System design interview tip: Don’t optimize prematurely

In our 4-step system design interview framework, the second step is “Propose High-level Design and Get Buy-in”. The objective of this step is to come up with a high-level design diagram for the problem at hand and establish a common ground for further exploration.

It is a red flag to get carried away this early in the session with premature optimizations. For example, some candidates love to talk about caching and sharding in this step.

Optimizations are complicated and expensive. They require solid justifications for the added complexity. At this early stage, the justifications are often hand-wavy. The added complexity distracts the interviewer and prevents them from understanding the high-level design.

Focus on the task at hand. If you find yourself getting distracted by optimization ideas, table them. Make a list of ideas to revisit in the deep dive section.

Keep the high-level design simple. This step should take about 15 minutes.

What are some other premature optimizations that can be tabled?

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If you enjoyed this post, you might like our system design interview books as well.

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