目前我正在学习，仍然是Elasticsearch的新手。
我尝试创建一个包含多个排序字段（id，created_at）的索引。我的计划是尝试在Python Elasticsearch Client的search函数中使用search_after参数。
下面是我已经尝试过的查询：

PUT /my-index
{
  "settings": {
    "index":[
      {
        "sort.field": "created_at", 
        "sort.order": "asc"
      },
      {
        "sort.field": "id", 
        "sort.order": "asc"
      }
    ]
  },
  "mappings": {
    "properties": {
      "id": {
        "type": "keyword",
        "doc_values": true
      },
      "name": {
        "type": "keyword"
      },
      "created_at": {
        "type": "date"
      }
    }
  }
}

但是，我得到了这样的错误：

{
  "error" : {
    "root_cause" : [
      {
        "type" : "settings_exception",
        "reason" : "Failed to load settings from [{\"index\":[{\"sort.field\":\"created_at\",\"sort.order\":\"asc\"},{\"sort.field\":\"id\",\"sort.order\":\"asc\"}]}]"
      }
    ],
    "type" : "settings_exception",
    "reason" : "Failed to load settings from [{\"index\":[{\"sort.field\":\"created_at\",\"sort.order\":\"asc\"},{\"sort.field\":\"id\",\"sort.order\":\"asc\"}]}]",
    "caused_by" : {
      "type" : "illegal_state_exception",
      "reason" : "only value lists are allowed in serialized settings"
    }
  },
  "status" : 500
}

请帮助我。提前感谢！