That all depends on the database you use it with.
When it comes to sharding it means multiple processes accessing the database. Something like a json file is extremely dangerous to do. Sqlite3 is a bit less but you need to know that only one process can write at a time. Other bigger database servers like mysql there should be no problem at all as they are made for having multiple connections. I will always recommend a database server over anything even Sqlite3 because it can in fact corrupt more easily