询不起作用答案

【问题标题】：Elasticsearch ngram query doesn't workElasticsearch ngram 查询不起作用
【发布时间】：2017-07-08 17:49:02
【问题描述】：

我从 elasticsearch 2.0 迁移到 5.2，现在 ngram 搜索被破坏了！

elasticsearch 设置就在下面，它只是一个简单的用于标题和摘要字段的 ngram 标记器。

settings = {
    "settings": {
        "number_of_shards": 1,
        "number_of_replicas": 0,
        "analysis": {
            "filter": {
                "ngram_filter": {
                    "type": "nGram",
                    "min_gram": 3,
                    "max_gram": 10
                }
            },
            "analyzer": {
                "search_ngram_analyzer": {
                    "tokenizer": "standard",
                    "type": "custom",
                    "filter": ["standard", "lowercase", "stop", "asciifolding"]
                },

                "index_ngram_analyzer": {
                    "tokenizer": "standard",
                    "type": "custom",
                    "filter": ["standard", "lowercase", "stop", "asciifolding", "ngram_filter"]
                }
            }
        },

    },
    "mappings": {
        "docs": {
            "properties": {
                'title': {
                    'boost': 100.0,
                    'search_analyzer': 'search_ngram_analyzer',
                    'analyzer': 'index_ngram_analyzer',
                    'type': 'text',
                },
                'summary': {
                    'boost': 20.0,
                    'search_analyzer': 'search_ngram_analyzer',
                    'analyzer': 'index_ngram_analyzer',
                    'type': 'text',
                }
            }
        }

    }
}

http://localhost:9200/my_index/_search?q=example 返回包含单词“example”的文档。作为普通查询。

然而， http://localhost:9200/my_index/_search?q=exampl（以“e”为例）返回一个空对象！

我在我的设置中没有发现错误。这是 API 中断吗？

【问题讨论】：

标签： elasticsearch

【解决方案1】：

您确定这在以前的版本中有效吗？

如果您使用 URI 搜索并且未指定字段（就像您在 http://localhost:9200/my_index/_search?q=exampl 中所做的那样），则将使用 _all 字段。它使用标准分析器，因此没有 ngram。您要使用的查询是/my_index/_search?q=title:exampl

为了重现性，这里是控制台整个示例的转储：

PUT /my_index
{
  "settings": {
    "analysis": {
      "filter": {
        "ngram_filter": {
          "type": "nGram",
          "min_gram": 3,
          "max_gram": 10
        }
      },
      "analyzer": {
        "search_ngram_analyzer": {
          "tokenizer": "standard",
          "type": "custom",
          "filter": [
            "standard",
            "lowercase",
            "stop",
            "asciifolding"
          ]
        },
        "index_ngram_analyzer": {
          "tokenizer": "standard",
          "type": "custom",
          "filter": [
            "standard",
            "lowercase",
            "stop",
            "asciifolding",
            "ngram_filter"
          ]
        }
      }
    }
  },
  "mappings": {
    "docs": {
      "properties": {
        "title": {
          "boost": 100,
          "search_analyzer": "search_ngram_analyzer",
          "analyzer": "index_ngram_analyzer",
          "type": "text"
        },
        "summary": {
          "boost": 20,
          "search_analyzer": "search_ngram_analyzer",
          "analyzer": "index_ngram_analyzer",
          "type": "text"
        }
      }
    }
  }
}


GET /my_index/_analyze
{
  "analyzer": "index_ngram_analyzer",
  "text": "example exampl"
}
GET /my_index/_analyze
{
  "analyzer": "search_ngram_analyzer",
  "text": "example exampl"
}

POST /my_index/docs
{
  "title": "This is an example",
  "summary": "Some more text"
}

GET /my_index/_search?q=example
GET /my_index/_search?q=exampl
GET /my_index/_search?q=title:exampl

DELETE /my_index

【讨论】：