[TSVB] Legend doesn't indicate which series name is being shown, just the split value

[wylieconlon]

TSVB should have the same legend behavior as Visualize when showing duplicate values across different series. Instead, it shows a legend which doesn't indicate the source of any value:

Example workflow:

1. Group by the Top 10 Terms of a field
2. Create a second layer with the same Group By setting
3. Configure different metrics, such as "average cpu" vs "max cpu"
4. They look the same

Expected result, showing unique names for each series:

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[timroes]

@markov00 is this something you consider us fixing inside TSVB, or should this rather be addressed on elastic-charts level?

[markov00]

@timroes I think this should be done directly in TSVB as a default way label the series, is not an issue of charts, but the desired series name should be sent to elastic-charts from TSVB, we just render the configuration prodived.

[markov00]

There are multiple ways to change the series name in elastic-charts: https://elastic.github.io/elastic-charts/?path=/story/stylings--custom-series-name https://elastic.github.io/elastic-charts/?path=/story/stylings--custom-series-name-config https://elastic.github.io/elastic-charts/?path=/story/stylings--custom-series-name-formatting

[timroes]

I wonder if we would always want to show the metric name or only once we have at least 2 different metrics in there, so that it could actually lead to an ambigious legend. Marco or Wylie, any thoughts on that?

[nickofthyme]

I'm doing this for vislib. I think we could just throw that logic in the charts plugin and use it in tsvb. I can work on this after the vislib pr is merged.

[wylieconlon]

@nickofthyme That sounds best, the existing logic in vislib is working well. @timroes to answer your question, the existing behavior of vislib works fine for me, which is to only add the extra text when it's needed.

[nickofthyme]

@wylieconlon and @timroes I looked into this issue some more and I found that TSVB allows multiple "compounding" aggressions/metrics for a single layer (e.g. Count of Max AvgTicketPrice). Whereas in vislib you can only have one AFAIK. This makes it hard to put this aggression into a human readable string like Max AvgTicketPrice to be used in a label such as ES Air: Max AvgTicketPrice, as done in vislib.

But we currently allow the key to be used in the layer title with a user defined value. Thus labeling the series with Series 1 - {{key}} and Series 2 - {{key}} produces something like this...

This way the series are discernible to the user without the need to determine the combined human readable aggregation.

I think if anything we could just combine the aggregations and use that when there is more than one layer but to me using the {{key}} title seems like a much better option that is already in place.

[timroes]

@nickofthyme ++ on the {{key}} approach. Will also prevent any breaking changes on charts in this case.

[nickofthyme]

Ok cool. In that case, I'm gonna close this issue. Anyone feel free to re-open if you think it needs a better solution.

[nickofthyme]

To be clear this code is here

https://github.com/elastic/kibana/blob/3c99839cf7a624e7a8201f8636ae8c9b10cd8a9c/src/plugins/vis_type_timeseries/server/lib/vis_data/helpers/format_key.js#L20-L25

Looks to be added here (https://github.com/elastic/kibana/pull/11266) in v5.5.0.