Thank you! It was an eye opener for me. We've been using slightly different approach (at https://jopilot.net) but vector database + langchain allows to process much bigger amount of data.
No problem! You could probably improve it by fine-tuning GPT models on different categories of documents, prior to doing the vector retrieval from embedding. Fine tuning isn't available for GPT-3-turbo or GPT-4 yet, so I am waiting to try out this hybrid approach for when it does come available.