Technically our concept of "Index optimisation" maps to Elasticsearch's "force merge", so this should be easy to implement.

Documentation wise, we should make sure to point out that the need for optimisation is rarely real nowadays: an alternative would be to consider index optimisation a deprecated concept, however I think we can keep it for the sake of the minimal improvement it provides to people who deal with an index which really is meant to stay in "read only" for a long time, in which case it might still be a good idea to force the merge operation.

https://www.elastic.co/guide/en/elasticsearch/reference/2.x/indices-forcemerge.html