Reference · Glossary
Metric cardinality
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Cardinality is how many unique time series a metric creates; high-cardinality labels (user IDs) can explode cost and break Prometheus.
#When to use
Production AI and API services where you need visibility, safer deploys, or verified inbound callbacks.
#When not to
Local one-off notebooks with no users. Do not collect high-cardinality labels “just in case.”
#Practical tips
- Prefer a few well-named metrics over dozens of vanity charts
- Alert on symptoms users feel (errors, latency) before chasing every gauge
- Keep runbooks next to dashboards
#Learn next
- Lesson: `ai-monitoring`
- Related: prometheus, observability