The expression
max_over_time(job_count_by_service{service="ServiceA",
tenant="TenantA"}[1d])
gives an *instant* vector as its result. You should evaluate it at a
specific instant in time, and it will give you the maximum over the 24
hours up to that instant.
You shouldn't run this over a time range in Grafana. If you do, then
you'll get a set of maximums swept over that range. For example, if you
run it over a 6 hour range, then the first data point will be the maximum
from (now-30h) to (now-6h), and the last data point will be the maximum
from (now-24h) to (now)
Alternatively, you can run a regular query over a Grafana time range, and
get *Grafana* to work out the maximum over that period.
On Saturday, 26 August 2023 at 09:45:40 UTC+1 Raghu c wrote:
> I am tracking the number of jobs in a queue at specific time intervals
> using a gauge metric. Prometheus scrapes this every minute.
>
> However, when I attempt to determine the highest number of jobs in the
> queue on a given day using the max_over_time query, I receive two distinct
> values for the same day based on different time ranges.
>
> I am using the query
> max_over_time(job_count_by_service{service="ServiceA",
> tenant="TenantA"}[1d]). When I run this query for a 1-day time range (from
> 2023-08-19 00:00:00 to 2023-08-19 23:59:59), the value I get is 38.
> However, when I run the same query for a 5-day time range (from 2023-08-18
> 00:00:00 to 2023-08-22 23:59:59), the result for Aug 19th is 35.
>
> 2023-08-19 00:00:00 to 2023-08-19 23:59:59 [Range Selected in Grafana]
> [image: RSxCO.png]
> 2023-08-18 00:00:00 to 2023-08-22 23:59:59 [Range Selected in Grafana]
> [image: gmW3m.png]
>
> In Grafana I have configured the Min Step as 1d and Type as Range. I'm not
> sure whether that could affect the values in any way.
>
> I assumed that max_over_time would pick the max value among all the values
> that fall in the range vector specified time period. For example, if on Day
> 1 the values are [1,2,7,6,5] and on Day 2 the values are [8,1,2,3,1] then
> the query would return 7 & 8 respectively for each day.
>
> To elaborate when I select 2023-08-19 00:00:00 to 2023-08-19 23:59:59 as
> the time range the values from 2023-08-18T00:00:00.000 ...
> 2023-08-19T00:00:00.000 is considered to pick a maximum. When I select the
> time range 2023-08-18 00:00:00 to 2023-08-22 23:59:59 won't the same values
> again be considered for picking the maximum since the range vector is 1d?
> So how can the value change from 38 to 35?
>
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