DSA TrainerSystem Design · Unit 5
SQL vs NoSQL
"Which database?" is one of the first real decisions in a design, and it is where beginners most often reach for a buzzword instead of a reason. The honest answer is almost never "NoSQL because it scales" or "SQL because it is safe." It is "here is the shape of my data and how I read and write it, and that points to this kind of database."
At a high level there are two families. Relational databases (SQL) store data in tables of rows with a fixed schema and strong support for relationships and transactions. NoSQL is an umbrella for everything else: flexible-schema stores optimized for scale or for specific access patterns.
This unit is about making the call on purpose. You will learn what each family is genuinely good at, and how to answer the interviewer who insists one is always right.
The rest of the System Design course is premium
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