Hi there, I'm trying to optimize a slow query of this form:
(1 * avg_over_time(foo{instance=~"$i"}[$interval]) <= 10) or
(2 * avg_over_time(foo{instance=~"$i"}[$interval]) <= 20) or
(3 * avg_over_time(foo{instance=~"$i"}[$interval]) <= 30) or
(10 * avg_over_time(foo{instance=~"$i"}[$interval]))
I suspect it's slow because of the many duplicate calls to
avg_over_time(foo{instance=~"$i"}[$interval])
Is there some way to only call the avg_over_time function once and re-use
the results subsequently? I'm using Prometheus in conjunction with Grafana,
in case it's relevant.
The full query I'm trying to optimize is much more complicated, but I
figured the above would be enough to understand the problem. But in case
it's helpful, here is the full query I am trying to optimize (it's an Air
Quality Index computation):
((50 - 0) / (12 - 0) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
12) - 0) + 0) or
((100 - 51) / (35.4 - 12.1) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) > 12
and avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
35.4) - 12.1) + 51) or
((150 - 101) / (55.4 - 35.5) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) >
35.4 and
avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
55.4) - 35.5) + 101) or
((200 - 151) / (150.4 - 55.5) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) >
55.4 and
avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
150.4) - 55.5) + 151) or
((300 - 201) / (250.4 - 150.5) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) >
150.4 and
avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
250.4) - 150.5) + 201) or
((400 - 301) / (350.4 - 250.5) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) >
250.4 and
avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
350.4) - 250.5) + 301) or
((500 - 401) / (500.4 - 350.5) *
((avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) >
350.4 and
avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]) <=
500.4) - 350.5) + 401) or
clamp_max(avg_over_time(ambient_pm25_env{instance=~"$room.*"}[$aqi_interval]),
600)
Thanks for any help you can provide!
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