大型文本字段上的 Elasticsearch 自动完成

Question

我使用的是 ES 7.x 版本，基本上要求是在具有文件/文档内容的大文本字段上提供自动建议/提前输入。

我已经探索了多种方法，如果我限制使用 _source，它会返回整个源文档或特定字段。我已经尝试过边缘 ngram 或 n-gram 标记器、前缀查询、完成建议器。

以下是示例文档（内容字段可能有 1000 多个句子）：

{
    "content":"Elasticsearch is a distributed, free and open search and analytics engine for all types of data, including textual, numerical, geospatial, structured, and unstructured. 
Elasticsearch is built on Apache Lucene and was first released in 2010 by Elasticsearch N.V. (now known as Elastic). 
Known for its simple REST APIs, distributed nature, speed, and scalability, Elasticsearch is the central component of the Elastic Stack, a set of free and open tools for data ingestion, enrichment, storage, analysis, and visualization. Commonly referred to as the ELK Stack (after Elasticsearch, Logstash, and Kibana), 
the Elastic Stack now includes a rich collection of lightweight shipping agents known as Beats for sending data to Elasticsearch."
}

以下是预期输出：

搜索查询： el

输出：["elasticsearch","elastic","elk"]

搜索查询：分析电子

输出：[“分析引擎”]

目前我无法使用 OOTB 功能实现上述输出。因此，我使用了弹性搜索的突出显示功能并在结果上应用了正则表达式，并使用 Java 创建了唯一的建议列表。

下面是我目前使用高亮功能的实现。

索引映射：

PUT index
{
  "settings": {
    "index": {
      "number_of_shards": 2,
      "number_of_replicas": 1
    },
    "analysis": {
      "filter": {
        "stop_filter": {
          "type": "stop",
          "stopwords": "_english_"
        },
        "ngram_filter": {
          "token_chars": [
            "letter",
            "digit",
            "symbol",
            "punctuation"
          ],
          "min_gram": "1",
          "type": "edge_ngram",
          "max_gram": "12"
        }
      },
      "analyzer": {
        "text_english": {
          "type": "custom",
          "tokenizer": "uax_url_email",
          "filter": [
            "lowercase",
            "stop_filter"
          ]
        },
        "whitespace_analyzer": {
          "filter": [
            "lowercase"
          ],
          "type": "custom",
          "tokenizer": "whitespace"
        },
        "ngram_analyzer": {
          "filter": [
            "lowercase",
            "stop_filter",
            "ngram_filter"
          ],
          "type": "custom",
          "tokenizer": "letter"
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "content": {
        "type": "text",
        "fields": {
          "autocorrect": {
            "type": "text",
            "analyzer": "ngram_analyzer",
            "search_analyzer": "whitespace_analyzer"
          }
        },
        "analyzer": "text_english"
      }
    }
  }
}

下面是从 Java 执行的 Elasticsearch 查询

POST autosuggest/_search
{
  "_source": "content.autocorrect",
  "query": {
    "match_phrase": {
      "content.autocorrect": "analytics e"
    }
  },
  "highlight": {
    "fields": {
      "content.autocorrect": {
        "fragment_size": 500,
        "number_of_fragments": 1
      }
    }
  }
}

我们在上面的查询结果中应用了正则表达式模式。

如果没有上述解决方法，请告诉我是否有任何方法可以实现。

Answer 1

完成建议器不是适合您的用例的工具。同样，根据您拥有的内容量，ngram 和边缘 ngram 可能会过大。

您是否尝试过match_phrase_prefix query，它将完整的标记一个一个地匹配，最后一个作为前缀？

下面的查询非常简单，应该可以按您预期的方式工作。

POST test/_search
{
  "query": {
    "match_phrase_prefix": {
      "content": "analytics e"
    }
  }
}