RAGAS

HybridRAG: A Fusion of Graph and Vector Retrieval - Mitesh Patel, NVIDIA

Jul 22, 2025 · 20:24

Mitesh Patel, Developer Advocate Manager at NVIDIA, presents HybridRAG, a fusion of knowledge graph-based GraphRAG and vector-based VectorRAG for improved question-answering from complex texts. He emphasizes that ontology engineering consumes 80% of development time and is critical for accurate triplet extraction, where fine-tuning LLaMA 3.1 with LoRA boosted triplet accuracy from 71% to 87% on 100 documents. Patel also highlights retrieval strategies like multi-hop graph traversal, which provides richer context but increases latency, and recommends QGraph acceleration via Networx to reduce latency. For evaluation, he suggests RAGAS for end-to-end pipeline metrics and the LLaMA-Nimotron reward model for response quality. Ultimately, he advises using GraphRAG when data has inherent structure or complex relationships, but notes it is compute-heavy, so the choice between GraphRAG, semantic RAG, or hybrid depends on the use case.

The RAG Stack We Landed On After 37 Fails - Jonathan Fernandes

Jun 3, 2025 · 18:52

Jonathan Fernandes, independent AI engineer, details the RAG stack his team settled on after 37 failed attempts, covering orchestration (LlamaIndex), embeddings (BAAI BGE small), vector database (Qdrant), LLMs (GPT-4, Qwen, Llama), reranking (Cohere), monitoring (Arize Phoenix), and evaluation (RAGAS). He demonstrates a live prototype in Google Colab using a London railway knowledge base, showing how a naive RAG returns irrelevant results (e.g., suggesting black cabs for "where can I get help at the station"). By swapping components—replacing in-memory storage with Qdrant, using an open-source embedding model, upgrading to GPT-4, and adding Cohere reranking—the answer improves to "go to booth number five next to the Eurostar ticket gates." For production, he deploys via Docker Compose with NVIDIA embedding/reranking models and Ollama for serving. The episode also stresses the importance of tracing latency per component and using RAGAS for systematic evaluation across many queries.