All things aside, the main problem I had with MongoDB when I've tried to use it in one of my projects (in NodeJS) was the way to query data. I know, there are s

All things aside, the main problem I had with MongoDB when I've tried to use it in one of my projects (in NodeJS) was the way to query data. I know, there are some libraries for that, but it's just pain in the ass to make complex queries - something which would be an easy JOIN in SQL, in MongoDB is a big pile of callbacks and long, chained method calls. It was just hard to maintain, and the data structure flexbility didn't make it easier which led to a completely messed up database.