Observability

Seeing inside a running system: metrics and time-series storage, range queries and downsampling, alerting, and the cardinality that decides whether it all fits in memory.

Explainers

• Design a Metrics & Monitoring System — From a metrics table in Postgres to a purpose-built time-series database — the append-only TSDB, delta-of-delta plus XOR compression, the cardinality bomb that decides whether it fits in RAM, downsampling, and an alerting pipeline that watches itself.