I am learning to design systems, specifically the database part in it and I know a lot of similar posts are available on SO but either they are a decade old (and a lot has changed since then) or they don't have helpful answers.
All the previous answers or blog posts compare relational and non-relational DBMS (or SQL and NoSQL) in some way. And I can't see a well defined line between the two. Because as soon as I read about a property of NoSQL DBMS, I find there's a latest version of a SQL DBMS that provides the same property and vice versa. For example, Document data-stores store data in JSON-like objects and you can even query into these objects but then I found that PostreSQL also provides this functionality.
Next common point of comparison is Scalability. Well, I can see a lot of giants like Amazon using SQL dbms and they don't seem to have any scalability issues.
Next point of comparison is that SQL dbms enforce schema. We can kind of do that with MongoDB schema validation.
And now newSQL databases claim to provide the scalability of NoSQL systems for online transaction processing (OLTP) workloads while maintaining the ACID guarantees of a traditional database system.
So it seems like Relational dbms and Non-relational dbms are moving towards each other.
Keeping all these things in mind, how to choose a dbms? I mean what points do you consider? What's the thought process?
Thank you!