至于在摄取级别删除空字段--设置一个管道：

PUT _ingest/pipeline/no_empty_fields
{
  "description": "Removes empty-ish fields from a doc",
  "processors": [
    {
      "script": {
        "source": """
          def keys_to_remove = ctx.keySet()
                          .stream()
                          .filter(field -> ctx[field] == null || 
                                           ctx[field] == "")
                          .collect(Collectors.toList());

          for (key in keys_to_remove) {
            ctx.remove(key);
          }
        """
      }
    }
  ]
}

并在索引时应用它

POST myindex/_doc?pipeline=no_empty_fields
{
  "fieldname23": 123,
  "fieldname": null,
  "fieldname123": ""
}

当然，可以将条件扩展到其他字段，例如 "undefined" , "Infinity" 和其他人。