## Polars

| Variable                       | Description                                                                                           |
| ------------------------------ | ----------------------------------------------------------------------------------------------------- |
| `POLARS_ALLOW_PQ_EMPTY_STRUCT` | Allows reading or writing Parquet files that contain empty struct fields that are otherwise rejected. |
| `POLARS_TEMP_DIR`              | Override the default temporary directory Polars uses for scratch files and some I/O operations.       |

You may also set any Polars OSS-recognized environment variables.

## Polars on-premises

| Variable                   | Description                                                                                                                                                                                                     |
| -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `OTLP_ENDPOINT`            | Target endpoint for sending OTLP traces/metrics/logs to your OpenTelemetry collector/observability stack.<br>e.g. `http://otel-collector:4317`.                                                                 |
| `OTEL_SERVICE_INSTANCE_ID` | OpenTelemetry `service.instance.id` that uniquely identifies this cublet instance in telemetry.<br>Must match `cublet_id`.                                                                                      |
| `PLC_LOG_LEVEL`            | Controls logging verbosity for the Polars on-premises components (e.g. scheduler/worker).<br>e.g. `Info`, `Debug`, `Trace`, _etc._ (follows the Rust [naming](https://docs.rs/log/latest/log/enum.Level.html)). |
