Common Design Mistakes
Common Design Mistakes
Building a large-scale system is hard. Here are some of the most common mistakes that even experienced developers make.
1. Over-Engineering
Adding complex features before they are needed.
- Example: Building a system for 10 million users when you only have 100.
- Problem: It takes too long to build and is expensive to maintain.
2. Ignoring “Single Point of Failure” (SPOF)
Having a component that, if it fails, crashes the whole system.
- Example: Having only one database with no backup.
- Problem: If the database server crashes, your whole app goes down.
[ Server 1 ] [ Server 2 ] [ Server 3 ]
\ | /
\ | /
v v v
[ One Database ] <--- SPOF!
3. Not Monitoring Performance
Building a system and then never checking how it’s actually doing.
- Example: Not knowing when your servers are running out of RAM.
- Problem: You only find out about issues when your users start complaining.
4. Hard-Coding Configurations
Putting server addresses or API keys directly into your code.
- Example:
const db_url = "http://192.168.1.100"; - Problem: If you change your server’s address, you have to rewrite and redeploy your code.
5. Forgetting About Latency
Designing a system that works locally but is slow when users are far away.
- Example: Having a single database in New York while your users are in Japan.
- Problem: Data takes too long to travel over the ocean, making the app feel “laggy.”
How to Avoid These Mistakes:
- Start Simple: Build what you need now, but design it so it’s easy to scale later.
- Think About Failures: Always ask yourself, “What happens if this component crashes?”
- Test with Real Data: Don’t just test with 10 users; see what happens with 1,000.