System design interview question
Design a Distributed Event Sourcing and CQRS System for Real-Time Analytics like Mixpanel at Scale
Design a system that ingests, processes, and serves analytics events for 500M users generating 2M events per second with sub-second query latency. The system must support complex event filtering, funnel analysis, cohort segmentation, and real-time dashboards while maintaining strong consistency for critical business metrics. Events arrive from mobile, web, and backend sources across 3 geographic regions. You must handle backpressure, deduplication, late arrivals (up to 24 hours), and provide both real-time (< 1s) and historical analytics queries (7-year retention). Consider how you'd separate writes (event ingestion) from reads (analytics queries), ensure exactly-once processing semantics, and maintain low operational complexity.
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