ModelRefs / Document Summary Index — AI Glossary
Document Summary Index — AI Glossary
A RAG index storing LLM-generated summaries per document alongside full chunks, enabling summary-level retrieval followed by chunk-level reading.
Overview
LlamaIndex's DocumentSummaryIndex generates a summary per document at index time. At query time, the summary index is searched first to identify relevant documents; full chunks of those documents are then used for generation. Improves performance on global questions requiring understanding of entire documents, outperforming flat chunk retrieval.
Reference details
| Topic | rag |
|---|---|
| Last reviewed | 2026-06-24 |
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Frequently asked questions
What is Document Summary Index?
A RAG index storing LLM-generated summaries per document alongside full chunks, enabling summary-level retrieval followed by chunk-level reading.
What concepts are related to Document Summary Index?
Closely related concepts include raptor, parent document retrieval, advanced rag.