Previously I’ve used the default Elasticsearch release that includes cosineSimilarity functionality as part of the x-pack. I was able to run a normal keyword query and then multiply the keyword _score by a similarity score using a painless script (_score * cosineSimilarity(v1, v2)).
I have not figured out how to do the same thing with the KNN implementation. I see that additional functions can be provided to re-weight the KNN score, but I don’t see how to multiply the score from a basic keyword query with a KNN similarity score.
Is this kind of usage intended? If not, is there a workaround?