Maybe not full full text search, but you'll generally want to remove the duplicates and suchlike.

I guess you want some fast extra storage for as long as it takes to run https://github.com/chatnoir-eu/chatnoir-copycat but that's a very temporary thing.

my guess is mistral is so good for its size because they are doing some real precise pre ingestion selection and sorting. You need FTS to do that work.