polars.LazyFrame.sink_ndjson#

LazyFrame.sink_ndjson(
path: str | Path,
*,
maintain_order: bool = True,
type_coercion: bool = True,
predicate_pushdown: bool = True,
projection_pushdown: bool = True,
simplify_expression: bool = True,
slice_pushdown: bool = True,
collapse_joins: bool = True,
no_optimization: bool = False,
storage_options: dict[str, Any] | None = None,
credential_provider: CredentialProviderFunction | Literal['auto'] | None = 'auto',
retries: int = 2,
) → None[source]#

Evaluate the query in streaming mode and write to an NDJSON file.

Warning

Streaming mode is considered unstable. It may be changed at any point without it being considered a breaking change.

This allows streaming results that are larger than RAM to be written to disk.

Parameters:
path

File path to which the file should be written.

maintain_order

Maintain the order in which data is processed. Setting this to False will be slightly faster.

type_coercion

Do type coercion optimization.

predicate_pushdown

Do predicate pushdown optimization.

projection_pushdown

Do projection pushdown optimization.

simplify_expression

Run simplify expressions optimization.

slice_pushdown

Slice pushdown optimization.

collapse_joins

Collapse a join and filters into a faster join

no_optimization

Turn off (certain) optimizations.

storage_options

Options that indicate how to connect to a cloud provider.

The cloud providers currently supported are AWS, GCP, and Azure. See supported keys here:

  • aws

  • gcp

  • azure

  • Hugging Face (hf://): Accepts an API key under the token parameter: {'token': '...'}, or by setting the HF_TOKEN environment variable.

If storage_options is not provided, Polars will try to infer the information from environment variables.

credential_provider

Provide a function that can be called to provide cloud storage credentials. The function is expected to return a dictionary of credential keys along with an optional credential expiry time.

Warning

This functionality is considered unstable. It may be changed at any point without it being considered a breaking change.

retries

Number of retries if accessing a cloud instance fails.

Returns:
DataFrame

Examples

>>> lf = pl.scan_csv("/path/to/my_larger_than_ram_file.csv")  
>>> lf.sink_ndjson("out.ndjson")