Problem Statement
Design a key-value store that supports transactional operations. This store should be capable of operating both in-memory and with disk-backed persistence.
Functional Requirements
- Basic Operations:
Get(key): Retrieve the value associated with a given key.Put(key, value): Store or update a value for a given key.Delete(key): Remove a key-value pair.
- Transactions:
Begin(): Start a new transaction.Commit(): Atomically apply all changes made within the current transaction.Rollback(): Discard all changes made within the current transaction.
- Concurrency: Support multiple concurrent clients interacting with the store.
Transaction Semantics
The store must provide, at a minimum, atomicity and isolation for transactions. The specific isolation level (e.g., Read Committed, Snapshot Isolation) should be defined and discussed during the interview.
Non-Functional Requirements
- Performance: Achieve reasonable performance under concurrent access patterns.
- Durability (Optional): If required, the system should ensure data survives crashes. The necessity for durability will be clarified during the interview.
- Scalability: Support datasets that may exceed available memory, implying disk-backing.
Deliverables
Candidates are expected to present and discuss:
- The proposed APIs for the key-value store and its transactional interface.
- The data model and underlying storage layout.
- The chosen approach for concurrency control.
- A strategy for crash recovery, if durability is a requirement.
- An analysis of the system's complexity and key architectural trade-offs.
AI interview prep
Core dilemma
Balancing strong transactional guarantees (ACID properties, especially isolation and atomicity) with high concurrency and performance, particularly when dealing with disk-backed storage and potential crash recovery.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Problem Statement
Design a key-value store that supports transactional operations. This store should be capable of operating both in-memory and with disk-backed persistence.
Functional Requirements
- Basic Operations:
Get(key): Retrieve the value associated with a given key.Put(key, value): Store or update a value for a given key.Delete(key): Remove a key-value pair.
- Transactions:
Begin(): Start a new transaction.Commit(): Atomically apply all changes made within the current transaction.Rollback(): Discard all changes made within the current transaction.
- Concurrency: Support multiple concurrent clients interacting with the store.
Transaction Semantics
The store must provide, at a minimum, atomicity and isolation for transactions. The specific isolation level (e.g., Read Committed, Snapshot Isolation) should be defined and discussed during the interview.
Non-Functional Requirements
- Performance: Achieve reasonable performance under concurrent access patterns.
- Durability (Optional): If required, the system should ensure data survives crashes. The necessity for durability will be clarified during the interview.
- Scalability: Support datasets that may exceed available memory, implying disk-backing.
Deliverables
Candidates are expected to present and discuss:
- The proposed APIs for the key-value store and its transactional interface.
- The data model and underlying storage layout.
- The chosen approach for concurrency control.
- A strategy for crash recovery, if durability is a requirement.
- An analysis of the system's complexity and key architectural trade-offs.