title: Dataset Viewer issue for strombergnlp/ipm_nel : preview is empty, no error message
comments: Hi @leondz, thanks for reporting.
  
  Indeed, the dataset viewer relies on the dataset being streamable (passing `streaming=True` to `load_dataset`). Whereas most of the datastes are streamable out of the box (thanks to our implementation of streaming), there are still some exceptions.
  
  In particular, in your case, that is due to the data file being TAR. This format is not streamable out of the box (it does not allow random access to the archived files), but we use a trick to allow streaming: using `dl_manager.iter_archive`.
  
  Let me know if you need some help: I could push a commit to your repo with the fix. Ah, right! The preview is working now, but this explanation is good to know, thank you. I'll prefer formats with random file access supported in datasets.utils.extract in future, and try out this fix for the tarfiles :)
body: ### Link
  
  https://huggingface.co/datasets/strombergnlp/ipm_nel/viewer/ipm_nel/train
  
  ### Description
  
  The viewer is blank. I tried my best to emulate a dataset with a working viewer, but this one just doesn't seem to want to come up. What did I miss?
  
  ### Owner
  
  Yes