How do you decide sampling rates for traces? [Advanced]
Answer
I choose trace sampling rates based on traffic volume, incident value, latency/error risk, compliance needs, and backend cost. I keep all or most errors and rare critical paths, while sampling high-volume successful traffic more aggressively.
Technical explanation
Uniform sampling is simple but can miss rare failures in high-volume systems.
Rules-based sampling can retain errors, slow requests, VIP tenants, or critical endpoints.
Sampling decisions should be reviewed with actual trace volume and incident usefulness, not guessed once and forgotten.
Hands-on example
Example policy: keep 100 percent of traces with error=true, 100 percent of checkout payment flows, 10 percent of normal checkout success traces, and 1 percent of high-volume read-only catalog requests. Revisit rates monthly based on backend cost and debugging gaps.
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