How does Data Backfill work?

Data Backfill is a feature that is available optionally for our Temperature sensors and is a standard inclusion for our Temperature Probe sensors.

Where to use?

Data Backfill operates reliably in stable and permanent installations, with good and reliable connectivity as a requirement. However, in environments characterized by unstable and unreliable connectivity or use cases demanding mobility of either the sensor or Cloud Connector, Data Backfill isn't guaranteed to function. 

Data Backfill primarily functions as a safety measure, designed to safeguard against data loss during service interruptions, power outages, and comparable situations that could result in data loss.

It is not intended for use as a data logging option where periodic disconnections between the sensor and Cloud Connector are deliberate and planned as a use case.

How does it work?

If the sensor goes offline, it will start storing temperature measurements locally until the connection to the cloud is restored. The sensor will then start backfilling data, starting with the most recent samples first. The sensor will overwrite the oldest data if the memory becomes full.

The number of data points that can be stored in an offline period depends on the sampling rate, heartbeat configuration, and temperature fluctuations.

It takes at least two heartbeats for backfilling to start after sensor reconnection to the Cloud Connector:

  • One to trigger the retrieval request
  • Another for the sensor to respond. 

Whether the reported Temperature event was due to Backfill or not is currently only visible through the API. The event contains a field called isBackfilled and is documented in our Developer Docs. This is not yet available in Studio.

How long does it take?

Assuming flawless communication and already initialized backfilling, 20 backfilled heartbeats (HBIs) per 1 live HBI is the best-case scenario. However, message loss can occur, causing delays in backfilling, especially with longer heartbeats.

The backfill duration remains unaffected by the sampling rate.

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