What is the best practice for data folder structuring?
What are the best practices you apply? What would you recommend?


My practice is "kind of structured but quite different every time", and I don't recommend it ;) 

I suspect that I'm not the only one but I don't have any stats.

Thanks for the link to Cookiecutter, this looks interesting! After reading a bit about it, it looks to me like a key criterion is this: "anyone should be able to reproduce the final products with only the code in src and the data in data/raw."

Based on that I would argue that:


  
  You have acces to SQL databases and make a no-modification extract -> Still into Raw I guess?
  


Yep, because this data cannot be obtained by processing some other part of the raw data.


  
  Because of very large databases, you create a semi-complex SQL query as base for a feature -> Is this Raw or Interim?
  


Assuming this query is run on the raw sql database, the resulting data goes to interim, because it can be re-generated by running the query again.
The query itself should be stored in src/features I think.