The summary.
CALCULATE COST PER DEVICE PER YEAR AT PROJECTED SCALE
Per-message charges accumulate faster than people expect, in foreign currency.
QUEUE BETWEEN INGESTION AND PROCESSING
Devices cannot be told to stop, so the platform must absorb bursts — sized for the reconnection flood after a widespread outage.
Check that the reported device identifier matches the authenticated one, or a device can report as another.
LATE AND OUT-OF-ORDER DATA IS NORMAL IN IOT, NOT EXCEPTIONAL
Devices buffer during outages and then send history. Process by event time, never arrival time.
DOWNSAMPLE AS DATA AGES AND NEVER USE UNBOUNDED VALUES AS TAGS
Nobody queries second-level detail from two years ago, and high-cardinality tags degrade time-series performance badly.
COMPARING A DEVICE WITH ITS NEIGHBOURS SEPARATES SENSOR FAULTS FROM REAL CONDITIONS
Without needing a reference instrument. And fixed thresholds without seasonality alert every morning.
ALWAYS DISPLAY WHEN A VALUE WAS READ
Stale data presented as current causes wrong decisions.
