ModelRefs / Parent Document Retrieval — AI Glossary
Parent Document Retrieval — AI Glossary
Indexing small child chunks for precise retrieval but returning the larger parent document to the LLM for richer context.
Overview
Parent document retrieval (LangChain ParentDocumentRetriever) indexes small, fine-grained chunks for high semantic precision in retrieval, then fetches the full parent chunk or document before generation. Balances retrieval precision (small chunks) with generation context richness (large chunks). Reduces the tradeoff between chunk size and quality.
Reference details
| Topic | rag |
|---|---|
| Last reviewed | 2026-06-24 |
Related terms
Commonly confused with
Both this and sentence-window retrieval index something small and return something larger, to get precise matching with usable context. They differ in what the larger unit is: here it is a pre-existing parent — a section or whole document — so it needs a document hierarchy to exist, and returns a unit an author defined. Sentence-window computes its span around the hit instead.
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Frequently asked questions
What is Parent Document Retrieval?
Indexing small child chunks for precise retrieval but returning the larger parent document to the LLM for richer context.
What concepts are related to Parent Document Retrieval?
Closely related concepts include sentence window retrieval, chunk overlap, text splitter.