Lens Formula subtract first and last document

Elastic Stack Kibana
,
1

I want to subtract the last and the first document from a timerange to check how much engergy was consumed. So i make a lens with a formula like this :
(last_value(value.value_float32) - min(value.value_float32)) . I take the min value because it seems there is no function for the "first" document. The syntax works, but only for ca. 11 hours.

11h
11h903×478 24.6 KB

After that, the result of the min document is zero. so the visualtion will shw the "last" document. I checked the documents after 11 hours and there is no one document with a zero.
12h
12h913×478 25 KB

I also checked with other documents. Same result... So I don't get it, where my mistake is, or is it a bug? Maybe there is a another solution?

Greetz Thomas

Edit: I m working withe the Version 8.6.1

2

Hi @deepack86

welcome to the Kibana community.
In Kibana 8.7 the "previous" shift feature has been introduced which will allow you to perform a difference between the last value of the current time window and the previous one:

last_value(value.value_float32, kql='value.value_float32: *') - last_value(value.value_float32, kql='value.value_float32: *', shift='previous')
3

Hi Marco_Liberati,

thanks for your anwser! It works ver well... : )

Greetz Thomas