Oracle

The Oracle connector (CONNECTOR_TYPE=oracle) translates GQL queries into Oracle-dialect SQL and executes them against Oracle Database 19c+, including Oracle Database Free 23ai. It requires a mapping file that maps graph patterns to relational tables.

The driver is oracle-rs, a pure-Rust implementation of Oracle’s TNS wire protocol, pooled via deadpool-oracle. No OCI / ODPI-C / Instant Client is required at build or runtime — the memgraph/memgql:latest Docker image ships only the bolt server binary plus TLS roots, and cargo run works on macOS, Linux, and Windows without any extra system packages.

1. Start Oracle Database Free 23ai

docker network create memgql-net
 
docker run -d --rm \
    --name oracle-dev \
    --network memgql-net \
    -p 1521:1521 \
    --env ORACLE_PASSWORD=oracle \
    --env APP_USER=app \
    --env APP_USER_PASSWORD=oracle \
    gvenzl/oracle-free:23-slim-faststart

The first start downloads the image and bootstraps the PDB (FREEPDB1); this takes ~2-3 minutes. Subsequent starts are near-instant. Watch readiness with:

docker logs -f oracle-dev   # wait for: DATABASE IS READY TO USE!

2. Seed data

docker exec -i oracle-dev bash -lc \
    "sqlplus -L -S system/oracle@//localhost:1521/FREEPDB1" << 'SQL'
WHENEVER SQLERROR EXIT FAILURE
SET ECHO OFF FEEDBACK OFF HEADING OFF
 
CREATE TABLE persons (
    id   NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    name VARCHAR2(255) NOT NULL,
    age  NUMBER
);
 
CREATE TABLE companies (
    id   NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    name VARCHAR2(255) NOT NULL
);
 
CREATE TABLE knows (
    id      NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    from_id NUMBER NOT NULL REFERENCES persons(id),
    to_id   NUMBER NOT NULL REFERENCES persons(id)
);
 
CREATE TABLE works_at (
    id         NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    person_id  NUMBER NOT NULL REFERENCES persons(id),
    company_id NUMBER NOT NULL REFERENCES companies(id)
);
 
INSERT INTO persons (name, age) VALUES ('Alice', 30);
INSERT INTO persons (name, age) VALUES ('Bob',   25);
INSERT INTO companies (name)     VALUES ('Acme Corp');
INSERT INTO knows (from_id, to_id) VALUES (1, 2);
INSERT INTO works_at (person_id, company_id) VALUES (1, 1);
COMMIT;
EXIT
SQL

3. Start MemGQL

docker run --rm \
    --name memgql \
    --network memgql-net \
    --stop-timeout 2 \
    -p 7688:7688 \
    --env CONNECTOR_TYPE=oracle \
    --env ORACLE_URL="oracle://system:oracle@oracle-dev:1521/FREEPDB1" \
    --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;

Dialect notes

Positional bind variables use Oracle’s native :1, :2, … form.
LIMIT n OFFSET m is rendered as the SQL-standard OFFSET m ROWS FETCH NEXT n ROWS ONLY (Oracle 12c+).
Aliased single-table DELETE is DELETE FROM table alias WHERE alias.col … — Oracle accepts table aliases but does not allow the AS keyword in this position.
No INSERT … RETURNING *. Oracle supports RETURNING <cols> INTO :out, but this is bind-variable based and the planner stays bind-agnostic; the executor uses it only when the caller needs the auto-generated key.
Identifiers from the mapping file are emitted unquoted, so Oracle’s default UPPERCASE folding applies — match your mapping table / id_column spellings to your physical schema accordingly.

Multi-connection mode

Inside CONNECTOR_TYPE=multi, register Oracle the same way as any other backend:

ADD MAPPING social FROM '/data/mapping.json';
ADD CONNECTOR ora TYPE oracle URI 'oracle://system:oracle@oracle-dev:1521/FREEPDB1' MAPPING social;
CONNECT ora AS ora_conn;
USE CONNECTION ora_conn MATCH (n:Person) RETURN n.name LIMIT 5;

For environment variables, see Reference.

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