Nit: the drawback of “not working well in disk based systems” isn’t a drawback unless you’re already using disk based systems.

The difference in recall is also significant — what you really get with HNSW is a system made to give good cost:approximation quality. These IVFPQ based systems are ones I’ve seen people rip and replace if the use case is high value.

I really don’t understand the push to make pg do everything. It wasn’t designed for search, and trying to shove these features into the platform feels like some misguided cost optimization that puts all of your data infrastructure on the same critical path.