python/adbc_driver_bigquery/README.md

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# ADBC BigQuery Driver for Python

This package contains bindings for the [BigQuery driver][bigquery], using
the [driver manager][driver-manager] to provide a [DBAPI 2.0/PEP
249-compatible][dbapi] interface on top.

[dbapi]: https://peps.python.org/pep-0249/
[driver-manager]: https://arrow.apache.org/adbc/current/python/driver_manager.html
[bigquery]: https://arrow.apache.org/adbc/current/driver/bigquery.html

## Building

Dependencies: a build of the BigQuery driver, and the
`adbc-driver-manager` Python package.  Optionally, install PyArrow to
use the DBAPI 2.0-compatible interface.

Set the environment variable `ADBC_BIGQUERY_LIBRARY` to the path to
`libadbc_driver_bigquery.{dll,dylib,so}` before running `pip install`.

```
# If not already installed
pip install -e ../adbc_driver_manager

export ADBC_BIGQUERY_LIBRARY=/path/to/libadbc_driver_bigquery.so
pip install --no-deps -e .
```

For users building from the arrow-adbc source repository, you can alternately use CMake to manage library dependencies and set environment variables for you. Assuming you specify ``-DADBC_DRIVER_BIGQUERY=ON`` you can also add ``-DADBC_BUILD_PYTHON=ON`` to define a ``python`` target.

For example, assuming you run cmake from the project root:

```shell
cmake -S c -B build --preset debug -DADBC_BUILD_PYTHON=ON -DADBC_DRIVER_BIGQUERY=ON
cmake --build build --target python
```

will properly build and install the Python library for you.

See [CONTRIBUTING.md](../../CONTRIBUTING.md) for details on the
general build process.

## Example

```python
import adbc_driver_bigquery.dbapi
from adbc_driver_bigquery import DatabaseOptions

db_kwargs = {
    DatabaseOptions.AUTH_TYPE.value: DatabaseOptions.AUTH_VALUE_CREDENTIALS_FILE,
    DatabaseOptions.CREDENTIALS.value: "credentials.json",
    DatabaseOptions.PROJECT_ID.value: "bigquery-poc-418913",
    DatabaseOptions.DATASET_ID.value: "google_trends",
    DatabaseOptions.TABLE_ID.value: "small_top_terms",
}
with adbc_driver_bigquery.dbapi.connect(db_kwargs) as conn:
    with conn.cursor() as cur:
        cur.execute("SELECT 1")
        print(cur.fetch_arrow_table())
```

## Testing

To run the tests, use pytest:

```shell
$ pytest -vvx
```

See [CONTRIBUTING.md](../../CONTRIBUTING.md) for details on the
general test process.