docs/source/contributor-guide/development.md

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# Development

## Build prerequisites

- JDK 17 or newer.
- Rust toolchain (stable, installed via [rustup]).
- [`tpchgen-cli`] — only needed to generate test data for the Parquet
  integration test (`cargo install tpchgen-cli`).

Maven is bundled via the `./mvnw` wrapper; no separate Maven install is
required.

[rustup]: https://rustup.rs/
[`tpchgen-cli`]: https://github.com/clflushopt/tpchgen-rs

## Build and test

```sh
make test
```

This builds the native Rust crate and runs the JUnit tests. The steps can
be run individually:

```sh
cd native && cargo build
./mvnw test
```

The native library must be built before running JVM tests.

The first build in a fresh checkout reaches out to
`raw.githubusercontent.com` to fetch the DataFusion `.proto` files used
to generate the `datafusion-proto` Java classes. Subsequent builds are
offline; the `download-maven-plugin` cache under
`~/.m2/repository/.cache/` satisfies them.

## Test data

The Parquet integration test reads TPC-H SF1 data (~345 MB across 8 tables
in Snappy-compressed Parquet). Generate it once with:

```sh
make tpch-data
```

Tests that need this data skip cleanly if it is missing. `make clean`
does **not** remove `tpch-data/` — delete it manually to reclaim the
disk space.

## Repository layout

- `pom.xml` — Maven build descriptor.
- `Makefile` — top-level build orchestration (`make test`, `make tpch-data`).
- `mvnw`, `mvnw.cmd` — bundled Maven wrapper.
- `src/` — Java sources and tests.
- `native/` — Rust crate (JNI + Arrow C Data Interface).
- `docs/` — Sphinx documentation source and build scripts.