# Polars 1.43.0 — Python Polars 1.43.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2026-07-21
- Version: 1.43.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.43.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.43.0

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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- **deprecated** — Deprecate casting numeric types to categoricals
- **deprecated** — Deprecate cat.get_categories() and cat.to_local()
- **deprecated** — Deprecate LazyFrame.profile()
- **deprecated** — Deprecate casts from non-nested dtypes into Lists
- **deprecated** — Deprecate bitwise ops between integers and booleans
- **deprecated** — Deprecate list/arr.to_struct() calls that don't pass field names
- **changed** — Rename missing_utf8_is_empty_string to empty_string_is_null
- **changed** — Split multiplexers that directly scan from in-memory DataFrame
- **changed** — Make DNS cache global
- **changed** — Pre-partition on left, right and semi joins on hive partitioned data
- **changed** — Rewrite inner joins on hive partitioned data to a union of partitions filtered joins
- **added** — Add ewm_sum and ewm_sum_by
- **added** — Add scan_arrow_c_stream
- **added** — Support Iceberg field initial-default in native scan_iceberg
- **added** — Add Series.degrees/radians and clarify trig functions use radians
- **added** — Add list expression which consistently packs elements together into new List type
- **added** — Add Expr.cat.to and Expr.cat.physical
- **added** — Add POLARS_OOC_DISK_BUDGET_MB
- **added** — Add build side preference parameter for join
- **fixed** — Avoid panic when union slice skips all rows
- **fixed** — Solve panic in dt.replace when there were multiple chunks

##### ⚠️ Deprecations

- Deprecate casting numeric types to categoricals (#28349)
- Deprecate `cat.get_categories()` and `cat.to_local()` (#28299)
- Deprecate `LazyFrame.profile()` (#28275)
- Deprecate casts from non-nested dtypes into Lists (#28193)
- Deprecate bitwise ops between integers and booleans (#28186)
- Deprecate `list/arr.to_struct()` calls that don't pass field names (#28243)
- Rename `missing_utf8_is_empty_string` to `empty_string_is_null` (#28173)

##### 🚀 Performance improvements

- Split multiplexers that directly scan from in-memory DataFrame (#28376)
- Make DNS cache global (#28352)
- Do not remove cache if predicates not pushed to all inputs (#28341)
- Environment variable for logging slow DNS lookup (#28211)
- Pre-partition on left, right and semi joins on hive partitioned data (#28374)
- Rewrite inner joins on hive partitioned data to a union of partitions filtered joins (#28327)
- Tighten redundant comparisons and propagate filter constraints (#27999)
- Canonicalize predicates (#28212)
- Remove excess memory copy in streaming IPC sink (#28141)
- Parallelize scan\_iceberg resolve (#28168)
- Chunk-aware morsel splitting on single-file IO sink (#27950)
- Don't allocate for `full_null()` with small lengths (#28181)
- Use monotonic deque for rolling min\_by/max\_by (O(n)) (#27436)

##### ✨ Enhancements

- Pre-partition group-by on hive keys  (#28444)
- Add ewm\_sum and ewm\_sum\_by #28151 (#28215)
- Serve stale records from object\_store DNS cache (#28256)
- Make partition\_hive an opt flag (#28345)
- Add `scan_arrow_c_stream` (#28340)
- When displaying IRExprs, only add parentheses when needed for disambiguation (#28319)
- Support Iceberg field `initial-default` in native `scan_iceberg` (#28324)
- Show only differing dtypes in `assert_frame_equal` error (#27816)
- Expose ewm and rolling \*\_by expressions in Python visitor (#28286)
- More accurate rolling moments (#28309)
- Remove hard block on native scan for Iceberg V3 tables (#28277)
- Add Series.degrees/radians and clarify trig functions use radians (#22961)
- Merge sorted with multikey (#28067)
- Add `list` expression which consistently packs elements together into new List type (#27990)
- Add `read_database` Arrow fast-path for "python-oracledb" (#28230)
- Optimize joins with redundant equi-join keys (#28017)
- Implement missing datetime options for `CastColumnsPolicy` (#28084)
- Add Expr.cat.to and Expr.cat.physical (#28096)
- Add POLARS\_OOC\_DISK\_BUDGET\_MB (#28045)
- Add build side preference parameter for join (#28154)

##### 🐞 Bug fixes

- Avoid panic when union slice skips all rows (#28420)
- Solve panic in `dt.replace` when there were multiple chunks (#28437)
- Propagate `is_scalar` from the input to the output of `.sort()` and `.sort_by()` (#28438)
- Resolve CSV column names overwrite in DSL->IR conversion (#28383)
- Avoid IEJoin rewrite for Categorical comparisons (#28427)
- Do not rewrite `sort().reverse()` to `sort(descending=True)` when `maintain_order=True` (#28403)
- Ensure BinaryView offset+len does not exceed i32::MAX where possible (#28048)
- Invalid offset in strptime (#28388)
- Incorrect schema type for decimal \<-> primitive division (#28373)
- Panic in in-memory CSEE handling (#28371)
- Fix offset in arrow ffi export of sliced struct arrays (#28369)
- Fix cross filter not applied with sink and CSE (#28297)
- Fix panic on projection pushdown with caches (#28280)
- Fix `write_json()` null values in `Array` columns being written incorrectly as `null` (#28330)
- Fix EntityTooSmall on sink\_ipc to S3 (#28255)
- Raise error instead of silent wrapping for `select(len())` (#28355)
- Float16 groupby aggregates (#28361)
- Respect lexical ordering of Categorical in `top_k`/`bottom_k` (#28359)
- Support dtype-list schema overrides in scan\_csv (#28226)
- Resolve unknown type in fused multiply add (#28321)
- Honor `aws_checksum_algorithm` when provided (#28328)
- Remove usage of deprecated `pyarrow.feather.read_table` (#28323)
- Fix regress

_[Truncated at 4000 characters — full notes: https://github.com/pola-rs/polars/releases/tag/py-1.43.0]_