← Applied intuition Interview Insights
I started with the basic get/set/delete part, which felt fine, then they said 'now add transactions' and I kind of froze for a second.
Start by clarifying requirements and constraints, then propose a design using a stack of transaction layers, each with its own key-value map and a reference to its parent. Explain how operations like get, set, and delete traverse the stack, and how commit and rollback manipulate the stack. Finally, discuss trade-offs and potential optimizations.
Pro tip: Emphasize that nested transactions require a stack of layers, and that commit merges changes into the parent while rollback discards the top layer. Mention that this design ensures isolation and atomicity within transactions.
Ask about expected operations, concurrency, persistence, and performance constraints to scope the design appropriately.
Propose a stack of transaction layers, each containing a map for key-value pairs and a reference to its parent layer.
Explain how get, set, and delete work by searching from the top layer down to the base, and how begin, commit, and rollback manipulate the stack.
Address time/space complexity, potential optimizations like copy-on-write or lazy propagation, and handling of edge cases.
Sketch code for the core operations and outline test cases for nested transactions, rollbacks, and commits.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.