Graph retrieval — research¶
Thirteen investigations — twelve external projects plus the in-house precedent — and the synthesis
that turns them into a gated build order for the links release and the graph release.
Research, not specification: where these disagree with ../DESIGN.md, DESIGN wins;
where they disagree with ../../plans/20260729_0256-links-and-graph.md about
what is built when, the plan wins.
Built, and its channel is off. The links release this research shaped shipped in 0.5.0 and
0.6.0, and the graph release completed in 0.11.0 — G1 and G4 in 0.6.0, G2 in 0.7.0, G3, G5 and G6 in
0.11.0. G5's gate ran and did not pass, so graph_channel ships off: the structure is built
and measured, and nothing in the staged channels below is licensed by that result.
../STATUS.md is the authority on what exists.
Start here¶
| Doc | What it is |
|---|---|
| PINAKES_APPROACH.md | The synthesis. The Pinakes graph: lazy, agent-driven, budget-tunable. §9 is the eval gate each channel must pass; §10 is its build order, sequenced into increments by plans/20260729_0256-links-and-graph.md. Five adversarial passes |
| GRAPH_RAG.md | The research record — what the literature actually says about graphs, RAG and agents, and what Pinakes should take from it |
Investigations¶
Licences are recorded because they decide whether an idea may become code here — see the gate below.
| Project | Licence | Why it was read |
|---|---|---|
| ClaudeKB | in-house | What was already tried here, and what it cost |
| LightRAG | MIT | Dual-level retrieval — the most-copied simple design |
| Microsoft GraphRAG | MIT | The reference implementation, and its own retreat from eager indexing into LazyGraphRAG |
| Graphiti | Apache-2.0 | Temporal knowledge graphs, bitemporal edges |
| HippoRAG 2 | MIT | Personalised PageRank over a passage graph — the PPR channel's origin |
| fast-graphrag | MIT | The cost profile of doing PPR cheaply |
| Graph-R1 | MIT | Agentic multi-turn traversal — closest to the agent-driven posture |
| datastax/graph-rag | Apache-2.0 | Retrofitting edges onto an existing vector store |
| code-graph-rag | MIT | Structural edges that need no LLM |
| MiniRAG | MIT | Whether a small local model suffices for heterogeneous graph indexing |
| LinearRAG | ⛔ GPL-3.0 | Linear-cost construction — whether the build step can stay free |
| LogicRAG | ⛔ GPL-3.0 | Reasoning over logical structure — the upper bound on query complexity |
| Youtu-GraphRAG | ⛔ academic only | Schema-guided hierarchical construction — schema as a cost control |
The licence gate¶
These are read-only references. Never copy code from the three marked ⛔.
- LinearRAG and LogicRAG are GPL-3.0.
- Youtu-GraphRAG ships a custom licence forbidding commercial and production use. Its README
badge says MIT and is wrong — the
LICENSEfile is the truth.
Pinakes is Apache-2.0 and pnk serve is a network service, so a copyleft obligation would reach
anyone embedding it. The same reasoning ruled out PyMuPDF in favour of pypdfium2
(plans/20260727_1543-v0.2.md, decision 1). Ideas and measured results are free to reuse; source is not —
read them, then write it yourself. Stated once in
PINAKES_APPROACH.md §"License gate" and repeated here because the index is
where someone starts.