R in RAG is for retrieval… of any kind. It doesn’t have to be vector search.
A search is a search. The architecture doesn't care if it's doing an vector search or a text search or a keyword search or a regex search, it's all the same. Deploying a RAG app means trying different search methods, or using multiple methods simultaneously or sequentially, to get the best performance for your corpus and use case.
> The architecture doesn't care
The architecture does care because latency, recall shape, and failure modes differ.
I don't know of any serious RAG deployments that don't use vectors. I'm referring to large scale systems, not hobby projects or small sites.