Add PyCapsule Protocol support for Arrow inputs #1265
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- Add Protocol types for Arrow PyCapsule Interface - Update schema parameters to accept any Arrow-compatible library - Move pyarrow to TYPE_CHECKING (optional at runtime)
kylebarron
reviewed
Oct 7, 2025
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I'm not sure we can remove the dependency unless we do something about our auto-literal conversion. I suspect there are other places. https://github.com/apache/datafusion-python/blob/main/python/datafusion/expr.py#L563 |
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Perhaps we should add support for the protocol without removing the pyarrow dependency yet |
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I've updated the PR based on your feedback. PyArrow will stay required for now. That way people can at least use nanoarrow/Polars schemas, and we can tackle making PyArrow fully optional down the road. All tests passing! Let me know if you'd like any other changes. I am also happy to break this into smaller steps and handle the full optional PyArrow work in follow up issues. |
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Which issue does this PR close?
Closes #1227
Rationale for this change
(From original issue)
PyArrow is a massive dependency (>100MB unpacked) and the only required dependency for datafusion-python. Many Python Arrow libraries implement the PyCapsule Interface, allowing users to choose lightweight alternatives like nanoarrow (~7MB), arro3, or pass data directly from Polars, DuckDB, etc.
This PR implements the first phase of making PyArrow optional by updating input parameters to accept any Arrow-compatible library via the PyCapsule Interface.
What changes are included in this PR?
ArrowSchemaExportableregister_csv,register_parquet,register_json,register_avro,register_listing_table, and read methods to acceptArrowSchemaExportableTYPE_CHECKINGblock (optional at runtime for type hints only)Note: This PR covers input parameters only. Return types (ToPyArrow conversions) still reference pyarrow and will be addressed in a follow-up PR.
Are there any user-facing changes?
Breaking changes: None. All existing PyArrow usage continues to work.
New functionality: Users can now pass Arrow schemas from any library implementing
__arrow_c_schema__()(nanoarrow, arro3, Polars, DuckDB, etc.) to datafusion methods.Type hints: Schema parameters now show
ArrowSchemaExportable | Noneinstead ofpa.Schema | None, but accept both.