Calculated item with function "last" and time shift

[josoko]

Hello

I do not understand how I can use the time shift for a calculated item, to calculate the change in % from the last value with a value which Zabbix has collected 1h (or 3h, or 1day) before the last value.

Origin Item:
- name: Value XY
- key: value[xy]
- interval 5m

This item below is working fine.

Calculated Item:
- name: Change in % Value XY
- key: ci.valuechange[xy,5m]
- calculation: round(((last(//value[xy]) - last(//value[xy],#2)) / last(//value[xy],#2)) * 100,4)

This item below is not working and I cannot figure out why. All calculations failed.

Calculated Item:
- name: Change in % Value XY
- key: ci.valuechange[xy,1h]

calculations:
round(((last(//value[xy]) - last(//value[xy],1h:now)) / last(//value[xy],1h:now) * 100,4)
round(((last(//value[xy]) - last(//value[xy],now-1h)) / last(//value[xy],now-1h) * 100,4)
round(((last(//value[xy]) - last(//value[xy],1h)) / last(//value[xy],1h) * 100,4)
round(((last(//value[xy]) - last(//value[xy],#1:now-1h)) / last(//value[xy],#1:now-1h) * 100,4)
round(((last(//value[xy]) - last(//value[xy],#1:1h)) / last(//value[xy],#1:1h) * 100,4)

I would appreciate it if somebody could explain to me, what's wrong with the time shift in my calculations,

[Markku]

This works for me:

round((last(//my_item)-last(//my_item,#1:now-1h))/last(//my_item,#1:now-1h) * 100, 2)

Your formulas have incorrect parenthesis I see.

Markku

[Markku]

I haven't used time shifts much at all but let's see according to the documentation.

https://www.zabbix.com/documentation...mon-parameters says that last() doesn't accept time spec, so your calculations 1, 2 and 3 are incorrect right away.

https://www.zabbix.com/documentation...ion#time-shift says that time shift starts with "now", so your 5 is incorrect.
That leaves 4 the only one that is correct by syntax (as far as I see it). I don't have direct answer why it doesn't work.

For me the whole concept of "last value 1 hour ago" is a bit vague. For example, if it is 11:00 at the moment and there are values at 09:59 and 10:01 (but not at 10:00), which one should it choose?

Markku

[Markku]

Btw, what does "All calculations failed." mean?

Markku

[Markku]

This works for me:

round((last(//my_item)-last(//my_item,#1:now-1h))/last(//my_item,#1:now-1h) * 100, 2)

Your formulas have incorrect parenthesis I see.

Markku

[josoko]

Markku , Indeed. It was an issue with the parenthesis. That works now:

round((last(//value[xy]) - last(//value[xy],#1:now-1h)) / last(//value[xy],#1:now-1h) * 100,4)

The origin calculation is wrong as well. It surprises me, that Zabbix has not dropped an error message here:

Wrong:
round(((last(//value[xy]) - last(//value[xy],#2)) / last(//value[xy],#2)) * 100,4)

Should be:
round((last(//value[xy]) - last(//value[xy],#2)) / last(//value[xy],#2) * 100,4)

Many thx! You solved my problem. Have a nice weekend!