[Lens] collapse by only one field for multi-field top values

[drewdaemon]

Describe the feature:
Collapse-by is currently only be applied at the dimension level. We could consider allowing it to be applied more granularly.

[elasticmachine]

Pinging @elastic/kibana-visualizations @elastic/kibana-visualizations-external (Team:Visualizations)

[joshdover]

This is important for counter metrics where you need to be able to calculate the rate within the individual dimensions first, before summing to receive a total. Without the ability to collapse on a subset of the breakdown metrics, you can only provide a summed total across all dimensions, rather than maybe only on 1 of them.

My current example is ingest pipeline metrics. These are reported as counters on a per-ES-node, per-pipeline basis. So I need to calculate the counter_rate on those two breakdowns, however I'd like to be able collapse only on the node dimension, and retain the pipeline dimension. This is currently possible with Tables in Lens but not Line or Bar graphs.

Related to elastic/integrations#4597

[joshdover]

The good news is that I don’t think the technical implementation here is going to be reinventing anything, as we already support this in Tables, just not in time-series charts like Line and Bar. I think the initial challenge to getting this done is likely to be the UX design of how to present this in the UI.

I think we should explore copying how Lens Tables presents breakdowns (which are labelled "Rows") by having each breakdown field be a separate pill in the top-level Lens menu, rather than being grouped into a single "top values":

[stratoula]

• 1 https://discuss.elastic.co/t/kibana-query-problem/337671/4

[markov00]

In order to provide better transparency of priorities, issues that will not be prioritized within the next 24 months are being closed.

Tracking request in Lens general improvements ice box #184459