Custom alarm fired multiple times

Hi folks. I've set a custom alarm using the 'batteryLevel' attribute, like this:

batteryLevel < 20 ? "lowBattery" : null

How can I limit the number of times it fires the notification? Just as it is I get multiple notifications as devices move and send data continually.

There's no way to limit it, as far as I know. You will receive an alarm every time it's triggered.

Is there a way to create an attribute using sql? Maybe I could check in the db that the alarm for today has been already generated. If I could then reference this attribute in the alarm it would fire only one time per day.

Computed attributes don't really have access to historical data.

Well, I guess it's better to see the volume of notification as a stronger reminder to charge the device. :)

Thanks!