Well, I want to build a large-scale project, but I do not know which ORDBMS to choose. The app should handle real-time operations, not chatting, but things like future scheduling or reminders. It should be also really secure, fast and easy to use. And last but not least, should I use them both. I mean PostgreSQL with Python / Django and MongoDB with Node.js? Or would it be better to use PostgreSQL with Node.js?
*The project is going to use React for the front-end and GraphQL is going to be used for the API.
Thank you all. Any answer or advice would be really helpful!
Unless you have need for consensus writes or cross-region replication, I generally prefer Postgres over Mongo.
You can use Postgres with either language and it can be performant if you use an RDBMS or are thoughtful about your query construction.
Given your need for security, I'd definitely interact with the database through a mature RDBMS and use well-vetted frameworks and consider going through a rigorous security evaluation every so often.
I personally think that Postgres is easier to reason about than Mongo because of its relational nature and comfort with constraints. Maintaining any sort of relational features in Mongo tends to require a lot of application code for features Postgres offers out of the box.