It's true that I'm just an university student and you are a scientist, a researcher, a professor, and an enterpreneur, but it doesn't mean that I can't be knowledged as you in very narrow fields. I'm currently running a personal project that uses Lucene since four years ago, with about 8 billion messages and 340 million chats stored in a distributed lucene index, so I'm not the regular troll or a person that just talks without knowing anything. I surely can't critique your T-WAND algorithm, that it seems to be good in your use case, but with all the humilty in the world I can say to have the minimum knowledge required to spot some weird usages of Lucene APIs.