Even without a subquery, a rule can include a range vector expression and then reduce it to an instant vector, e.g.
expr: avg_over_time(snmp_scrape_duration_seconds[5m]) >= 3 On Saturday 3 February 2024 at 16:04:56 UTC Ben Kochie wrote: > All rule evaluations are instant queries. You do all the "reducer > functions" in PromQL itself. > > For example, you can use subquery syntax to do something like > `avg_over_time()`. > > On Sat, Feb 3, 2024 at 5:02 PM 'Andrew Dedesko' via Prometheus Users < > [email protected]> wrote: > >> Hi, >> >> I'm wondering whether prometheus uses instant queries or range queries >> when evaluating alert expressions? The context about why I'm asking might >> help clarify my question. >> >> I'm comparing Grafana Cloud's alerting functionality with prometheus. >> From Grafana Cloud we're querying Google Cloud Metrics with PromQL (it's >> Google's Monarch DB with a PromQL interface). Grafana Cloud's alerting >> system takes your PromQL query and performs a *range query* against >> Google Cloud Metrics, returning multiple data points over the range you >> have selected (e.g. 10 minutes ago to now). Then you need to choose a >> reducer function to turn the time series into an instant scalar (e.g. min, >> max, last, mean). >> >> Prometheus alerts don't seem to have an option for specifying a range and >> also don't have a reducer option. So this leads me to believe prometheus >> uses instant queries to evaluate alert expressions. But I'd like to know >> for sure. >> >> Thanks for reading! >> >> Here's the Grafana Cloud documentation on alert query ranges and reducers: >> >> https://grafana.com/docs/grafana/latest/alerting/alerting-rules/create-grafana-managed-rule/ >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Prometheus Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/prometheus-users/ef0e2ee6-a32e-479e-bbe4-10499372715cn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/prometheus-users/ef0e2ee6-a32e-479e-bbe4-10499372715cn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "Prometheus Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/prometheus-users/12386cd6-b032-45a6-b755-f0f51551b5d3n%40googlegroups.com.
