# Observability
All Observability notes →1 — Prometheus
Covers Prometheus as the reference pull-based metrics engine — see the dedicated Prometheus book for full depth; this chapter covers only its role in the broader platform.
3 — Loki
Covers Loki's index-light, label-indexed log storage model and how it differs from full-text log indexing.
4 — Tempo
Covers Tempo’s object-storage-backed, trace-ID-lookup model for cost-efficient distributed trace storage.
5 — Pyroscope
Covers Pyroscope as a continuous-profiling backend and its data model for flame-graph-over-time queries.
6 — Elasticsearch
Covers Elasticsearch as a full-text-indexed log and event store, and its cost/flexibility tradeoff against label-indexed alternatives.
7 — Clickhouse
Covers ClickHouse as a columnar OLAP engine increasingly used as a unified backend for logs, traces, and wide events.
8 — Opensearch
Covers OpenSearch as the open-source Elasticsearch fork and its divergence points relevant to an observability backend choice.