PROMQL: Calculate the sum_over_time of the product of two instant vectors

Question

I want to calculate the sum_over_time of the product of two instant vectors:

How can I get this to work?

I tried to use:

sum_over_time((metric_a{label1:"A"} \* metric_b{label1:"A"})\[30d\])

but I received the error message "ranges only allowed for vector selectors"

Answer 1

You need to use Subquery:

sum_over_time((metric_a{label1='A'} * metric_b{label1='A'})[30d:])

(pls note that a default resolution/step is used in the example, you might want a custom one for your query)

---

In Prometheus, you can do this to get a range vector:

metric[1m]

However, you cannot do this with expression:

(metric)[1m] ---> parse error: ranges only allowed for vector selectors

Instead, a subquery should be used:

(metric)[1m:]