High Cardinality Metrics: How Prometheus and ClickHouse Handle Scale
TL;DR: Prometheus pays cardinality costs at write time (memory, index). ClickHouse pays at query time (aggregation memory). Neither is "better":they fail differently. Design your pipeline knowing which failure mode you're accepting. -- Every month, someone posts "just use ClickHouse for metrics" or "Prometheus can't handle scale." Both statements contain a kernel of truth wrapped in dangerous oversimplification.