I’ve always enjoyed conducting technical interviews, especially when it comes to challenging candidates with questions that require them to think critically about core engineering concepts. One of my favorite ways to kick off these conversations is by diving into problems that mirror real-world scenarios we face in backend development — problems that involve databases, message queues, and distributed systems. My goal isn’t just to quiz candidates, but to engage them in a discussion, just like we would in the day-to-day work of an engineering team.
Here’s a scenario I often present to candidates:
Imagine we’re working within a large, distributed system. We frequently exchange messages, both asynchronously and synchronously, and sometimes we need to write data to a database while simultaneously publishing a message to a queue. How would you design a mechanism to ensure that both the write and the publish happen reliably?
The conversation usually steers towards the dual-write problem, a common issue when dealing with multiple external systems. It’s important for candidates to grasp that simply writing to the database and then publishing to the queue isn’t enough. What happens if…