AI & Technical question
How would you decrease the amount of storage needed for storing e-mail messages for Gmail?
- AI & Technical
- Hard
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What this question tests
AI and technical product thinking: can you propose concrete storage-reduction mechanisms and reason about their tradeoffs for a mail product at massive scale.
How to approach it
- Identify the biggest storage drivers: attachments (images, documents) typically dwarf plain text in storage footprint.
- Propose deduplication: many users receive identical attachments (e.g. newsletters, shared files) that could be stored once and referenced, not duplicated per mailbox.
- Propose compression and format optimization: more aggressive compression for older, rarely-accessed attachments and images, with a tradeoff of slightly slower retrieval.
- Propose tiered storage: move old, rarely-accessed emails to cheaper, slower cold storage automatically, reserving fast storage for recent/active mail.
- Consider a policy lever: default auto-archiving or prompting users to delete old large attachments they no longer need, with user consent and control.
- Define success: total storage cost per user reduced, while keeping retrieval latency for recently accessed mail unaffected.
What a strong answer includes
- Proposes deduplication of shared attachments as a concrete, high-leverage mechanism specific to a mail system at scale.
- Distinguishes hot (frequently accessed) from cold (rarely accessed) data and proposes tiered storage accordingly, a standard, realistic infra pattern.
- Weighs the tradeoff of compression (storage savings versus retrieval speed) explicitly rather than presenting it as a free win.
- Keeps a user-consent lens on auto-archiving/deletion policies, since deleting user data without care is a real risk.
Common mistakes
- Proposing only 'compress everything' without considering the retrieval-speed tradeoff or which data benefits most.
- Ignoring deduplication of shared attachments, one of the highest-leverage techniques for a mail system specifically.
Likely follow-up questions
- How would you handle a user who wants instant access to all their old attachments despite cold storage tiering?
- How would you measure the actual storage savings from deduplication given attachments vary widely?
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Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 1: Foundations: the model and the decisions it forces on you
- Chapter 8: Evals: define good and make the number defensible
- Chapter 6: Agents and agentic architecture