Multiple references to the same index-pattern in a dashboard saved object

[MichaelKatsoulis]

Kibana dashboards when created following the by value approach, save a lot of references of the same index pattern in the saved object json file.

Does this make sense? The share the same id metrics-*. So why not just one?

[elasticmachine]

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

[dej611]

I think is mostly a @elastic/kibana-presentation issue, but it's more an optimization rather than a bug to me.
Each visualization is declaring its own references (as {name: <visualization_id>, etc...}) and the dashboard is moving them into a single references prop in the SO.

[drewdaemon]

I think the thing we want verified here is that all the data view references in the dashboard (you can see the full list here) are ultimately pointing at a single metrics-* data view. Is that right, @MichaelKatsoulis ?

[MichaelKatsoulis]

@andrewctate Yes and if all those are pointing to the same id then why not just have one reference?

[drewdaemon]

@MichaelKatsoulis, the presentation team is welcome to chime in, but since all the references point to the same data view with the id prop, you don't need to be concerned that there are more than one data view at play.

I assume that the reason there are multiple references is that it is simpler for the dashboard application to treat saved-object references within its panels as opaque. TBH, I'm not sure why it would be useful to optimize this.

[ThomThomson]

@MichaelKatsoulis, the dashboard extracts all references from each panel on save. Each dashboard panel could potentially be associated with many references, and because there is a registry of embeddable types, we cannot predict how many references, or what type of references will be extracted.

For instance, some panels (by reference) contain references to the visualize library, there can be references to other dashboards stored in drilldowns, and there are of course there are plenty of data view references. We store each reference in the references array with their panel index in the name so that when a dashboard saved object is loaded, we can inject them back into the correct panel.

This system does result in duplication in cases where many panels have the same reference, but it hasn't caused any issues so we haven't felt the need to de-dupe. Is there currently an issue being caused by the way dashboard references are stored?

[MichaelKatsoulis]

@ThomThomson it is not issue per se, it just looked strange to me that references with same id can be part of the dashboard if each one of them is not offering something new. I understand the need of multiple references of course in the list but not same ones.

If you believe that it is just a a necessary evil of the current implementation then we can close the issue.

[ThomThomson]

It's not strictly necessary to keep it this way. With enough effort, references could be de-duped without losing the connection between the panel and the reference - but the question is "is this feature impactful enough to justify that effort"? And I haven't personally seen justification that says it is.

[ruflin]

Thanks everyone for chiming in. My initial reaction was when I saw the list is, that there is a good chance that the same index pattern exists multiple times (an issue we had in the past). But it seems like it is not the case and more about internal management of references in saved objects. I don't think it is a requirement to improve this but this issue serves as a good documentation for this feature / behaviour as likely we are not the last integrations developers that have questions around it. I'm going to close this issue, lets reopen if needed.