Hi Daniel, depending on how you decide on the list of ids, in the first place, you could also create a new index (core) and populate it with DIH which would select only documents from your main index (core) in this range of ids. When updating you could try a delta import.
Of course, this is only worth the effort if that core would exist for some time - but you've written that the subset of ids is constant for a longer time. Just another idea on top ;-) Chantal
