Stop Chunking Like It's 2022
Official Schedule Context
- Date/time: 2026-06-29 · 3:20pm-3:40pm
- Track/room: Search & Retrieval · Track 3
- Speaker(s): Yuval Belfer, Niv Granot
- Session type/status: session · confirmed
Official Description
Every RAG system bets everything on a single chunk size. 500 tokens? 800? Pick wrong, and half your
queries fail before they start. But here's what nobody tells you: all the picks are wrong; there is
no single chunk size that works for all queries. We ran oracle experiments across meeting
transcripts, story chapters, and TV scripts. The result? Queries disagree violently on what chunk
size works best - sometimes by 40 percentage points. Your "tuned" chunk size isn't a compromise;
it's systematic underperformance. In this talk, we'll expose why fixed chunking fails and show you a
dead-simple fix: index at multiple chunk sizes, aggregate at retrieval time using Reciprocal Rank
Fusion. No retraining. No LLM overhead. Just 1-37% better recall across benchmarks by letting
queries vote with their ranks instead of forcing them into one-size-fits-all boxes. Walk away
knowing exactly when your chunk size is sabotaging you - and how to stop leaving 20-40% of your
retrieval performance on the table.
Related YouTube Video
RAG Evaluation Is Broken! Here's Why (And How to Fix It) - Yuval Belfer and Niv Granot (speaker-match related prior/adjacent AI Engineer video; captions: English auto-captions).
Transcript Status
Related video transcript availability: English auto-captions. Treat this as supporting context, not a recording of this exact scheduled session unless later confirmed. Not fetched yet.
People
Notes
- Pending transcript synthesis when an official recording or confirmed matching video is available.
Supporting Slides
- youtube Ywl4LsvHKzU slides — extracted from the related public AI Engineer video.
Slide Evidence
- Slide-only cropped deck: youtube Ywl4LsvHKzU dense slides (7 viable slide images).
- Related slide/OCR pages:
- youtube Ywl4LsvHKzU dense slides
- youtube Ywl4LsvHKzU reconstructed slides
- youtube Ywl4LsvHKzU slides
- Slide-derived terms:
world,fifa,local,name,questions,same,future,wife,first,mother,schema,prob,answers,assuming,answer,lies,certain,chunk