pg-graph

Graph database skills for Apache AGE on PostgreSQL. Covers the full lifecycle: deriving an ontology from structured or unstructured data with a human feedback loop, building the graph, and querying it with openCypher, natural language to Cypher, and graph augmented retrieval.

pg-graph — Apache AGE Graph Skills (Routing Table)

Use references as supplemental context, combined with your Apache AGE and openCypher knowledge. If reference guidance is incomplete, answer with appropriate caveats rather than inventing syntax.

This skill is the single home for graph work on PostgreSQL, covering the full lifecycle. The generic PostgreSQL skill (postgresql-best-practices) points here for anything involving Apache AGE, openCypher, ag_catalog, knowledge graphs, or ontology. Keep AGE specific guidance in this skill rather than duplicating it in the generic skill.

Lifecycle: construct then consume

Derive an ontology from the user's structured or unstructured data, and run a human feedback loop before finalizing. See ontology-derivation.
Build the graph by extracting, deduplicating, and MERGE loading into AGE using the finalized ontology. See extract-to-graph.
Consume the graph with openCypher, natural language to Cypher, schema introspection, and graph augmented retrieval.

Construction uses only capabilities available today: agent driven extraction over the MCP query tools (works on any PostgreSQL with AGE), or the azure_ai extension for in-database work at scale on Azure. It does NOT depend on unreleased ai.* pipeline primitives. Never finalize an ontology without explicit user approval.

Prerequisites (verify before graph work)

Apache AGE is an extension. Confirm it is installed and load it once per session before any Cypher call.
On managed Azure Database for PostgreSQL (Flexible Server and Azure HorizonDB), age must be allowlisted in azure.extensions and added to shared_preload_libraries, then created with CREATE EXTENSION IF NOT EXISTS age CASCADE;. Set both on Flexible Server via server parameters; on Azure HorizonDB via a parameter group connected to the cluster. Both auto-restart to apply. It cannot be enabled with ALTER SYSTEM. AGE is preloaded on both, so do NOT run LOAD 'age'; there (a non-superuser gets access to library "age" is not allowed).
Non superuser sessions must set search_path so ag_catalog is available but NOT first. Use SET search_path = public, ag_catalog;. Putting ag_catalog first makes ordinary CREATE TABLE fail with permission denied for schema ag_catalog.

Key Constraints (what models get wrong)

Fact	Detail
Cypher is wrapped in a function	Every query runs as `SELECT * FROM ag_catalog.cypher('graph_name', $$ ... $$) AS (col agtype)`. It is not a bare statement.
Column definition list is required	The `AS (col agtype)` list must match the RETURN arity, and every returned column is typed `agtype`.
agtype casting	Scalars come back as `agtype`. Cast for SQL use rather than assuming a raw text or int is returned. State uncertainty about exact cast helpers instead of inventing function names.
search_path ordering	`SET search_path = public, ag_catalog;` (never `ag_catalog` first) for non superuser roles.
Graph must exist	Create the graph once with `create_graph('graph_name')` before MERGE or MATCH.
MERGE for idempotent load	Use `MERGE` on a stable business key to avoid duplicate vertices during repeated extraction.
Parameters	AGE Cypher does not accept host bind parameters inside `$$...$$` the way SQL does. Interpolate safely on the server side or wrap the cypher call in SQL. Never string concatenate untrusted input.

Routing Table

Keyword triggers	Reference	When to use
derive ontology, suggest ontology, generate ontology, ontology from data, ontology from documents, propose ontology	ontology-derivation	Analyze structured or unstructured data, propose an ontology, and run a human feedback loop before finalizing
extract to graph, build graph from data, build knowledge graph, populate graph, extract entities to graph	extract-to-graph	Apply a finalized ontology: extract, deduplicate, and MERGE into the AGE graph
entity resolution, context dedup, deduplicate entities, canonicalize entities, merge duplicate entities	context-dedup	Resolve entity aliases using type, graph neighborhood, and source snippet, with scalable blocking and a persistent canonical map
apache age, opencypher, cypher(), create_graph, property graph, vertices and edges, MERGE node	opencypher-age-patterns	AGE setup, Cypher wrapping, MATCH/MERGE/CREATE patterns, indexing vertices and edges
text to cypher, natural language to cypher, english to cypher, generate cypher, nl to cypher	text-to-cypher	Turning a user question into a validated openCypher query and running it
graph schema, list vertex labels, edge labels, ag_label, describe graph	graph-schema-introspection	Discovering labels, edge types, and properties so generated Cypher is grounded
visualize graph, vs code graph, render the graph, graph explorer, see the graph, plot the graph, ms-ossdata.vscode-pgsql	text-to-cypher	Generate visualization-ready Cypher (full vertex/edge objects, `disp_label`, matched `AS` columns) for the PostgreSQL extension for VS Code graph explorer
graph rag, graph augmented, graph augmented retrieval, hybrid graph retrieval	graph-augmented-rag	Retrieval that combines vector similarity with graph traversal and reranking
explainability, traceability, provenance, why this recommendation, reasoning path, audit graph answer	graph-explainability	Make facts traceable to sources and recommendations explainable: provenance on vertices and edges, returned reasoning path, weakest link path confidence, and a reproducible reasoning trace log
graph semantic search, graph azure_ai embeddings, graph azure openai embeddings, enable azure_ai for graph, configure azure openai for graph	azure-ai-semantic-search	Enable and configure the `azure_ai` extension, prompt the user for endpoint/key/deployment, and generate embeddings for semantic search
cypher example, graph query example, worked graph example	examples	End to end worked examples spanning schema, query, and results

Anti-Hallucination Rules

Do NOT present a Cypher query as a bare statement. Always wrap it in ag_catalog.cypher(...) with a column definition list.
Do NOT claim host bind parameters work inside the $$...$$ body.
Do NOT put ag_catalog first in search_path.
Do NOT enable age with ALTER SYSTEM on managed Azure. Use the azure.extensions + shared_preload_libraries allowlist, set via server parameters (Flexible Server) or a parameter group connected to the cluster (Azure HorizonDB).
Verify labels and properties with schema introspection before generating Cypher against an unknown graph.
State uncertainty about exact agtype cast helpers rather than inventing function names.
Do NOT finalize a derived ontology without explicit user approval. Treat it as a proposal and run the feedback loop.
Do NOT rely on unreleased ai.* pipeline primitives. Use agent-driven extraction or the azure_ai extension over Apache AGE, both available today.
For semantic search, do NOT invent an Azure OpenAI endpoint, key, or embedding deployment name. Read current azure_ai settings and ask the user for anything missing. See azure-ai-semantic-search.
Do NOT present a graph recommendation without its reasoning path, supporting evidence, and a confidence bounded by the weakest edge on the path. See graph-explainability.