My first instinct was to just keep everything in a hashmap and call it a day.
Start by clarifying requirements (data size, read/write ratio, durability, performance) and then propose a simple design using an append-only log with an in-memory index, discussing trade-offs. Implement core operations and recovery, and consider optimizations like compaction and indexing.
Pro tip: Demonstrate awareness of real-world systems (e.g., Bitcask, LSM trees) and discuss how your design would scale or handle failures, showing you think beyond basic functionality.
Ask about expected data volume, read/write patterns, durability guarantees, and performance targets to guide design decisions.
Propose an architecture: append-only log for persistence, in-memory hash index for fast lookups, and periodic compaction to reclaim space.
Detail how put, get, and delete work: put appends a record and updates index; get reads from index and retrieves value; delete appends a tombstone and removes from index.
Explain how to rebuild the in-memory index by replaying the log from disk on startup, ignoring tombstones and older values.
Discuss trade-offs (e.g., memory usage vs. speed) and potential optimizations like sparse indexes, SSTables, or LSM trees for larger scale.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.