Google·Software Engineer·Onsite - System Design / Architecture
May 2026
System design round at Google focused entirely on distributed transactions, which sounds manageable until you realize they want you to compare three different coordination patterns and reason through failure modes in real time. Tough session, lots of follow-ups.
- Design a distributed transactions protocol that coordinates updates across multiple services or databases. Walk through two-phase commit, three-phase commit, and the Saga pattern, including message flows, failure handling, idempotency, timeouts, and exactly-once vs at-least-once delivery guarantees.
“Started with 2PC because it felt safe, but the interviewer kept pushing on the coordinator failure scenario and I fumbled it.” The rest of the author's notes on Software Engineer interview at Google, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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