# Polars 1.43.1 — Python Polars 1.43.1

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2026-07-27
- Version: 1.43.1
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.43.1
- Permalink: https://whatsnew.fyi/product/polars/releases/1.43.1

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** — Optimize not(bool_f) to not_bool_f
- **added** — Allow callback sinks on cloud
- **fixed** — Fix panic on self join of scan_delta / scan_iceberg
- **fixed** — Fix UB on first/last_non_null with empty chunk
- **fixed** — Do not CSE non-column height expr on streaming engine
- **fixed** — Propagate adjusted sortedness through Gather
- **fixed** — Deduplicate the expression equality checks
- **fixed** — Address 3VL issue with SQL NOT IN interaction with NULL values and joins
- **fixed** — Use total comparison in Expr literal values
- **fixed** — Ensure SQL SUM and CORR aggregates return NULL for all-null inputs, add TOTAL
- **fixed** — Share null_count_dtype helper between Delta and Iceberg, fixing SchemaError
- **fixed** — Remove non-output columns from the equi-join and semi/anti-join operators
- **fixed** — Fix dropped slice on multiple unions
- **fixed** — Fix in-memory engine incorrect slice on maintain order join
- **fixed** — Check join schema by position
- **fixed** — Block predicate pushdown past overwritten window keys
- **added** — Make hive_part extraction a function and public

##### 🚀 Performance improvements

- Optimize not(bool\_f) to not\_bool\_f (#28474)

##### ✨ Enhancements

- Allow callback sinks on cloud (#28458)

##### 🐞 Bug fixes

- Fix panic on self join of scan\_delta / scan\_iceberg (#28468)
- Fix UB on first/last\_non\_null with empty chunk (#28495)
- Do not CSE non-column height expr on streaming engine (#28480)
- Propagate adjusted sortedness through Gather (#28493)
- Deduplicate the expression equality checks (#28483)
- Address 3VL issue with SQL `NOT IN` interaction with `NULL` values and joins (#28484)
- Use total comparison in Expr literal values (#28482)
- Ensure SQL `SUM` and `CORR` aggregates return NULL for all-null inputs, add `TOTAL` (#28475)
- Share `null_count_dtype` helper between Delta and Iceberg, fixing `SchemaError` (#28479)
- Remove non-output columns from the equi-join and semi/anti-join operators (#28446)
- Fix dropped slice on multiple unions (#28477)
- Fix in-memory engine incorrect slice on maintain order join (#28478)
- Check join schema by position (#28455)
- Block predicate pushdown past overwritten window keys (#28429)

##### 📖 Documentation

- Update and restructure README (#28490)
- Minor fixes to Spark migration guide (#27730)
- Relocate Polars Cloud \& On-Prem User Guide (#28462)
- Add notes on k8s operator (#28445)

##### 🛠️ Other improvements

- Make hive\_part extraction a function and public (#28507)
- Deduplicate the expression equality checks (#28483)
- Bump `ruff` and `mypy` package versions (#28456)
- Fix flaky test (#28454)

Thank you to all our contributors for making this release possible!
@AnirudhRahul, @EndPositive, @Jesse-Bakker, @alexander-beedie, @carnarez, @dancsi, @mdroogh, @mroeschke, @nameexhaustion, @nchammas, @orlp, @r-brink and @ritchie46