The global context index is an optional summary layer that helps Cognee answer questions that depend on the broader shape of a dataset, not only the closest graph facts. Normal graph retrieval is local: Cognee searches for graph edges, chunks, summaries, and entities that match the query. That works well when the answer is near a few specific facts. The global context index adds a higher-level map: semantic buckets ofDocumentation Index
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TextSummary nodes and a root summary of the dataset.
Why use it
Use the global context index when answers often depend on document-wide or dataset-wide context:- long documents where important details are spread across chapters or sections
- evolving conversations where the final state depends on earlier updates
- project memory where the answer needs the overall plan, risks, and current status
- policy or research corpora where local facts need broader framing
- local evidence from the graph
- global orientation from compact dataset summaries
How it works
During normal ingestion and enrichment, Cognee createsDocumentChunk and TextSummary datapoints. The global context index adds the GlobalContextSummary layers shown inside the dashed lines:
TextSummary nodes. The retrieval hierarchy is top-down, starting from the root summary.
The index groups
TextSummary nodes, not raw DocumentChunk nodes directly.What retrieval adds
When enabled for graph completion search, Cognee prepends a global context prelude before the usual graph context:GlobalContextSummary. The Relevant areas are the top matching non-root GlobalContextSummary bucket texts for the query.
This gives the model a compact map before it reads the local graph facts.
Build the index
The index is opt-in. Build it after memory has been created:improve() first runs the normal enrichment pass, then builds the global context index.
Use it during search
Enable it throughretriever_specific_config on graph completion search:
only_context=True:
Configuration
| Option | Default | Where it is used | What it does |
|---|---|---|---|
build_global_context_index | False | cognee.improve() | Builds the bucket and root summaries after enrichment. |
include_global_context_index | False | retriever_specific_config | Prepends global context during GRAPH_COMPLETION retrieval. |
global_context_index_top_k | 3 | retriever_specific_config | Number of non-root bucket summaries to include as relevant areas. |
Benefits and tradeoffs
The main benefit is better long-range coherence. The model can see a compact summary of the dataset before it reasons over the retrieved graph context. This can reduce failures where local retrieval finds a relevant fragment but misses the broader story. The tradeoff is that the index is lossy. A bucket summary is an orientation aid, not a replacement for source chunks or graph facts. The most reliable answers still come from combining global context with precise retrieved evidence. Building the index also adds work: Cognee clusters summaries and calls the LLM to summarize buckets and the root.When not to use it
You may not need the global context index when:- your dataset is small enough that normal retrieval already has enough context
- queries are mostly simple fact lookups
- you need the fastest possible enrichment pass
- you want retrieval context to contain only direct local graph evidence