Recording rules are a way to precompute frequent promQL queries, spreading the compute overhead over time, which increases Metering performance at query-time and reduces the query-time load on Prometheus.

In the case of Metering, we're periodically importing and storing a subset of Prometheus metric data based on a list of defined promQL queries here: https://github.com/kube-reporting/metering-operator/blob/master/charts/openshift-metering/values.yaml#L165-L257

This would involve updating that list of promQL queries to use the recording rules we define in the metering group.