[Discover] Format rolled up metrics correctly in doc table

[flash1293]

Rolled up metric fields in TSDB indices will not return a single number, but a stats object - instead of

  myField: [4]

it will look like this:

  myField: [{ min: 0, max: 3, sum: 12, count: 17 }]

Discover should detect this case and render the object in the doc table in a nice way (as JSON or maybe with the existing _source formatter)

How to start development

• Check out https://github.com/elastic/elasticsearch/tree/kibana-downsampling-branch next to your kibana working copy
• Start ES with yarn es source instead of snapshot (this will build the given branch)
• Clone https://github.com/csoulios/downsampling-demo
• Run the commands in downsample-index.es (indexing the actual data is too much for dev console, so you have to do this via curl curl -XPOST http://elastic:changeme@localhost:9200/sample-01/_bulk\?pretty -H 'Content-Type: application/json' --data-binary @sample-01-raw.json)
  After running all commands, there should be sample-01-rollup which has the rolled up data

[elasticmachine]

Pinging @elastic/kibana-data-discovery (Team:DataDiscovery)

[jughosta]

Hi @flash1293
Could you please provide some steps how we can recreate this state locally and to see metric fields on Discover page? Thanks!

[flash1293]

Hi @jughosta , this isn't done yet from the Elasticsearch side, but AFAIK @csoulios is actively working on it right now. @csoulios is there already a PR to link to or something?

[csoulios]

@csoulios is there already a PR to link to or something?

I haven't pushed a PR yet. I will add a link here when I submit the PR.

[csoulios]

@salvatore-campagna pushed PR elastic/elasticsearch#88534 to support this from ES side.
However, this is a breaking change so it takes some time to merge into master