Jay Deng

Renaming this issue to focus on the bug specific to terms aggregations. I think there is still some work aside from that we can do to make the `search.max_buckets` setting...

> One scenario where I see this functionality is needed is if query collecting results at the coordinator level node and needs to support existing aggregations of core OS. @martin-gaievski...

@martin-gaievski Thanks for the details! I don't want to derail the conversation too much from @reta's original concerns but I do want to re-iterate my concern that all aggregations may...

> if we call IndexSearcher.search(Query, CollectorManager) then there will be exception throwing from [DefaultSearchContext.getTargetMaxSliceCount()](https://github.com/opensearch-project/OpenSearch/blob/main/server/src/main/java/org/opensearch/search/DefaultSearchContext.java#L979-L980), this is because two core aggregations `sampler` and `diversified_sampler` do not support concurrent search (this has...

@kkewwei thanks for opening the PR, it looks like the existing nested agg integration tests are failing after your change, could you please take a look? https://build.ci.opensearch.org/job/gradle-check/37514/#showFailuresLink Also would you...

Thanks @kkewwei, could you add an entry to [`CHANGELOG.md`](https://github.com/opensearch-project/OpenSearch/blob/main/CHANGELOG.md) for this as well?

Other than that I think this PR looks good to me, @msfroh @reta mind giving a maintainer review here as well?

Thanks @kkewwei , could you try to rebase from `main` to see if that fixes the flaky tests? We need to get the checks to green to be able to...

@reta @msfroh @andrross would one of you be able to give a maintainer review here? Thanks!

Thanks @reta! At a glance it looks like the failed assertions in this test are related to the request cache which should not have anything specific to concurrent search. I...