System design interview question
"Design an in-memory database — something like Redis. It holds data in RAM for microsecond access, supports rich data structures beyond plain key-value, and must not lose data when the process restarts. Hundreds of gigabytes, millions of operations per second."
the durability paradox — an in-memory store's whole value is avoiding disk, yet it must survive restarts, so you have to touch disk in a way that does not undo the benefit. Secondary content: why single-threaded execution is often the right choice, memory management, and what happens when RAM fills.
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