Samba now has an experimental Spotlight backend using Elasticsearch as fileindex. It seems that creating a similar backend could also be something that could be useful to investigate in the context of the windowssearch feature for samba
I only know less than zero about elasticsearch other than it is a popular and scalable indexer, it's been on my todo list a long time to findout more about what it does and do some prototyping to see if something similar to the spotlight work in this area would also be applicable for the windows search work. It would at least require me to forward port my windows search stuff (which has stagnated) and additionally rewrite some of it do a some prototype work
This project is one of its kind!