[META] [Star Tree] [Search] Supported Queries to resolve via star tree

[sandeshkr419]

Please describe the end goal of this project

This issue keeps a tracker of supported aggregations & query shapes which can be resolved via star-tree composite indices and the star-tree implementation (if possible) should benefit the performance for the query shape.
This will basically keep a track of supported and planned query shapes which can utilize star-tree aggregation for faster computation.

As for 2.17 release, only numeric fields are supported in star-tree composite indices. The list will be updated as we identify more query shapes that we can pick up.
Community - Please do share/comment on what all you think should be prioritized.

Here is the brief segregation on milestones:

Milestone 1: The primary goal of Milestone 1 is to utilize star-tree to resolve metric aggregation queries (max, min, avg, sum, value count) over numeric fields along with support of a single query as well. This milestone lays out the building blocks of how star-tree approach can be integrated in within a search request to resolve it.

Milestone 2: The primary goal of Milestone 2 is support certain queries within above aggregation requests like term/terms query, boolean query over numeric/keyword fields.

Milestone 3: The primary goal of Milestone 3 is to support single-level bucket aggregations like date histogram, range aggregations, single bucket aggregations, etc

Milestone 4: The goal of this milestone is to extend the star-tree support to resolve nested aggregations, multi-terms aggregations.

Milestone	Query Shape	Status	Target Release	Issue	PR
1	Metric Aggregation	Merged	2.18	#14871	#15289
1	Metric Aggregation with numeric field term query	Merged	2.18	#14871	#15289
2	Metric Aggregation with keyword field term query	Not Started	2.19	#16537
2	Metric Aggregation with IP field term query	Not Started	2.19	#16547
2	Metric Aggregation with multi-terms numeric/keyword query	Not Started	2.19	#16538
2	Metric Aggregation with numeric range query	Not Started	2.19	#16539
3	Bucket terms Aggregation with metric aggregation	Not Started	2.19	#16551
3	Date histogram with metric aggregation	Not Started	2.19	#16552
3	Range aggregation with metric aggregation	Not Started	2.19	#16553
4	Multi-terms aggregation	Not Started	(TBD)
4	Nested bucket aggregation	Not Started	(TBD)

Related component

Search:Aggregations