When a RAG system needs fast, accurate document retrieval without relying on semantic embeddings, Lucene offers a practical alternative. It indexes documents, retrieves the most relevant results for a user query, and leaves response generation to a specialized natural-language component. section 6.3.2
A Lucene-based RAG flow separates retrieval from generation:
- Index the document repository with Lucene. section 6.3.2
- Retrieve the most relevant documents or passages for the user query. section 6.3.2
- Pass the retrieved content to a generator that produces a coherent response. section 6.3.2
Choosing retrieval over embeddings
For a text-only organizational document set, Lucene can retrieve relevant content directly instead of first splitting documents into chunks and embedding them. This favors retrieval accuracy and speed, while nuanced, human-like responses remain the generator’s responsibility. section 6.3.2
