Calculate Max in value with prometheus

Question

Since I am prometheus-newbie I do not know how to express the question: "What is the maximum number of messages which have been processed per second during the last day". The metric is named messages_in_total

I tried

• max_over_time(messages_in_total{}[1d]) - but this returns the maximum of the counter value
• increase(messages_in_total{}[1d])- but this returns the number the counter increased

What I really need would be something like (pseudocode)

1. Transform range vector which contains absolute messages_in_total to a range vector with which has a value for each second.

2. get the max out out of it

Example:

• initial range vector values = (3000,4000, 7000, 8009)
• adjusted range vector values with rate for each second (values are guessed) = (40, 70, 40)
• max_value => 70 messages processed per second

Any ideas?

Answer 1

It is possible.

Example query:

max_over_time(
   irate( messages_in_total[2m] )[1d:1m]
)

This will:

1. take last 1 day
2. For every 1 minute in that 1 day range it will execute irate( messages_in_total[2m] )
3. Combine that into range vector
4. Call max_over_time on all results

See subquery documentation for more information!