PostgreSQL

The PostgreSQL connector (CONNECTOR_TYPE=postgres) translates GQL queries into SQL and executes them against PostgreSQL. It requires a mapping file that maps graph patterns to relational tables.

1. Start PostgreSQL

docker network create memgql-net
 
docker run -d --rm \
    --name postgres-dev \
    --network memgql-net \
    -p 5432:5432 \
    --env POSTGRES_PASSWORD=postgres \
    postgres:18

2. Seed data

docker exec -i postgres-dev psql -U postgres << 'SQL'
CREATE TABLE IF NOT EXISTS persons (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    age INT
);
CREATE TABLE IF NOT EXISTS companies (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL
);
CREATE TABLE IF NOT EXISTS knows (
    from_id INT REFERENCES persons(id),
    to_id INT REFERENCES persons(id)
);
CREATE TABLE IF NOT EXISTS works_at (
    person_id INT REFERENCES persons(id),
    company_id INT REFERENCES companies(id)
);
 
INSERT INTO persons (id, name, age) VALUES (1, 'Alice', 30), (2, 'Bob', 25);
INSERT INTO companies (id, name) VALUES (1, 'Acme Corp');
INSERT INTO knows (from_id, to_id) VALUES (1, 2);
INSERT INTO works_at (person_id, company_id) VALUES (1, 1);
SQL

3. Start MemGQL

docker run --rm \
    --name memgql \
    --network memgql-net \
    --stop-timeout 2 \
    -p 7688:7688 \
    --env CONNECTOR_TYPE=postgres \
    --env POSTGRES_URL="host=postgres-dev user=postgres password=postgres dbname=postgres" \
    --env MAPPING_FILE=/data/mapping.json \
    --env BOLT_LISTEN_ADDR=0.0.0.0:7688 \
    -v ./mapping.json:/data/mapping.json \
    memgraph/memgql:latest

4. Connect

mgconsole --port 7688

5. Query

MATCH (p:Person) RETURN p.name, p.age;

MATCH (p:Person)-[:WORKS_AT]->(c:Company) RETURN p.name, c.name;

MATCH (a:Person)-[:KNOWS]->(b:Person) RETURN a.name, b.name;

For environment variables, see Configuration.

to Neo4j Configuration