The documents are encoded as vectors and stored in a database, so I suspect it would be effectively unlimited. You would just pay for storage and compute.

AWS OpenSearch has fairly good integration so you could look up costs for that. It’s not the cheapest AWS service to run and not exactly serverless as you pay by the hour.

Even if you could, the problem is that these documents are first chunked into smaller pages, and then embeddings are created. When you ask a question, the algo searches for relevant chunks and passes them to the LLM's overall prompt. If there are too many chunks, or too many chunks with similar content, the search also coupled with the LLM's limited context window would mean only 1-3 chunks get passed.

This isn't the same as the training data the LLM is trained on. As a result, it doesn't take advantage of the entire document set. So, if you have a billion documents, only 1-3 chunks will be picked for the final answer. When you know a question spans many many documents, the answer is never going to cover that.

You could make a recursive also where you parse all the chunks, generate summaries of those and then pass them to the next chunk sequentially and so on. But you can imagine how expensive and slow that will be. It might still work for you but this is a very lossy approach.