System designMediumsd-g207

Subject Geo replicationLevel Mid–Senior~40 minCommon in Databases & SQL · Distributed systems interviewsIndustries Technology, Software development

Question

Design read-scaling for a multi-tenant SaaS app (project management) where the primary DB is in us-east but 40% of users are in Europe and complain about slow page loads. You want to serve European reads locally from replicas while keeping correctness: a user who just saved a task must see it on the next page load, and dashboards can tolerate a few seconds of staleness. How do you architect the replica topology and routing?

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

Loading whiteboard…

Run or narrate your approach, then ask the coach.