JSONPATHSTRING

{
  "data": {
    "name": {"full.name": "Peter", "nick.name": "Pete"},
    "age": 24,
    "subjects": [
      {
        "name": "maths",
        "homework_grades": [80, 85, 90, 95, 100],
        "grade": "A",
        "score": 90
      },
      {
        "name": "english",
        "homework_grades": [60, 65, 70, 85, 90],
        "grade": "B",
        "score": 70
      }
    ]
  }
}

{
   "tableConfig":{
      "ingestionConfig":{
         "transformConfigs":[
            {
               "columnName":"age",
               "transformFunction":"JSONPATHSTRING(data, '$.age')"
            },
            {
               "columnName":"nickName",
               "transformFunction":"JSONPATHSTRING(data, '$.name[\"nick.name\"]')"
            }
         ]
      }
   }
}