History, Trends & Housekeeper

[safpsr]

Hello,

I have a small question about the trends, history & housekeeper. History tables contain the values of all items, a table for each type of item.
The trends tables contains calculated items ( average / min / max ), one per hour.
At what time are calculated the trends values ?
- When the housekeeper runs and cleans out of date values from history ( once per hour by default )?
- Every time the server receives a value for an item from the agent ? If it receives a value per minute for an time, does it calculate average / min /max 60 times per hour ?
- At another time by another process?

Thank you for your help.

[heaje]

I seem to recall that the trends are calculated every hour by some zabbix process (not the housekeeper). I'm not 100% certain though.