我正在阅读如何使用运行时字段并遵循以下说明：https://www.elastic.co/guide/en/elasticsearch/reference/current/runtime-search-request.html
下面给出的例子是，它创建了一个名称为day_of_week的运行时字段。我的问题是，我如何在source字段内为运行时字段做另一个查询。换句话说，day_of_week的值保存在另一个索引中。是否可以做到这一点？

GET my-index-000001/_search
{
  "runtime_mappings": {
    "day_of_week": {
      "type": "keyword",
      "script": {
        "source": "emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))"
      }
    }
  },
  "aggs": {
    "day_of_week": {
      "terms": {
        "field": "day_of_week"
      }
    }
  }
}