Design an Analytics Dashboard

Design a product-analytics service for customers of a SaaS product. Customers send raw events, define metrics, and view dashboards of those metrics over time with filters and group-bys, backed by raw events. Each customer is a tenant who must never see another's data.

In scope: event ingestion, storage layout, rollups, the query path and caching, late events, and tenant isolation. Out of scope: the visualization front end and ML-driven insights.