title: Reading a TFRecord file where features that were used to encode is not known
body: <p>I am very new to TensorFlow and this might be a very beginner question. I have seen examples where custom datasets are converted to TFRecord files using the knowledge of the features one wants to use (for example-'image', 'label'). And while parsing this TFRecord file back, one has to know the features beforehand (i.e. 'image', 'label') in order to be able to use this dataset.</p>
  <p>My question is- how do we parse TFRecord files where we do not know the features beforehand? Suppose someone gives me a TFRecord file and I want to decode all the associated features with this.</p>
  <p>Some examples which I am referring to are: <a href="https://stackoverflow.com/questions/37151895/tensorflow-read-all-examples-from-a-tfrecords-at-once/39376833">Link 1</a>, <a href="https://stackoverflow.com/questions/55378569/i-want-to-read-data-from-tfrecord">Link 2</a></p>