Phase 3: Enterprise RAG Systems · 55 min · Python · Pinecone · Qdrant

Vector Database Selection & Hybrid Search

Pure vector search fails in 87% of enterprise use cases. Hybrid is the baseline.

Hiring signal: System design interviews test vector DB selection rationale: candidates who choose Pinecone for managed simplicity, Qdrant for self-hosting, or pgvector for PostgreSQL integration — and can explain the trade-offs — pass. Candidates who default to 'whichever is popular' fail. Hybrid search with RRF is the expected 2026 baseline; pure vector search is a mark of inexperience.

What you will learn

Evaluate vector databases (Pinecone, Weaviate, Qdrant, pgvector, Milvus) against enterprise selection criteria
Implement hybrid search: BM25 (sparse) + dense vector retrieval with Reciprocal Rank Fusion
Tune RRF merge weights: 70% dense / 30% sparse as starting point, tuned on eval set
Implement query routing: classifying queries and routing to appropriate retrieval strategies

What You'll Learn

This lesson takes approximately 55 min. By the end, you will be able to:

Evaluate vector databases (Pinecone, Weaviate, Qdrant, pgvector, Milvus) against enterprise selection criteria
Implement hybrid search: BM25 (sparse) + dense vector retrieval with Reciprocal Rank Fusion
Tune RRF merge weights: 70% dense / 30% sparse as starting point, tuned on eval set
Implement query routing: classifying queries and routing to appropriate retrieval strategies

The Problem

Pure vector search — embedding similarity alone — fails in 87% of enterprise use cases. Enterprise queries often contain specific terms (product names, document IDs, dates) that vector embeddings don't capture well. Hybrid search, combining vector similarity with keyword/BM25 search, is the baseline for enterprise RAG.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers Vector Database Selection Criteria, Hybrid Search: BM25 + Dense Vectors with Reciprocal Rank Fusion, Query Routing, Practical Application, What Hiring Managers Look For, Resources, Key Takeaways, Next Steps — plus a hands-on lab, quiz, and project artifact.

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Key terms in this lesson

Hybrid Search