# Polars 1.40.1 — Python Polars 1.40.1

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2026-04-22
- Version: 1.40.1
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.40.1
- Permalink: https://whatsnew.fyi/product/polars/releases/1.40.1

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** — Skip validity mask processing in __array_ufunc__ when no inputs have nulls
- **added** — Add maintain_order parameter to merge_sorted
- **fixed** — Honor having predicate in GroupBy iter
- **fixed** — Use the physical dtype for NumUnorderedImplodeReducer arrow ListArray
- **fixed** — Address bug in reduce_balanced for certain input length lists affecting pl.concat
- **fixed** — Ensure list.sample() allows fraction > 1 when with_replacement=True
- **fixed** — Ensure append() errors when upcast=False
- **fixed** — Always rechunk sorts, prune sorts even in eager execution
- **fixed** — Fix typing for DataFrame.__init__ and Series.__init__ so they don't require all optional dependencies to be installed

##### 🚀 Performance improvements

- Skip validity mask processing in \_\_array\_ufunc\_\_ when no inputs have nulls (#27358)

##### ✨ Enhancements

- Cargo deny (#27363)
- Add `maintain_order` parameter to `merge_sorted` (#27263)

##### 🐞 Bug fixes

- Honor `having` predicate in `GroupBy` iter (#27370)
- Use the physical dtype for `NumUnorderedImplodeReducer` arrow `ListArray` (#27375)
- Address bug in `reduce_balanced` for certain input length lists affecting `pl.concat` (#27352)
- Ensure `list.sample()` allows `fraction` > 1 when `with_replacement=True` (#27350)
- Ensure `append()` errors when `upcast=False` (#27346)
- Always rechunk sorts, prune sorts even in eager execution (#27356)
- Fix typing for `DataFrame.__init__` and `Series.__init__` so they don't require all optional dependencies to be installed (#27348)

##### 📖 Documentation

- Split out openlineage docs into guide and configuration (#27371)
- Add explanation on the observatory sqlite db file (#27354)

##### 🛠️ Other improvements

- Disable mypy type checking for `pyarrow` calls (#27377)
- Disable debug symbols in macos coverage tests (#27361)
- Cargo deny (#27363)

Thank you to all our contributors for making this release possible!
@EndPositive, @Kevin-Patyk, @MarcoGorelli, @carnarez, @dsprenkels, @gab23r, @jonathanchang31, @kdn36, @mzjp2 and @ritchie46