Synchronize table metadata with features
MEMBER
See PR #2274 
2021-04-28T12:48:25Z
https://github.com/huggingface/datasets/issues/2271#issuecomment-828427330
https://api.github.com/repos/huggingface/datasets/issues/2271
MDEyOklzc3VlQ29tbWVudDgyODQyNzMzMA==
https://api.github.com/repos/huggingface/datasets/issues/comments/828427330/reactions
2021-04-28T12:48:25Z
https://api.github.com/repos/huggingface/datasets/issues/comments/828427330
https://avatars.githubusercontent.com/u/42851186?v=4
https://api.github.com/users/lhoestq/events{/privacy}
https://api.github.com/users/lhoestq/followers
https://api.github.com/users/lhoestq/following{/other_user}
https://api.github.com/users/lhoestq/gists{/gist_id}
https://github.com/lhoestq
lhoestq
MDQ6VXNlcjQyODUxMTg2
https://api.github.com/users/lhoestq/orgs
https://api.github.com/users/lhoestq/received_events
https://api.github.com/users/lhoestq/repos
https://api.github.com/users/lhoestq/starred{/owner}{/repo}
https://api.github.com/users/lhoestq/subscriptions
User
https://api.github.com/users/lhoestq
public
**Is your feature request related to a problem? Please describe.**

As pointed out in this [comment](https://github.com/huggingface/datasets/pull/2145#discussion_r621326767):
> Metadata stored in the schema is just a redundant information regarding the feature types.
It is used when calling Dataset.from_file to know which feature types to use.
These metadata are stored in the schema of the pyarrow table by using `update_metadata_with_features`.
However this something that's almost never tested properly.

**Describe the solution you'd like**

We should find a way to always make sure that the metadata (in `self.data.schema.metadata`) are synced with the actual feature types (in `self.info.features`).