Configuring PromQL query statistics

[puetzp]

Hey there, it is currently possible to retrieve query statistics using the stats query parameter. Since v2.35 query statistics of range queries can be extended with per-step data by running Prometheus with --enable-feature=promql-per-step-stats. When I'm not interested in per-step stats I simply need to pass stats with in arbitrary non-empty value, e.g. stats=foo. So the query parameters basically behaves like a boolean, see source:

func defaultStatsRenderer(ctx context.Context, s *stats.Statistics, param string) stats.QueryStats {
    if param != "" {
        return stats.NewQueryStats(s)
    }
    return nil
}

In the context of per-step stats however I need to pass stats=all in order to retrieve the data. So in the latter case the value matters and is pattern-matched in the handler:

func extractQueryOpts(r *http.Request) *promql.QueryOpts {
    return &promql.QueryOpts{
        EnablePerStepStats: r.FormValue("stats") == "all",
    }
}

I guess my question is if it does make sense to change stats to an enum and deny unsupported values since other endpoints already do this (e.g. /api/v1/rules with type=alert|record). I think that would make it easier for client libraries to reason about this parameter as well.

Feel free to close this issue when the matter has been discussed ad nauseam.

[roidelapluie]

Hello,

Unfortunately this is not possible within Prometheus v2. We could consider it for Prometheus v3.

[puetzp]

That would be great! By the way is there a place where ideas/discussions/issues are tracked for a future v3?