hardDesignScenarioSeniorStaffLead
Your data is pinned per region, but login must be globally unique and admins want one global search. How do you build that?
6 min readUpdated 2026-08-15
Answer
Short answer
Keep one small global directory holding only the keys needed to route a request, never the payload. Uniqueness becomes a claim on a pseudonymous token, search becomes a fan-out that returns pointers each region resolves locally, and every field promoted to the global tier is a transfer decision.
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Likely follow-ups
- A region is offline. Should signup be blocked globally, or do you allow a uniqueness check to be eventually consistent?
- How do you migrate a user from one home region to another once records exist in both?
- What does the audit trail for a cross-region admin search look like, and where does it live?
- Support needs to see a customer's data from another region during an incident. What do you allow?
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