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Heygen·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Interviewed for a software engineer role at Heygen. Not much to go on from what I remember but there was at least one system design flavored question that stuck with me.

Questions Asked (1)

Q1

How would you store or persist the machines you've acquired over time?

System DesignData ModelingTechnical Trade-offs
Author's notes

This one made me pause.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the domain: 'machines' likely refers to compute instances or nodes (e.g., GPU machines) acquired for AI video processing. Then propose a data model that captures machine metadata, state, and lifecycle, and discuss storage options (relational DB, key-value store, or time-series DB) with trade-offs around consistency, scalability, and query patterns.

Pro tip: Emphasize that the choice of storage depends on access patterns and scale—e.g., if you need fast lookups by machine ID, a key-value store like Redis or DynamoDB works well; if you need complex queries and relationships, a relational DB like PostgreSQL is better. Also mention the importance of tracking machine state changes over time for auditing and debugging.

1. Clarify requirements and assumptions

Ask questions to understand what 'machines' are (e.g., physical servers, VMs, containers), the scale (thousands to millions), and access patterns (read-heavy, write-heavy, queries by attributes).

2. Define the data model

Outline key entities and attributes: machine ID, type, specs (CPU, GPU, memory), acquisition date, status (active, idle, decommissioned), owner, location, and cost. Consider relationships to other entities like users or jobs.

3. Choose storage technology

Evaluate options: relational (PostgreSQL) for strong consistency and complex queries; NoSQL (MongoDB, DynamoDB) for scalability and flexible schema; time-series (InfluxDB) for metrics; or a hybrid approach. Discuss trade-offs.

4. Design for lifecycle and state changes

Explain how to handle updates (e.g., status changes) and historical tracking. Consider event sourcing or audit tables to log changes over time for debugging and compliance.

5. Address scalability and performance

Discuss partitioning/sharding, indexing strategies, caching, and read replicas to handle growth. Mention backup and recovery plans.

Key Points to Mention

  • Data model: machine attributes, status, and relationships
  • Storage options: relational vs. NoSQL vs. time-series with trade-offs
  • Indexing and query patterns for efficient retrieval
  • Handling state transitions and historical data (audit logs, event sourcing)
  • Scalability considerations: sharding, replication, caching
  • Consistency and availability trade-offs (CAP theorem)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.