# Polars 1.26.0 — Python Polars 1.26.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-03-23
- Version: 1.26.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.26.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.26.0

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 views for binary hash tables and add single-key binary variant
- **changed** — Avoid rechunking in gather
- **changed** — Switch ahash for foldhash
- **changed** — Put THP behind feature flag
- **changed** — Enable THP by default
- **changed** — Improve join performance for expanding joins
- **changed** — Use binary_search instead of contains in business-day functions
- **added** — Add support for io-plugins in new-streaming
- **added** — Add PartitionParted
- **changed** — Minor improvements to EXPLAIN plan output
- **added** — Add explain_all
- **changed** — Allow to use repeat_by with nested lists and structs
- **fixed** — Fix DataFrame.nan_to_null work for tuple
- **fixed** — Allow pivot on empty frame for all integer index dtypes
- **fixed** — Fix null panic on decimal aggregate
- **fixed** — Fix join with categoricals on new-streaming engine
- **fixed** — Fix div 0 partitioned group-by
- **fixed** — Fix incorrect quote check in CSV parser
- **added** — Add option to use relative paths for plugin libraries
- **fixed** — Respect header separator in sink_csv

##### 🚀 Performance improvements

- Use views for binary hash tables and add single-key binary variant (#21872)
- Avoid rechunking in gather (#21876)
- Switch ahash for foldhash (#21852)
- Put THP behind feature flag (#21853)
- Enable THP by default (#21829)
- Improve join performance for expanding joins (#21821)
- Use binary\_search instead of contains in business-day functions (#21775)

##### ✨ Enhancements

- Add support for io-plugins in new-streaming (#21870)
- Add `PartitionParted` (#21788)
- Minor improvements to EXPLAIN plan output (#21822)
- Add `explain_all` (#21797)
- Allow to use `repeat_by` with (nested) lists and structs (#21206)

##### 🐞 Bug fixes

- Fix `DataFrame.nan_to_null` work for tuple (#21861)
- Allow `pivot` on empty frame for all integer index dtypes (#21890)
- Null panic on decimal aggregate (#21873)
- Join with categoricals on new-streaming engine (#21825)
- Fix div 0 partitioned group-by (#21842)
- Incorrect quote check in CSV parser (#21826)
- Add option to use relative paths for plugin libraries (#21675)
- Respect header separator in `sink_csv` (#21814)
- Deprecation of `streaming=False` (#21813)
- Fix collect\_all type-coercion (#21810)
- Memory leaks in SharedStorage (#21798)
- Make `None` refer to `uncompressed` in `sink_ipc` (#21786)

##### 📖 Documentation

- Add sources and sinks to user-guide (#21780)

##### 🛠️ Other improvements

- Change dynamic literals to be separate category (#21849)
- Add POLARS\_TIMEOUT\_MS for timing out slow Polars tests (#21887)
- Disable --dist loadgroup in pytest (#21885)
- Fix refcount assert being messed up by pytest assertion magic (#21884)
- Add env vars to configure new-streaming buffer sizes (#21818)

Thank you to all our contributors for making this release possible!
@Kevin-Patyk, @MarcoGorelli, @alexander-beedie, @anath2, @borchero, @coastalwhite, @dongchao-cn, @kgv, @mcrumiller, @nameexhaustion, @orlp and @ritchie46