Add min_doc_count support to range aggregations

[halilim]

Currently, range aggregations doesn't have min_doc_count support AFAIK. As a temporary solution client-side filtering could be used but being able to filter out empty buckets from range aggregations (and from other aggregations if possible) would be neater.

[jpountz]

This is something we started discussing on #8110. The issue has been closed since it probably had too much scope, but essentially we are thinking/working on adding the ability to do more stuff at reduce time (when all shard responses get merged) and filtering of the reduced buckets could certainly be done this way. Hopefully this would also allow to have a single way to filter buckets instead of having to implement it for every aggregation.

[clintongormley]

@colings86 any thoughts about this?

[colings86]

With the addition of the bucket selector pipeline aggregation in 2.0 you can now filter buckets of any aggregation type at reduce time for minimum doc count or any other criteria

[clintongormley]

thanks @colings86 - closing