# Polars 1.33.1 — Python Polars 1.33.1

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-09-09
- Version: 1.33.1
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.33.1
- Permalink: https://whatsnew.fyi/product/polars/releases/1.33.1

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **changed** — Use specialized decoding for all predicates for Parquet dictionary encoding
- **changed** — Allocate only for read items when reading Parquet with predicate
- **changed** — Don't aggregate groups for strict cast if original len
- **added** — Support S3 virtual-hosted–style URI
- **changed** — Remove explicit file create for local async writes
- **added** — Add PyCapsule `__arrow_c_schema__` interface to `pl.Schema`
- **added** — Support Partitioning sinks in cloud
- **added** — User-friendly error message on empty path expansion
- **added** — Add unstable `pre_execution_query` parameter to `read_database_uri`
- **fixed** — Correct `sink_ipc` overload for compression
- **changed** — Enable all integer dtypes for `by` parameter in `join_asof`
- **fixed** — Fix Group-By + filter aggregation performs subsequent operations on all data instead of only filtered data
- **fixed** — Wrap deprecated top-level imports in TYPE_CHECKING
- **fixed** — Fix incorrect output ordering for row-separable exprs
- **fixed** — Fix `Series.__arrow_c_stream__` for Decimal and other logical types
- **fixed** — Match output type to engine for `Struct` arithmetic
- **fixed** — Make mmap use MAP_PRIVATE rather than MAP_SHARED
- **fixed** — Fix cloud iceberg scan DATASET_PROVIDER_VTABLE error
- **fixed** — Don't throw away type information for NumPy numeric values when using lit()
- **fixed** — Fix incorrect logic in negative streaming slice

##### 🚀 Performance improvements

- Use specialized decoding for all predicates for Parquet dictionary encoding (#24403)
- Allocate only for read items when reading Parquet with predicate (#24401)
- Don't aggregate groups for strict cast if original len (#24381)
- Allocate only for read items when reading Parquet with predicate (#24324)

##### ✨ Enhancements

- Support S3 virtual-hosted–style URI (#24405)
- Remove explicit file create for local async writes (#24358)
- Add PyCapsule `__arrow_c_schema__` interface to `pl.Schema` (#24365)
- Support Partitioning sinks in cloud (#24399)
- User-friendly error message on empty path expansion (#24337)
- Add unstable `pre_execution_query` parameter to `read_database_uri` (#23634)
- Add Polars security policy (#24314)

##### 🐞 Bug fixes

- Correct `sink_ipc` overload for compression (#24398)
- Enable all integer dtypes for `by` parameter in `join_asof` (#24384)
- Fix Group-By + filter aggregation performs subsequent operations on all data instead of only filtered data (#24373)
- Wrap deprecated top-level imports in TYPE\_CHECKING (#24340)
- Fix incorrect output ordering for row-separable exprs (#24354)
- Fix `Series.__arrow_c_stream__` for Decimal and other logical types (#24120)
- Match output type to engine for `Struct` arithmetic (#23805)
- Make mmap use MAP\_PRIVATE rather than MAP\_SHARED (#24343)
- Fix cloud iceberg scan DATASET\_PROVIDER\_VTABLE error (#24338)
- Don't throw away type information for NumPy numeric values when using lit() (#24229)
- Incorrect logic in negative streaming slice (#24326)
- Ensure `read_database_uri` with ADBC works as expected with DuckDB URIs (#24097)
- Do not error on non-list `Sequence` for `columns` parameter in `read_excel` (#23967)

##### 📖 Documentation

- Document newly added `is_pure` parameter for `register_io_source` (#24311)
- Create a module docstring for the public `polars` module (#24332)
- Update to Polars Cloud user guide (#24187)
- Update distributed page (#24323)
- Add a note and example about exporting unformatted `Excel` sheet data (#24145)
- Add detail about server-side cursor behaviour for SQLAlchemy in the "iter\_batches" parameter of `read_database` (#24094)
- Add Polars security policy (#24314)

##### 🛠️ Other improvements

- Bump c-api (#24412)
- Add a regression test for #7631 (#24363)
- Update cloud test `InteractiveQuery` to `DirectQuery` (#24287)
- Mark some tests as slow (#24327)
- Mark more tests as ready for cloud (#24315)
- Add hint to update `PYPOLARS_VERSION` on version assert test (#24313)

Thank you to all our contributors for making this release possible!
@Kevin-Patyk, @VictorAtIfInsurance, @alexander-beedie, @coastalwhite, @dsprenkels, @itamarst, @kdn36, @kuril, @mcrumiller, @nameexhaustion, @nesb1, @orlp, @r-brink and @ritchie46