[Rollups] Support selection of calendar or fixed interval in date histogram agg

[jen-huang]

Describe the feature:

Support changes in elastic/elasticsearch#33727, specifically for rollups.

ES UI tasks

• In Rollup Jobs wizard, allow users to choose calendar or fixed for their date histogram configuration.
  • This selection should only appear if their input would otherwise be treated as calendar.
  • For example, 1h would have previously been treated as a calendar unit, so ask the user if they want to treat it as a calendar or fixed interval, and write it to calendar_interval or fixed_interval based on their choice.
  • On the other hand, 2h is always treated as a fixed interval, so do not offer user the choice between units and just write it to fixed_interval.

Examples of resulting rollup job date histogram configurations:

Calendar:

delay: "1d"
calendar_interval: "1h"
time_zone: "UTC"

Fixed:

delay: "1d"
fixed_interval: "1h"
time_zone: "UTC"

Coerced (user didn't specify an interval type, so 1h is treated as calendar). We should continue supporting this for BWC, but new rollup jobs created with the revised Rollup Jobs Wizard should not have this format:

delay: "1d"
interval: "1h"
time_zone: "UTC"

Kibana App tasks

• Make sure that rollup index patterns created from a rollup index that has calendar_interval or fixed_interval in date histo aggs has the same information written to its typeMeta field
• Branch the logic of related visualization date histgram interval input based on the existence of either calendar_interval, fixed_interval, or interval. Some relevant files:
  • parseEsInterval
  • parseWithBase
  • leastCommonInterval
• Consider matching query with the field specified on the rollup job. For example, if the configuration is fixed_interval: "1h" and user inputs 1d, send fixed_interval: "1d" to the rollup search endpoint (instead of interval: "1d").
  • Some investigation should be done before implementing this. Per @polyfractal, sending mixed inputs (interval: "1d" in this case) should work, but we should think about what the user is going to want/expect when they query rollup docs.

[elasticmachine]

Pinging @elastic/kibana-app

[elasticmachine]

Pinging @elastic/es-ui

[cjcenizal]

Relates to #27410

[cjcenizal]

Note that when we make this change we'll also have to update the Rollup API integration tests so that they use rollup job payloads that mirror those produced by the UI.

[timductive]

Closing this because it's not planned to be resolved in the foreseeable future. It will be tracked in our Icebox and will be re-opened if our priorities change. Feel free to re-open if you think it should be melted sooner.