Elasticsearch-2.4.x > Mapping > Meta-fields > _field_names

_field_names field

_field_names字段索引文档中包含除null之外的任何值的每个字段的名称,该字段用于exists和missing查询使用,用于查找对指定字段具有或没有任何non-null值的文档.
在查询,聚合和脚本中可以访问_field_name字段的值:

# Example documents
PUT my_index/my_type/1
{
  "title": "This is a document"
}

PUT my_index/my_type/1
{
  "title": "This is another document",
  "body": "This document has a body"
}

GET my_index/_search
{
  "query": {
    "terms": {
      "_field_names": [ "title" ]                                                    (1)
    }
  },
  "aggs": {
    "Field names": {
      "terms": {
        "field": "_field_names",                                                     (2)
        "size": 10
      }
    }
  },
  "script_fields": {
    "Field names": {
      "script": "doc['_field_names']"                                                (3)
    }
  }
}

(1) 在_field_names字段上查询
(2) 在_field_names字段上聚合
(3) 在脚本中访问_field_names字段

官网 : https://www.elastic.co/guide/en/elasticsearch/reference/2.4/mapping-field-names-field.html#mapping-field-names-field