← Instacart Interview Insights
Seemed simple at first and I jumped straight to schema design without asking about scale or access patterns.
Start by clarifying requirements: what queries and updates are expected, scale, and consistency needs. Then propose a data model with a unique ID as the primary key, and discuss storage options (e.g., relational database, key-value store) with trade-offs. Finally, outline the API for adding a worker and the operations for querying and updating, considering indexing and concurrency.
Pro tip: Demonstrate awareness of real-world constraints by discussing how you would handle schema evolution and data migrations, especially since Instacart operates at scale with evolving requirements.
Ask about expected query patterns (e.g., by ID, by title, by salary range), update frequency, data volume, and consistency requirements. This shapes the design.
Define the worker entity with fields: unique ID (primary key), title, salary. Consider if additional metadata like timestamps or versioning is needed.
Select a database (e.g., relational for complex queries, NoSQL for scale) and define indexes on fields likely to be queried (e.g., title, salary). Discuss trade-offs.
Specify the addWorker method, along with query and update operations. Include input validation, error handling, and idempotency for updates.
Discuss how the design handles growth: sharding, replication, caching, and concurrency control (e.g., optimistic locking for updates).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.