System designHardsd-g675

Subject Graph database shardingLevel Senior–Staff~45 minCommon in Databases & SQL · Distributed systems · Algorithms & data structures interviewsIndustries Technology, Software development

Question

Design the storage and sharding for a social graph database backing a 'people you may know' / friends-of-friends feature, with 1 billion users averaging 300 connections (some celebrities have 50M), serving 80k graph traversals/sec that walk 2–3 hops. How do you store the adjacency data, shard the graph, and keep 2-hop traversals fast despite supernodes that span many shards?

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

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Run or narrate your approach, then ask the coach.