What is the CQRS (Command Query Responsibility Segregation) pattern, and how does it fit into microservices?

Short answer: CQRS is a pattern that separates the read (query) operations from the write (command) operations to optimize performance, scalability, and security in systems.

Explain a bit more

In microservices: Command Side: The microservices handling writes (e.g., creating or updating data) are responsible for applying business logic and persisting data. Query Side: The microservices handling reads have an optimized, often denormalized, view of the data to provide faster responses. Why it's useful: Improves scalability by allowing reads and writes to scale independently. Enables optimized storage for read-heavy operations, like using a NoSQL database for reads and a relational DB for writes.

Example code

In an E-commerce system, you might separate the Order Command Service (handling order creation) from the Order Query Service (serving read-optimized views of order data).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.