seniorLLMs

How do you design scalable vector retrieval systems for LLMs?

Updated May 16, 2026

Short answer

Scalable vector retrieval systems use distributed indexing, ANN algorithms, and embedding optimization for efficient semantic search.

Deep explanation

RAG systems rely heavily on vector retrieval infrastructure. As datasets grow to billions of embeddings, exact nearest-neighbor search becomes computationally infeasible.

Scalable systems therefore use:

  1. Approximate Nearest Neighbor (ANN) algorithms.
  2. Distributed vector indices.
  3. Embedding compression.
  4. Hybrid retrieval combining semantic and keyword search.
  5. Sharding and replication.

Popular ANN algorithms include:

  • HNSW
  • IVF
  • PQ

The architecture balances recall quality, latency, and infrastructure cost.

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