Source: https://databento.com/docs/api-historical/helpers/dbn-store-to-parquet


### DBNStore.to\_parquet

Write data to a file in [Apache parquet](https://parquet.apache.org/) format.

#### API method

```python
DBNStore.to_parquet(
    path: PathLike[str] | str,
    price_type: PriceType | str = "float",
    pretty_ts: bool = True,
    map_symbols: bool = True,
    schema: Schema | str | None = None,
    mode: Literal["w", "x"] = "w",
    **kwargs: Any,
) -> None
```

#### Parameters

| Parameter | Type | Required | Description |
| `path` | PathLike[str] or str | required | The file path to write the data to. |
| `price_type` | PriceType or str, default "float" | optional | The price type to use for price fields. If "fixed", prices will have a type of `int` in fixed decimal format; each unit representing 1e-9 or 0.000000001. If "float", prices will have a type of `float`. |
| `pretty_ts` | bool, default True | optional | Whether timestamp columns are converted to tz-aware `pyarrow.TimestampType` (UTC). |
| `map_symbols` | bool, default True | optional | If symbology mappings from the metadata should be used to create a 'symbol' column, mapping the instrument ID to its raw symbol for every record. |
| `schema` | Schema or str | optional | The data record [schema](https://databento.com/docs/schemas/whats-a-schema.md) for the output parquet file. Must be one of the values from [list\_schemas](https://databento.com/docs/api-historical/metadata/metadata-list-schemas.md). This is only required when reading a `DBNStore` with mixed record types. |
| `mode` | str | optional | The file write mode to use, either "x" or "w". Defaults to "w". |
| `**kwargs` | Any | optional | Keyword arguments to pass to [pyarrow.parquet.ParquetWriter](https://arrow.apache.org/docs/python/generated/pyarrow.parquet.ParquetWriter.html). These can be used to override the default behavior of the writer. |

#### Example usage

```python
import databento as db

client = db.Historical("$YOUR_API_KEY")

data = client.timeseries.get_range(
    dataset="GLBX.MDP3",
    symbols=["ESM2"],
    schema="trades",
    start="2022-06-06",
)

# Save streamed data to .parquet
data.to_parquet("GLBX-ESM2-20220606-trades.parquet")
```