I Built a Hybrid Search Engine From Scratch — Here's What I Learned (LLM Zoomcamp 2026, Module 2)

I just completed Module 2 of the LLM Zoomcamp 2026 by @DataTalksClub — and this module completely changed how I think about search.

Module 1 taught me RAG and agentic pipelines. Module 2 taught me that the search step inside RAG matters far more than I realized — and that keyword search is only half the story.

Here's everything I built and learned.

What Is Vector Search and Why Does It Matter?

Traditional keyword search matches words. If you search for "enroll", it finds documents containing "enroll" — but misses documents about "joining", "signing up", or "registration" even if they mean exactly the same thing.