Also, no way retrieval performance is going to match pgvector because you still have to join the external vector with your domain data in the main database at the application level, which is always going to be less performant.

i'll take a 100ms turbopuffer vector search plus a 50ms postgres-select-where-id-in over a 500ms all-in-one pgvector + join query.

When you only need to hydrate like 30 search result item IDs from Postgres or memcached i don't see the join being "too expensive" to do in memory.

For a large class of applications, the database join is the last step of a very involved pipeline that demands a lot more performance than PGVector can deliver. There are also a large class of applications that don't even interface with the database directly, except to emit logging/traceability artifacts.