Supported GQL Query Features

What works today, split by backend category. “Cypher backends” means Memgraph and Neo4j (translation is largely passthrough); “SQL backends” means PostgreSQL, MySQL and DuckDB.

ClickHouse, Apache Iceberg, and Apache Pinot are also supported as connectors but with a narrower verified surface. See each connector’s page for the exact list of features each one supports.

Known limitations

• Unbounded variable-length paths on SQL backends (()-[*]->()) return an actionable error.
• MATCH p = (...) path binding on quantified traversals (MATCH p = (a){1,3}(b) RETURN p) is not yet supported on SQL backends. Drop the path binding or run the query against a Cypher backend.
• Whole-node RETURN n over SQL backends projects scalar columns; the Bolt Node struct shape is reserved for Cypher backends today.

Graph Management Query Syntax

ADD GRAPH <name> ON CONNECTOR <connector>
    [GRAPH <remote_name>]
    [MAPPING <mapping_name>]
    [READ ONLY];

CREATE GRAPH <name>
    [{ <gql_schema_body> } | ANY]
    ON CONNECTOR <connector>;

UNADD GRAPH [IF EXISTS] <name>;
DROP GRAPH [IF EXISTS] <name>;

ALTER GRAPH <name> SET READ ONLY;
ALTER GRAPH <name> SET READ WRITE;
ALTER GRAPH <name> SET CONNECTOR <connector>;
ALTER GRAPH <name> SET GRAPH <remote_name>;
ALTER GRAPH <name> SET MAPPING <mapping_name>;
ALTER GRAPH <name> REMOVE MAPPING;

-- Single graph
USE <graph> <query>;

-- Composite
USE <graph1> <query>
UNION | UNION ALL | INTERSECT | INTERSECT ALL | EXCEPT | EXCEPT ALL
USE <graph2> <query>;

Configuration Reference

General

Logging

MemGQL writes log lines to the console (stdout/stderr) and, in parallel, to a log file. Both destinations are configured via CLI flags on the Bolt server binary.

CLI Flags

Log Levels

info is the most verbose level today. There is no debug or trace. The RUST_LOG environment variable is not consulted.

The log file always receives every log line — including queries, errors, and state changes — independent of the console --log-level. To silence the console while keeping a full file record, use --log-level=info-queries-only and tail the log file separately.

Enterprise License

When set, the license is decoded and verified against the organization name at startup. A valid enterprise license removes connector and connection limits. Without a license, community mode allows up to 2 connectors and 2 simultaneous connections.

Connector Types

Memgraph (memgraph, memgraph-gql)

Neo4j (neo4j, neo4j-gql)

PostgreSQL (postgres)

MySQL (mysql)

Oracle (oracle)

The Oracle connector uses 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 bundled Docker image ships only the bolt server binary plus TLS roots, and local builds work on macOS, Linux, and Windows without any extra system packages.

DuckDB (duckdb)

ClickHouse (clickhouse)

Apache Pinot (pinot)

Iceberg (iceberg)