query returning empty metric if functions are used

[zxwing]

I just notice if I use functions in an expression the response contains an empty metric, all labels are just lost. Is it by design?

My application relies on labels a lot, missing labels breaks the business logic.

Specific to my problem the function I use is avg()

[grobie]

I assume you mean in general aggregators and not functions here: https://prometheus.io/docs/querying/operators/#aggregation-operators. Aggregation operators by design combine multiple time series and produce new ones. If you don't specify a by() or without() clause they will collapse all time series into one. To avoid that, be more specific on which labels you want to make the aggregation happen.

Example: avg without(instance)(your_metric) will keep all labels except the instance label.

[zxwing]

@grobie thanks, it starts working now; however, the name metric is still missing, is there any way to keep it? I don't need to operate on multi-series.

[brian-brazil]

The name is only kept if it's still the same metric, for example x * 2 is no longer x so the name is removed.

[zxwing]

got you. Thank you!

[lock]

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