hardDesignMidSeniorStaff
Design the ingestion path for sensor telemetry from a few hundred machines. Which decisions matter most?
6 min readUpdated 2026-08-15
Answer
Short answer
Size the stream from stated assumptions, keep series identity narrow so cardinality stays bounded, choose sampling deliberately and downsample keeping min, max and count rather than means alone, tier retention, and buffer at the edge with a bounded queue and a rate-limited drain.
Was this answer helpful?
Likely follow-ups
- Where would you store the batch number and operator for a reading, if not as labels on the series?
- The edge buffer holds six hours and the link has been down for two days. What do you do?
- How would you detect that a tag has silently stopped reporting?
- Two machines' clocks differ by nine seconds. What breaks, and how do you find out?
Related questions
- Five months after a machine failure, an engineer asks you for the high-rate data around it. Was your retention policy right?hardAlso on retention and downsampling7 min
- How do you handle personal data in prompts, logs and traces for an LLM feature?mediumAlso on retention5 min
- One machine's clock is ninety seconds ahead of the rest of the plant. Which of your numbers are wrong, and how would you have found out?hardAlso on time-series7 min
- How do you design a system so an auditor can prove who accessed a record and why?mediumAlso on retention8 min