MongoDB

Information Retrieval from the Ground Up - Philipp Krenn, Elastic

Jul 27, 2025 · 1:48:07

Philipp Krenn of Elastic demonstrates that vector search is only a feature of information retrieval, not its foundation, in this hands-on workshop on retrieval for RAG. He contrasts classic keyword search—using tokenization, stemming, stopword removal, and BM25 scoring with the inverted index—with sparse (Elser/Splade) and dense (OpenAI text-embedding-small) vector embeddings. Krenn explains why hybrid search, combining lexical and semantic methods via reciprocal rank fusion (RRF), outperforms any single approach, especially for brand or exact-match queries where keyword search remains superior. He also covers scoring normalization, chunking strategies, and the new `text_similarity_reranker` retriever, showing how Elasticsearch's retrievers API enables two-stage retrieval with a cross-encoder for re-ranking. The session emphasizes that retrieval quality depends on evaluating against a golden dataset or LLM-as-judge, and that 'it depends' is the correct answer for choosing between PgVector and dedicated search engines.

Building Multimodal AI Agents From Scratch — Apoorva Joshi, MongoDB

Jun 27, 2025 · 36:58

Apoorva Joshi, an AI developer advocate at MongoDB, leads a hands-on workshop on building multimodal AI agents from scratch. She defines agents as systems using LLMs to reason, plan, and execute tasks with tools, contrasting them with simple prompting and RAG. The workshop focuses on processing mixed-media documents (text and images) by converting each page to a screenshot, embedding it with Voyage AI's multimodal (VLM-based) model to avoid the modality gap of CLIP, and storing embeddings in MongoDB for vector search. The agent uses Google's Gemini 2.0 Flash as the multimodal LLM, implements REACT (reasoning and acting) for planning with feedback, and manages short-term memory via session IDs. Participants build a tool-calling agent that retrieves relevant page screenshots, passes them with conversation history to Gemini, and generates answers for queries like analyzing charts or extracting insights from documents.

Case Study + Deep Dive: Telemedicine Support Agents with LangGraph/MCP - Dan Mason

Jun 22, 2025 · 1:56:13

Dan Mason of Stride presents a case study on building autonomous agents for telemedicine support, replacing a human-driven button-pushing workflow with LangGraph, Claude, MCP, and a Node.js/React/MongoDB stack, achieving roughly 10X capacity increase. The LLM-driven virtual operations associate ("Ava") assesses patient messages, updates state with anchors and scheduled messages, and passes proposals to an evaluator agent that scores confidence and complexity, escalating to humans below 75% confidence. Mason explains how treatment "blueprints" in Google Docs are read directly by the LLM instead of using RAG, enabling new treatments to be added without writing code. He details the eval system using LLM-as-a-judge via PromptFu and retry logic for tool-calling errors, and discusses trade-offs around confidence scoring, prompt caching, and model selection (Claude for steerability). The team includes two software engineers, one designer, and Mason, who wrote most LangGraph code with AI assistance (Kline).