How to use the reduce functions in alert condition?

Grafana Alerting
1

In the documentation at Queries and conditions we have:

① Time series data — The query returns a collection of time series, where each series must be reduced to a single numeric value for evaluating the alert condition.

What is the purpose of the reduce functions¹ in the alert condition if you cannot get there with multiple values?

See Terraform: How to use the reduce functions in alert condition for more context.

¹ Which are documented below ①, I cannot have more than two links in my post since I am a new user.

2

How do you want to evaluate timeseries (e.g. 10,20,90,50,20) against your alert condition (e.g. >80) - should alert will be failing in this case or not?

No matter what you say, someone will always have a different opinion. That reduce will function will reduce timeseries to single value (e.g. last/min/max/avg/… of timeseries), so then it will be clear, which metric value will be used against alert condition.

I recommend to ask Grot about this topic if you need to know more details.

3

I replied in the original thread due to the context being missing here.