AI engineering glossary · RAG vector search
What is vector index?
Vector index: The data structure that organises stored vectors so nearest-neighbour queries need not compare against every vector. Common types include graph-based, cluster-based and hashing-based indexes, each trading speed, memory and accuracy differently.
Vector index: an example
Building an HNSW index over 2 million vectors lets a query touch only a few thousand of them.
Related terms
More RAG vector search terms
- Vector normalisation
- Vector quantisation
- Abstention
- Access control in retrieval
- Agentic RAG
- Alpha weighting
- ANN recall
- Answer correctness
Where you learn it
Vector index is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.