graph

pggraph : Graph database capabilities for PostgreSQL

Overview

Packages

Source

pig build pkg pggraph;		# build rpm/deb

Install

Make sure PGDG and PIGSTY repo available:

pig repo add pgsql -u   # add both repo and update cache

Install this extension with pig:

pig install pggraph;		# install via package name, for the active PG version
pig install graph;		# install by extension name, for the current active PG version

pig install graph -v 18;   # install for PG 18
pig install graph -v 17;   # install for PG 17
pig install graph -v 16;   # install for PG 16
pig install graph -v 15;   # install for PG 15
pig install graph -v 14;   # install for PG 14

Create this extension with:

CREATE EXTENSION graph;

Usage

Sources:

• pgGraph v0.1.8 README
• v0.1.8 release notes
• SQL API Reference
• Schema Registration
• Administration and Security

pggraph is the package and PGXN distribution name, but the installed PostgreSQL extension is graph. The extension builds derived graph artifacts from ordinary PostgreSQL tables, keeps those tables as the source of truth, and exposes graph search, traversal, shortest path, GQL-style reads, and selected mapped writes through the graph schema.

v0.1.8 adds named graph administration, graph-scoped catalogs, graph grants and quotas, hosted maintenance jobs, relationship creation in GQL, and explicit compatibility boundaries for openCypher and SQL/PGQ preview behavior. Upstream still labels pgGraph as early alpha; test it in a disposable or development database first, and rebuild graph artifacts from source tables rather than treating them as authoritative storage.

Basic Graph Build

CREATE EXTENSION IF NOT EXISTS graph;
SELECT graph.reset();

CREATE TABLE companies (
  id   text PRIMARY KEY,
  name text NOT NULL
);

CREATE TABLE people (
  id         text PRIMARY KEY,
  name       text NOT NULL,
  company_id text REFERENCES companies(id)
);

INSERT INTO companies VALUES
  ('c1', 'Acme Bank'),
  ('c2', 'Northwind Trading');

INSERT INTO people VALUES
  ('p1', 'Alice', 'c1'),
  ('p2', 'Bob', 'c1'),
  ('p3', 'Carol', 'c2');

SELECT * FROM graph.auto_discover('public');
SELECT * FROM graph.build();

SELECT node_count, edge_count, edge_types
FROM graph.status();

graph.auto_discover('public') scans primary keys and foreign keys in the selected schema, registers discovered source tables and edges, and prepares the graph for graph.build(). In production schemas, prefer explicit registration so labels, search columns, filter columns, weights, tenant behavior, and graph identity are deliberate.

Manual and Named-Graph Registration

SELECT graph.create_graph('customer_360', namespace := 'analytics');
SELECT graph.set_current_graph('customer_360', namespace := 'analytics');

SELECT graph.add_table(
  table_name := 'public.people'::regclass,
  id_column  := 'id',
  columns    := ARRAY['name'],
  tenant_column := NULL
);

SELECT graph.add_table_to_graph(
  graph_name := 'customer_360',
  table_name := 'public.companies'::regclass,
  id_column  := 'id',
  columns    := ARRAY['name'],
  graph_namespace := 'analytics'
);

SELECT graph.add_edge_to_graph(
  graph_name := 'customer_360',
  from_table := 'public.people'::regclass,
  from_column := 'company_id',
  to_table := 'public.companies'::regclass,
  to_column := 'id',
  label := 'works_at',
  bidirectional := true,
  graph_namespace := 'analytics'
);

SELECT * FROM graph.build_graph('customer_360', graph_namespace := 'analytics');

Registration applies to the current graph selection unless you use the explicit *_to_graph and *_from_graph helpers. Node identifiers must match a primary key or a unique NOT NULL index. columns controls searchable and GQL-visible properties; traversal filter pushdown uses separate graph.add_filter_column() registrations. Edge-table and junction-table relationships are also supported, and label_column can provide dynamic edge labels up to the v0.1.8 user-facing label limit.

Search, Traversal, and Paths

SELECT node_table_name, node_id, node
FROM graph.search(
  property_key   := 'name',
  property_value := 'Alice',
  table_filter   := 'public.people'::regclass,
  mode           := 'exact',
  hydrate        := true
);

SELECT depth, node_table_name, node_id, edge_path
FROM graph.traverse(
  'public.people'::regclass,
  'p1',
  2,
  hydrate := false
);

SELECT step, node_table_name, node_id, edge_label
FROM graph.shortest_path(
  'public.people'::regclass,
  'p1',
  'public.companies'::regclass,
  'c1',
  hydrate := false
);

With hydrate := false, graph functions return compact graph coordinates. With hydration enabled, PostgreSQL source-table ACLs and RLS still govern which source rows are visible. Stale coordinates fail closed rather than fabricating rows.

GQL Queries and Relationship Writes

SELECT row
FROM graph.gql(
  'MATCH (p:people)-[:works_at]->(c:companies)
   WHERE p.name = $name
   RETURN p.id AS person_id, c.name AS company
   ORDER BY company',
  params  := '{"name":"Alice"}'::jsonb,
  hydrate := true
);

graph.gql() returns one jsonb object per SQL row. Node labels map to registered table names and relationship types map to registered edge labels. v0.1.8 extends the mutable GQL surface with registered relationship creation: mapped writes still go through PostgreSQL source-table DML, and source tables remain authoritative. Unsupported openCypher or SQL/PGQ shapes now fail with clearer capability errors instead of partial behavior.

Administration and Operations

GRANT USAGE, CREATE ON SCHEMA graph TO graph_admin;

SELECT * FROM graph.grant_graph('customer_360', 'app_reader', 'read', namespace := 'analytics');
SELECT * FROM graph.set_graph_quota('owner', 'max_named_graphs', 25, scope_key := 'app_owner');
SELECT * FROM graph.select_graph('customer_360', namespace := 'analytics');
SELECT * FROM graph.add_sync_policy('customer_360', schedule_interval_secs := 300, graph_namespace := 'analytics');
SELECT * FROM graph.run_due_jobs();
SELECT * FROM graph.projection_status();

Graph administration covers catalog mutation, builds, sync replay, maintenance, quotas, runtime graph loading, and global analytics. Named graph privileges are read, write, build, and admin, but graph read is not enough by itself: hydrated reads still require SELECT on source tables. A selected graph tenant also scopes traversal, search, GQL, and Cypher calls unless an explicit matching tenant is supplied.

Caveats

• Source tables remain the source of truth. Graph artifacts, projection files, sync state, and runtime engines are derived and rebuildable.
• Use graph.build() or graph-scoped build helpers after registration changes, and use sync/maintenance APIs when relying on incremental projection state.
• Internal catalog tables such as graph._graphs, grants, quotas, jobs, sync logs, and projection metadata are implementation details; use public SQL functions instead.
• v0.1.8 raises the source-build baseline to Rust 1.96 and cargo-pgrx 0.19.1. PostgreSQL 14 through 18 remain supported upstream, with PostgreSQL 17 as the default release-gate target.