Hello Interview @_hellointerview

Prepare for your upcoming SWE interviews! hellointerview.com/twitter Joined May 2023

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Hello Interview @_hellointerview

a day ago

Full breakdown of cache invalidation and read scaling patterns: hellointerview.com/learn/system-d…

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Hello Interview @_hellointerview

a day ago

Knowing the names isn't the signal. Naming which failure mode you're willing to accept, and why, is what separates a candidate who's memorized patterns from one who's thought through the system.

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Hello Interview @_hellointerview

a day ago

Every cache eventually lies. The moment data lands in memory, it starts drifting from the source of truth. The question isn't whether to invalidate, it's which failure mode you're willing to accept.

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Hello Interview @_hellointerview

3 days ago

Cache invalidation is famously hard, and you've added a new failure surface. The speed gain is real, but so is the operational cost. That tradeoff is what makes caching a deliberate choice, not a default.

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Hello Interview @_hellointerview

3 days ago

A cache like Redis sits between your app and your database, serving repeated reads from memory with no disk access. That's the difference between ~1ms and ~50ms per read. The tradeoff is you're now responsible for keeping that data consistent.

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Hello Interview @_hellointerview

3 days ago

Read replicas and Redis both reduce load on your primary database. They're not interchangeable. They operate at different layers, and picking the wrong one for your bottleneck is a common system design mistake.

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Hello Interview @_hellointerview

5 days ago

Pattern recognition over pattern matching. Practice it at hellointerview.com/learn/code/gre…

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Hello Interview @_hellointerview

5 days ago

The signal interviewers want: can you recognize when greedy is valid, not just reach for DP because the problem mentions "minimum"?

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Hello Interview @_hellointerview

5 days ago

Jump Game II looks like a DP problem. Choices at every step, a minimum to optimize, overlapping subproblems. It's greedy, and the reason why is worth understanding.