This background process is launched on demand, when you use the import historical data feature of Weather Station after choosing “Netatmo cloud services” as source.
The process query Netatmo cloud services to retrieve old records. It is done on 21 days timeframes. Records are retrieved on a 30 minutes steps basis and all indexes you’ve set are recomputed for each day in the set period. After the process is correctly terminated, all data and indexes are stored in the Weather Station database tables and available for use in historical charts and controls.
I do not recommend to try to use this data until the process is completely finished. Indeed, Weather Station caches are flushed only at the end of the operation, and before that, you could obtain or display erroneous values.
You can follow the progress of this process in the “At a glance” box of the Weather Station dashboard. Be warned that this progress can be very slooooow…
This process may take from hours to days. It has been optimized to not exceed the Netatmo API quota. It does not interfere with the operation of your server and you are notified by email of the end of treatment.