Architecture

GraphRAG SDK v2 follows a strategy-based pipeline architecture. Every algorithmic concern is an abstract base class (ABC) with swappable implementations. The system has two main flows: ingestion (document to knowledge graph) and retrieval (question to answer).

Design Principles

Strategy Modularity — Every pipeline step is an ABC. Swap any implementation without touching other code.
Zero-Loss Data — Full provenance chain from raw text to graph nodes (Document -> Chunk -> Entity).
Production Latency — Async-first, connection pooling, batched writes, parallel pipeline steps.
Simplicity — Single entry point (GraphRAG), flat package structure, no meta-programming.

Ingestion Pipeline

The ingestion pipeline transforms documents into a knowledge graph in 9 steps. Steps 1-7 run sequentially (each depends on the previous), steps 8-9 run in parallel.

                    Sequential                              Parallel
  ┌──────────────────────────────────────────┐    ┌──────────────────────┐
  │ 1.Load  2.Chunk  3.Lexical  4.Extract    │    │ 8. Mentions          │
  │ 5.Prune  6.Resolve  7.Write             │──>│ 9. Index Chunks      │
  └──────────────────────────────────────────┘    └──────────────────────┘

Step-by-Step

Step	Name	What it does	Strategy ABC
1	Load	Reads raw text from a source (file, URL, raw string)	`LoaderStrategy`
2	Chunk	Splits text into overlapping windows	`ChunkingStrategy`
3	Lexical Graph	Creates Document and Chunk nodes with PART_OF and NEXT_CHUNK edges (provenance chain)	Built-in
4	Extract	LLM extracts entities, relationships, and mentions from each chunk	`ExtractionStrategy`
5	Prune	Filters extracted data against the schema (removes off-schema entities/relationships)	Built-in
6	Resolve	Deduplicates entities (exact match or LLM-assisted description merge)	`ResolutionStrategy`
7	Write	Batched MERGE of nodes and relationships into FalkorDB	Built-in
8	Mentions	Writes MENTIONED_IN edges linking entities to their source chunks	Built-in (parallel)
9	Index Chunks	Embeds chunk text and stores vector embeddings on Chunk nodes	Built-in (parallel)

Data Flow

str (raw text)
  -> DocumentOutput (text + metadata)
    -> TextChunks (list of TextChunk with uid, text, index)
      -> GraphData (nodes + relationships extracted by LLM)
        -> ResolutionResult (deduplicated nodes + remapped relationships)
          -> FalkorDB (MERGE via GraphStore + vector index via VectorStore)

Graph Schema

The knowledge graph contains these node types and edge types:

Node Labels

Label	Purpose	Has Embedding
`Document`	Source document metadata	No
`Chunk`	Text chunk (fragment of a document)	Yes
`__Entity__`	Secondary label on all extracted entities	Yes (after backfill)
`Person`, `Organization`, etc.	Primary entity labels — 11 defaults: Person, Organization, Technology, Product, Location, Date, Event, Concept, Law, Dataset, Method	Via `__Entity__`

Edge Types

Type	Source -> Target	Purpose
`PART_OF`	Document -> Chunk	Provenance: which document a chunk came from
`NEXT_CHUNK`	Chunk -> Chunk	Sequential ordering of chunks
`MENTIONED_IN`	Entity -> Chunk	Which chunks mention an entity
`RELATES`	Entity -> Entity	All extracted relationships (single edge type)

All LLM-extracted relationships use the single RELATES edge type. The original relationship type (e.g. WORKS_AT, LOCATED_IN) is preserved as the rel_type property on the edge. A fact property stores a human-readable fact string for embedding.

Post-ingestion: Entity Deduplication

Entity deduplication is handled post-ingestion via deduplicate_entities() rather than during the pipeline. This allows ingesting multiple documents independently, then deduplicating globally. The method groups entities by (normalized name, label) to prevent cross-type merging (e.g. Person “Paris” and Location “Paris” remain separate).

Retrieval Flow

The retrieval system answers questions by searching the knowledge graph through multiple paths, then generating an answer with the LLM.

