Which database to use for storing machine learning data?
I share here the results of my quick research:
I think I will create a mongodb database to store everything, because it is easy to use and accross the NoSQL databases it is the one my company knows best.
If you want to use a database, you may also consider things like parallel access, distributiveness of the database, resilience, etc.
I think more advanced solutions like shared filesystems, spark, hadoop, sciDB (in particular, sciDB seems specialized for analytics on arrays only) etc are good for data lakes and when we want to process ALL the data or a big part of it at the same time, per batch or through a pipeline for example. Therefore, I don't need it for now, and the simpler the best.