Support for Composite Aggregations in Kibana

[alexfrancoeur]

Some users would prefer that we use composite aggregations to avoid bucket explosion in the user defined aggregations. Canvas takes advantage of this by default through SQL, so it's possible we could support this in visualize (and Lens) natively.

Example:

User X was trying to build a typical line chart based on some value plotted over range, but wanted to keep the granularity of the points very low (i.e., plot lots of points) while using a large time range. Kibana currently increases the interval on the date histogram to avoid a bucket explosion in the generated aggregations. But since 6.1 and composite aggregations, it seems like we could remove this restriction and simply switch to using a composite aggregation at a certain threshold of buckets, or date range?

[elasticmachine]

Pinging @elastic/kibana-app

[timroes]

I'll close this as a duplicate of #26528 (which tracks composite in tables) and #34022 (which will support pagination and from talks I had with @lukasolson so far, we're also planning to have the new courier support pagination on aggregated results).