Question
  |
  v
Keyword Extraction (LLM)
  |
  v
Embed Question (single API call)
  |
  ├── RELATES Edge Vector Search ────────────────────────────┐
  │   -> fact strings + entity entry points                  │
  │                                                          │
  ├── 2-Path Entity Discovery ──────────────────────────────┤
  │   1. Cypher CONTAINS substring match                     │
  │   2. Fulltext search on entity index                     │
  │   + merge entities from RELATES vector search            │
  │                                                          v
  │                                              Top entities (scored + deduped)
  │                                                         |
  │                                              2-Hop Relationship Expansion
  │                                              (1-hop + 2-hop from top entities)
  │                                                         |
  ├── 4-Path Chunk Retrieval ───────────────────────────────┤
  │   1. Fulltext search in chunks                           │
  │   2. Vector search in chunks                             │
  │   3. MENTIONED_IN traversal (entity -> chunk)            │
  │   4. 2-hop: entity -> neighbor -> chunk                  │
  │                                                          v
  │                                              Candidate chunks (cosine reranked)
  │                                                         |
  └──────────────────────────────> Context Assembly
                                    (hint, entities, relationships, facts, passages)
                                          |
                                          v
                                    LLM Generation (RAG prompt)
                                          |
                                          v
                                       Answer

MultiPathRetrieval Parameters

Parameter	Default	Purpose
`chunk_top_k`	15	Final chunks after reranking
`max_entities`	30	Total entity cap across all paths
`max_relationships`	20	Max relationships in context
`rel_top_k`	15	RELATES edge vector search results
`keyword_limit`	10	Max keywords extracted from question

Storage Layer

GraphStore

All graph writes go through GraphStore, which provides:

Batched UNWIND upserts — 500 nodes/relationships per batch
Label hints — relationship MATCH queries use label hints (e.g., MENTIONED_IN matches __Entity__ -> Chunk) for faster lookups
Per-item fallback — if a batch fails, retries individual items
None-id guard — filters out entities with None/empty IDs (bad LLM extraction)

VectorStore

Vector operations go through VectorStore:

Index creation — CREATE VECTOR INDEX for Chunk and Entity embeddings, plus RELATES edge embeddings
Fulltext index — for keyword search on chunk text and entity names
Batched embedding — embeds texts in bulk, stores via UNWIND
Search — db.idx.vector.queryNodes for similarity search

Extending the SDK

To add a custom strategy, subclass the relevant ABC:

from graphrag_sdk import ChunkingStrategy, TextChunks
from graphrag_sdk.core.context import Context

class SemanticChunking(ChunkingStrategy):
    async def chunk(self, text: str, ctx: Context) -> TextChunks:
        # Your implementation here
        ...

Then pass it to ingest():

await rag.ingest("doc.txt", chunker=SemanticChunking())

The same pattern applies to all 6 strategy ABCs: LoaderStrategy, ChunkingStrategy, ExtractionStrategy, ResolutionStrategy, RetrievalStrategy, RerankingStrategy.

Deep Dives

Each subsystem has a dedicated document with step-by-step explanations:

Ingestion Pipeline — the 9-step pipeline from document to knowledge graph
Extraction — the 2-step hybrid extraction process (NER + LLM)
Graph Schema — how the knowledge graph is structured in FalkorDB
Storage — GraphStore, VectorStore, and EntityDeduplicator internals
Retrieval — the multi-path retrieval system that answers questions

Home

Pipeline

Ontology

Reference

Design Principles

Ingestion Pipeline

Step-by-Step

Data Flow

Graph Schema

Node Labels

Edge Types

Post-ingestion: Entity Deduplication

Retrieval Flow

MultiPathRetrieval Parameters

Storage Layer

GraphStore

VectorStore

Extending the SDK

Deep Dives

​Design Principles

​Ingestion Pipeline

​Step-by-Step

​Data Flow

​Graph Schema

​Node Labels

​Edge Types

​Post-ingestion: Entity Deduplication

​Retrieval Flow

​MultiPathRetrieval Parameters

​Storage Layer

​GraphStore

​VectorStore

​Extending the SDK

​Deep Dives

Design Principles

Ingestion Pipeline

Step-by-Step

Data Flow

Graph Schema

Node Labels

Edge Types

Post-ingestion: Entity Deduplication

Retrieval Flow

MultiPathRetrieval Parameters

Storage Layer

GraphStore

VectorStore

Extending the SDK

Deep Dives