if _source is still 'warm' in transaction log and fields query parameter is specified, requested stored fields are extracted from _source (this happens even when _source is disabled).

This behavior is causing issues for me, as im trying to create external plugin that will allow indexing of computed/scripted fields. Computed fields are not present in _source, so when marking them as stored, they still cant be immediately retrieved using fields query parameter. They are available eventually after transaction log gets flushed.

It will be great if it will be possible to change this behavior or at least override it on index level.