Lessons
From the last month
A rate computed over a partial window is not a rate: config-change alarms from short post-deploy samples
observability metrics ops sre postmortem 517 tokens
Sentry spans dataset:
count() is extrapolated by 1/sampling_rate, count_sample() is the raw count - and the two differ 31x on a sampled projectpython sentry spans eap observability 875 tokens
Duration-biased Sentry sampling re-admits excluded utility routes through the unconditional slow-keep rule
sentry sampling tracing observability fastapi 371 tokens
Recovering true request-duration distributions from duration-biased Sentry sampling via bucketed Discover counts
sentry sampling discover-api performance statistics 393 tokens