Indexing, Filtering & Hybrid Search
Make vector search fast and precise at scale by understanding index types, combining metadata filters with similarity, and blending keyword and vector retrieval with hybrid search.
Indexing, Filtering & Hybrid Search is a free LLM Apps in Production (RAG + Vector DB + Caching) lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the LLM Apps in Production (RAG + Vector DB + Caching) learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
The Scale Problem
Comparing a query against millions of vectors one by one is too slow for production. Vector databases use indexes to find near neighbors quickly without scanning everything.
Approximate Nearest Neighbors
Most vector indexes are approximate (ANN): they trade a tiny bit of accuracy for huge speed gains. For RAG, near-perfect recall at fast speed is a great deal.
HNSW Indexes
HNSW (Hierarchical Navigable Small World) is a popular graph-based index. It navigates layers of connections to reach neighbors fast, balancing speed and accuracy via tunable parameters.
IVF Indexes
IVF clusters vectors into cells; a query only searches the closest cells. The nprobe parameter trades recall for speed by controlling how many cells to check.
Metadata Filtering
Pure similarity can return the wrong scope — old versions, other tenants. Storing metadata with each vector lets you filter results to the right subset.
results = store.similarity_search(
query,
k=4,
filter={'tenant': 'acme', 'lang': 'en'}
)Pre vs Post Filtering
Filters apply two ways:
- Pre-filter: restrict candidates before the ANN search (more correct)
- Post-filter: search, then drop non-matches (may return too few)
Prefer pre-filtering when the DB supports it.
Where Vector Search Struggles
Vectors capture meaning but can miss exact terms — product codes, names, acronyms. A query for SKU-9F may semantically match nothing useful.
Hybrid search fixes this.
What Is Hybrid Search?
Hybrid search runs both keyword (e.g. BM25) and vector search, then merges the results. You get semantic understanding plus exact-term precision.
Combining Scores with RRF
Reciprocal Rank Fusion merges the two ranked lists by rewarding items ranked high in either, without needing comparable score scales.
def rrf(ranks, k=60):
return sum(1 / (k + r) for r in ranks)Tuning the Balance
Many databases let you weight keyword vs vector contributions (alpha). Term-heavy domains lean keyword; conceptual queries lean vector. Tune on your test set.
results = store.similarity_search(query, k=4, alpha=0.5)Operational Tips
For healthy vector search at scale:
- Rebuild or update indexes as data grows
- Keep embeddings and index dimensions consistent
- Benchmark recall and latency together
Quick Check
Test your vector database knowledge.
Recap
You learned to scale and sharpen vector search:
- ANN indexes like HNSW and IVF make search fast
- Metadata filters scope results; prefer pre-filtering
- Hybrid search blends keyword and vector retrieval
- Fuse rankings with RRF and tune the balance
- Maintain indexes and benchmark recall vs latency
These techniques keep retrieval both fast and accurate in production.
Frequently asked questions
Is the “Indexing, Filtering & Hybrid Search” lesson free?
Yes — the full text of “Indexing, Filtering & Hybrid Search” is free to read here on the web, and the LLM Apps in Production (RAG + Vector DB + Caching) course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the LLM Apps in Production (RAG + Vector DB + Caching) course, upgrade to CoddyKit PRO.
What will I learn in “Indexing, Filtering & Hybrid Search”?
Make vector search fast and precise at scale by understanding index types, combining metadata filters with similarity, and blending keyword and vector retrieval with hybrid search. You practise LLM Apps in Production (RAG + Vector DB + Caching) with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start LLM Apps in Production (RAG + Vector DB + Caching)?
No prior experience is required. LLM Apps in Production (RAG + Vector DB + Caching) on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Indexing, Filtering & Hybrid Search” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this LLM Apps in Production (RAG + Vector DB + Caching) lesson?
Yes. Every LLM Apps in Production (RAG + Vector DB + Caching) lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- The Necessity of Vector Databases
- Vector Embeddings and Similarity Search
- Integrating with a Vector Database
- Indexing, Filtering & Hybrid Search