Earlier quoted context omitted.
You are glossing over the fact that for RAG you need to search over those 500GB+ which will be painfully slow and CPU-intensive. The goal is fast retrieval to add data to the LLM context. Storage space is not the sole reason to minimize the DB size.
You’re not searching over 500GB, you’re searching an index of the vectors. That’s the magic of embeddings and vector databases. Same way you might have a 50TB relational database but “select id, name from people where country=‘uk’ and name like ‘benj%’ might only touch a few MB of storage at most.
The LEANN author proposes to create a 9GB index for a 500GB archive, and the other poster argued that it is not helpful because “storage is cheap”.