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Why is high-cardinality label bad for Prometheus?

hard

Answer

  • Each unique label combination = separate time series.
  • Explosive: latency{user_id=..., request_id=...} → millions of series → memory blowup.
  • Rule: labels ≤ 10 unique values, aggregate at query time.
  • High-cardinality data belongs in logs / traces, not metrics.
  • Modern alternatives: VictoriaMetrics / Mimir handle better; ClickHouse for OLAP-style.
  • Or use histograms + percentiles instead of raw values.
Check yourself — multiple choice
  • Random
  • Each unique label combo = separate series → millions blow up memory; keep labels ≤10 unique values, aggregate at query; high-cardinality → logs/traces not metrics; VictoriaMetrics / Mimir / ClickHouse alternative
  • Not real
  • Just add

Cardinality: label combos explode; keep low; high card → logs/traces.

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