Hermetry keeps different levels of detail for different lengths of time. Raw readings are large and are kept short; summaries are small and are kept for the whole retention period. This page explains the retention classes and what you can still read at each age.
Retention classes
Your organisation’s device telemetry is written into one retention class. Each class keeps:
| Class | Raw readings | 1-minute aggregates | Hour and day rollups |
|---|---|---|---|
| 7 days | 7 days | 7 days | 7 days |
| 30 days | 7 days | 30 days | 30 days |
| 90 days | 30 days | 31 days | 90 days |
| 365 days | 90 days | 31 days | 365 days |
| 1,095 days | 90 days | 31 days | 1,095 days |
In short: raw readings are kept at most 90 days, minute aggregates at most 31 days, and hour and day rollups for the full class.
Which class you have
The class comes from your plan, not from a device or a profile:
- The plan states a telemetry retention in days. Hermetry uses the smallest class that covers it.
- The IoT tiers Starter, Growth and Scale set 365 days, so device telemetry is in the 365-day class: raw readings for 90 days, minute aggregates for 31 days, hourly and daily figures for a year.
- A plan that sets no retention uses the 30-day class.
- The class applies to the whole organisation and one kind of data (device telemetry). Every device and every profile shares it. You cannot keep one profile’s data longer than another’s.
What you can read at each age
With the 365-day class:
| Age of the data | What you get |
|---|---|
| Up to 90 days | Every reading (raw), and minute, hour and day figures where kept |
| 31 to 90 days | Raw readings and hour and day figures; minute figures are gone |
| 90 to 365 days | Hour and day figures only (sum, count, min, max, last per bucket) |
| Older than 365 days | Nothing |
A chart over the last year reads hourly figures, so it is unaffected. A table that lists every reading of a day five months ago is empty: those raw readings are gone. Plan exports and integrations with this in mind.
Old readings that arrive late
A reading older than the raw window of your class is refused when it arrives (too_old); it is not stored as a summary either. With the 365-day class, a device that replays a buffer older than 90 days loses that part. See Timestamps, late and duplicate readings.
When the plan changes
When your plan’s retention changes, new readings go into the new class from then on. Readings already stored stay in their old class until they age out there. Reads cover both, so charts do not break at the change. Data does not move between classes: moving to a longer class does not bring back raw readings that the old class already dropped.
Deleting data
- Deleting a device removes all its readings and summaries in the background.
- Closing your organisation removes all telemetry. See Export your data and close your organisation.
- There is no way to delete single readings or one key’s history from the console.
Keeping data longer
If you need every raw reading for longer than your class keeps it:
| Option | How |
|---|---|
| Pull it regularly | Read the raw values with the history API before they age out, for example every day for the day before. See The history API. |
| Forward it as it arrives | Add an HTTP request, MQTT out or Webhook block to the root flow after Save telemetry, sending each record to your own store. See Action blocks. |
| Keep summaries | For reports, the hour and day figures (kept for the full class) are usually enough. |
Other retention in the platform
| Data | Kept for |
|---|---|
| Alarms and their history | See Working with alarms |
| A flow’s run records | 24 hours |
| A flow’s log lines | 24 hours |
| A flow’s error log | 7 days |
| A flow’s lifecycle events | 30 days |
| Failed flow messages | Until replayed or discarded; at most 10,000 entries by default, the oldest trimmed first |
See Flow limits.
Settings
There is no retention setting for customers: the class comes from the plan. The only telemetry settings an organisation can change are the timestamp checks under Settings > Telemetry. See Timestamps, late and duplicate readings.