AI engineering glossary · RAG vector search
What is retriever?
Retriever: The component of a RAG system that takes a query and returns the most relevant pieces of a knowledge base. It may use vector similarity, keyword matching or both. Its quality sets a ceiling on the final answer, because the generator cannot use a passage that was never fetched.
Retriever: an example
A retriever receives 'refund rules for cancelled flights' and returns the 5 highest-scoring paragraphs from an airline's help pages.
Related terms
More RAG vector search terms
- Scalar quantisation
- Score fusion
- Self-RAG
- Semantic cache
- Semantic chunking
- Sentence window retrieval
- Similarity threshold
- Small-to-big retrieval
Where you learn it
Retriever is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.