elasticsearch - "null_value"不允许用于 "text"字段？

Question

我正在尝试为“文本”字段定义“null_value”(版本 5.1.1)。像这样:

PUT students
{
  "mappings": {
    "student": {
      "properties": {
        "first_name": {
          "type": "text",
          "null_value": "No First Name"
        }
      }
    }
  }
}

这会导致错误:

{
  "error": {
    "root_cause": [
      {
        "type": "mapper_parsing_exception",
        "reason": "Mapping definition for [first_name] has unsupported parameters:  [null_value : No First Name]"
      }
    ],
    "type": "mapper_parsing_exception",
    "reason": "Failed to parse mapping [student]: Mapping definition for [first_name] has unsupported parameters:  [null_value : No First Name]",
    "caused_by": {
      "type": "mapper_parsing_exception",
      "reason": "Mapping definition for [first_name] has unsupported parameters:  [null_value : No First Name]"
    }
  },
  "status": 400
}

但是如果 "first_name"被标记为 "type": "keyword"，它就会成功。看着 documentation ，它没有说明“null_value”仅适用于“关键字”类型的字段。我在这里遗漏了什么吗？

Answer 1

null_value 不允许出现在 text 数据类型中。查看表格以了解 text 数据类型的允许参数。 https://www.elastic.co/guide/en/elasticsearch/reference/5.1/text.html#text-params