How to create a query module in Rust

To create a query module in Rust for Memgraph, you need to compile your code into a shared library (.so file) that Memgraph can load dynamically at runtime.

Development environment options

You have two main ways to set up your Rust development environment:

1. Using your own environment
   You can compile Rust query modules on your local machine or server, but you’ll need to manually install Rust tooling and any necessary dependencies (like cargo and system libraries).

2. Using the MAGE environment
   The Memgraph MAGE development Docker image (with the -dev tag) contains all required dependencies and provides an isolated environment ideal for development.

See the quickstart to custom query module in Rust for a full guide.

How the Rust API works

The Rust API is a wrapper around Memgraph’s C API, providing a more ergonomic and memory-safe interface while maintaining high performance. Query modules written in Rust are compiled to shared libraries and loaded by Memgraph at startup.

• The API includes wrappers for working with graph data, procedures, results, errors, and more.
• You can define custom procedures using macros like init_module!, define_procedure!, and close_module!.
• Exception handling in Rust (with Result types) ensures better stability, but unhandled panic! calls can still crash Memgraph.

Full reference: Rust API documentation.

Quickstart summary

To get started quickly:

1. Run Memgraph using the MAGE development Docker image.
2. Install cargo inside the container.
3. Copy the query module boilerplate and adjust Cargo.toml and lib.rs.
4. Build your module using python3 setup build -p /usr/lib/memgraph/query_modules/.
5. Load the module in Memgraph with CALL mg.load_all();.

Follow the quickstart guide for detailed instructions.