[Star tree] Star tree test cases / bugs tracker

[bharath-techie]

Is your feature request related to a problem? Please describe

This will the single issue where we can track all star tree related test cases, edge cases, potential bugs etc as we develop the feature.

Describe the solution you'd like

Address them as part of tests

Related component

Indexing:Performance

Describe alternatives you've considered

No response

Additional context

No response

[bharath-techie]

Need to add a separate issue for tracking performance issues

But using this issue to track open items in case of performance cases / test cases for now :

1. https://github.com/opensearch-project/OpenSearch/pull/14817/files#r1698084827 - Measure IO performance for mergeFiles logic in off heap star tree builder.
2. Benchmark the number of nodes created in memory in off heap.

[bharath-techie]

3. Add randomness to builder tests - data type of the dimensions and metrics should be random, range should be random, null,0 should be heavily skewed etc.

[bharath-techie]

4. Measure the performance of on heap vs off heap and see if there are any scenarios on heap is helpful and also the tradeoffs in terms of higher memory utilization against performance gain.

[bharath-techie]

Bug : Handle docs with -1 as value : #15097