Trigger setting question

[Bill Wang]

Timeline:
|T0_________|T1_________|T2_________|T3_________|T 4_________|T5_____|Ta_____| T6

The trigger started to evaluate values at "Ta", if everything went well, all item's data were retreived successfully from agent, the "#4" should mean the datas of "T5/T4/T3/T2". If there were no data received at "T4" due to some unexpected problems, what would "#4" really mean? "T5/T3/T2/T1"? Or still "T5/T4/T3/T2", but this time the evaluation failed, move forward to the next time to keep evaluation?

[BDiE8VNy]

Not sure whether I understand you correctly.

A trigger gets completely (re-)evaluated on every single value one of the items included in its trigger expression gets a new value. Well, except when time based trigger functions are involved, then it gets additionally evaluated every 30 seconds.

Depending on the respective trigger function #<n> refers either to the <n>th hindmost (received) value or to the last <n> (received) values. To be crystal clear: it does not refer to the <n>th expected value but to the <n>th value available in history resp. database.

[Bill Wang]

Not sure whether I understand you correctly.

A trigger gets completely (re-)evaluated on every single value one of the items included in its trigger expression gets a new value. Well, except when time based trigger functions are involved, then it gets additionally evaluated every 30 seconds.

Depending on the respective trigger function #<n> refers either to the <n>th hindmost (received) value or to the last <n> (received) values. To be crystal clear: it does not refer to the <n>th expected value but to the <n>th value available in history resp. database.

So if T4's value is unknown or missing, the trigger will evaluate T5/T3/T2/T1's values, right?

[BDiE8VNy]

Exactly! Well, at least almost.
In your context "#4" would mean v2, v3, v4, v5 (the last four values)


t0 t1 t2 t3 t4 t5
v1 v2 v3 v4 -- v5


Generally it depends on the context (trigger function). For some trigger functions it means the last <n> values and for others it means the <n>th value. So for instance "#4" in this example could also reference v2.