Ace the Rust Interview

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advanced · order 172

Single-node KV + WAL sketch

design-kv-01Related book chapters: 26, 27 (optional — this page is complete on its own)system-design

Slug: design-kv-01 · Paired reading: Chapters 26 and 27

Prompt

struct Kv { wal: Vec<(String,String)>, map: HashMap<String,String> } — set appends WAL then map; get from map; fn recover(wal) -> Kv.

Contract

  • set appends one WAL record then updates the map (last write wins for get)
  • recover(wal) rebuilds the map from wal without re-appending WAL entries (restored.wal == wal)
  • Missing keys → None