feat: add GEMINI.md for Gemini Code Assistant workspace context and setup instructions

Author: kosiew

GEMINI.md

@@ -0,0 +1,96 @@
+# Gemini Code Assistant Workspace Context
+
+This document provides context for the Gemini Code Assistant to understand the `datafusion-python` repository.
+
+## Project Overview
+
+This repository contains the source code for the Python bindings for Apache Arrow DataFusion, an in-memory query engine. It allows users to execute SQL queries and use a DataFrame API against various data sources such as Parquet, CSV, and JSON. The library also supports interoperability with other Python data ecosystem libraries like Pandas and PyArrow.
+
+## Key Technologies and Libraries
+
+- **Primary Language:** Rust (for the core bindings)
+- **Python Interface:** Python
+- **Core Engine:** [Apache Arrow DataFusion](https://github.com/apache/datafusion)
+- **Python Bindings Framework:** [PyO3](https://pyo3.rs/)
+- **Build and Packaging:** [maturin](https://www.maturin.rs/)
+- **Dependency Management:** [uv](https://github.com/astral-sh/uv) and pip
+- **Testing:** [pytest](https://docs.pytest.org/)
+- **Linting:** [ruff](https://github.com/astral-sh/ruff) for Python, `rustfmt` and `clippy` for Rust
+- **CI/CD:** GitHub Actions
+
+## Repository Structure
+
+The repository is organized as follows:
+
+- `src/`: Contains the Rust source code for the Python bindings.
+- `python/`: Contains the Python-specific code and tests.
+- `examples/`: Contains example usage scripts.
+- `dev/`: Contains development scripts, including those for releases and changelogs.
+- `ci/`: Contains scripts for continuous integration checks.
+- `docs/`: Contains the documentation for the project.
+- `pyproject.toml`: Defines the Python project metadata and dependencies.
+- `Cargo.toml`: Defines the Rust project metadata and dependencies.
+
+## How to Build and Test
+
+### Development Setup
+
+1.  **Prerequisites:**
+    *   Rust and Cargo
+    *   Python 3
+    *   `uv` (recommended) or `pip`
+
+2.  **Clone the repository and set up the environment:**
+
+    ```bash
+    git clone git@github.com:apache/datafusion-python.git
+    cd datafusion-python
+    ```
+
+3.  **Initialize git submodules:**
+
+    ```bash
+    git submodule update --init
+    ```
+
+4.  **Set up the Python virtual environment and install dependencies:**
+
+    Using `uv`:
+    ```bash
+    uv sync --dev --no-install-package datafusion
+    source .venv/bin/activate
+    ```
+
+    Using `pip`:
+    ```bash
+    python3 -m venv .venv
+    source .venv/bin/activate
+    pip install -U pip
+    pip install -r pyproject.toml
+    ```
+
+### Building the Project
+
+To build the Rust code and install the Python package in development mode, run:
+
+```bash
+maturin develop
+```
+
+### Running Tests
+
+To run the Python tests, use `pytest`:
+
+```bash
+pytest
+```
+
+### Linting
+
+To run the linters, you can use the scripts in the `ci/scripts` directory:
+
+```bash
+./ci/scripts/python_lint.sh
+./ci/scripts/rust_clippy.sh
+./ci/scripts/rust_fmt.sh
+```