Trigger that only executes if the item receives a item for the first and stops after

[Tavares]

I have this trigger count(/Cisco IOS SNMP/system.descr[sysDescr.0],15m)=1 with a discard with an unchanged heartbeat of 12 hours but it keeps triggering and i dont know why.

[AlexeyBrizgalov]

Hi,

This is a very strange trigger to use. What exactly do you need it for?
Count() function counts the number of values received in specified time frame. So as far as I understand, in your case trigger will fire if the number of values received within last 15 minutes is exactly 1.
Since Zabbix evaluates data for different items with a slight time shift to prevent huge spikes of data collection in the same moment, then something like this happens from my understanding:
1) Data collection occurs at 10:00:00 010ms;
2) At 10:00:00 011ms trigger is evaluated, 1 value was received, so condition is true and trigger is fired;
3) Data collection occurs at 10:15:00 001ms;
4) At 10:15:00 002ms trigger is evaluated, now there are 2 values received within last 15 minutes so problem is resolved.
5) Rinse and repeat.

[cyber]

Trigger likely has no discard with heartbeat option... it is the item that has it. You item collects a value, your trigger fires as it is instructed, but it will never go back to OK state ... trigger expression stays true, as new values are discarded and there is no recalculation of trigger (happens only, if any used item receives a new value). After 12h new value appears, but trigger is already in problem state so nothing happens...

Since Zabbix evaluates data for different items with a slight time shift to prevent huge spikes of data collection in the same moment,

this is also not true.. there is no built in delays... trigger (re-)calculation takes place when any used item receives a new value, everything just takes a little bit of time to reach from one process to another.. If you use several items in trigger and they all receive data with the slight delay, trigger will be recalculated multiple times, after each new value...