# Polars 1.33.0-beta.1 — Python Polars 1.33.0-beta.1

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-08-28
- Version: 1.33.0-beta.1
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.33.0-beta.1
- Permalink: https://whatsnew.fyi/product/polars/releases/1.33.0-beta.1
- Labels: Pre-release

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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- **removed** — Remove, deprecate or change eager Exprs to be lazy compatible
- **changed** — Always simplify order requirements in IR
- **changed** — Basic de-duplication of filter expressions
- **changed** — Cache the IR in pipe_with_schema
- **changed** — Lower arg_where natively to streaming engine
- **changed** — Lower Expr.shift to streaming engine
- **changed** — Lower order-preserving groupby to streaming engine
- **added** — Allow pl.Expr.log to take in an expression
- **added** — Add caching to user credential providers
- **added** — Expose mkdir parameter on write_parquet
- **added** — Implement diff() in streaming engine
- **added** — Enable Expr.diff(n) for negative n
- **added** — Allow upcasting null-typed columns to nested column types in scans
- **added** — Drop PyArrow requirement for write_database with the ADBC engine
- **deprecated** — Add a deprecation warning for pl.Series.shift(Null)
- **added** — Add LazyFrame.pipe_with_schema
- **added** — Add cum_* as native streaming nodes
- **added** — Add peak_{min,max} support for booleans
- **added** — Add DataFrame.map_columns for eager evaluation
- **fixed** — Correct size limits for Decimal cast
- **fixed** — Unordered unions in check order observing pass

##### 💥 Breaking changes

- Remove, deprecate or change eager `Expr`s to be lazy compatible (#24027)

##### 🚀 Performance improvements

- Always simplify order requirements in IR (#24192)
- Basic de-duplication of filter expressions (#24220)
- Cache the IR in `pipe_with_schema` (#24213)
- Lower `arg_where` natively to streaming engine (#24088)
- Lower Expr.shift to streaming engine (#24106)
- Lower order-preserving groupby to streaming engine (#24053)

##### ✨ Enhancements

- Allow pl.Expr.log to take in an expression (#24226)
- Add caching to user credential providers (#23789)
- Expose `mkdir` parameter on `write_parquet` (#24239)
- Implement diff() in streaming engine (#24189)
- Enable Expr.diff(n) for negative n (#24200)
- Allow upcasting null-typed columns to nested column types in scans (#24185)
- Log pyarrow predicate conversion result in sensitive verbose logs (#24186)
- Drop PyArrow requirement for `write_database` with the ADBC engine (#24136)
- Add a deprecation warning for pl.Series.shift(Null) (#24114)
- Improve Debug formatting of DataType (#24056)
- Add `LazyFrame.pipe_with_schema` (#24075)
- Catch additional temporal attributes in `BytecodeParser` function analysis (#24076)
- Add `cum_*` as native streaming nodes (#23977)
- Add peak\_{min,max} support for booleans (#24068)
- Add `DataFrame.map_columns` for eager evaluation (#23821)

##### 🐞 Bug fixes

- Correct size limits for Decimal cast (#24252)
- Unordered unions in check order observing pass (#24253)
- Fix dtype for `slice` on `Literal` in agg context (#24137)
- Fix incorrect `filter(lit(True))` when scanning hive (#24237)
- In-memory group\_by on 128-bit integers (#24242)
- Fix panic in `gather` inside groupby with invalid indices (#24182)
- Release the GIL in map\_groups (#24225)
- Remove extra explode in `LazyGroupBy.{head,tail}` (#24221)
- Fix panic in polars cloud CSV scan (#24197)
- Fix panic when loading categorical columns from IO plugin (#24205)
- Fix credential provider did not auto-init on partition sinks (#24188)
- Fix engine type for `concat_list` on AggScalar `implode` (#24160)
- Rolling\_mean handle centered weights with len(values) \< window\_size (#24158)
- Reading `is_in` predicate for Parquet plain strings (#24184)
- Support native DuckDB connection in read\_database (#24177)
- Make PyCategories pickleable (#24170)
- Remove unused unsound function `to_mutable_slice` (#24173)
- PyO3 extension types giving compat\_level errors (#24166)
- Allow non-elementwise by in top\_k (#24164)
- Fix `sort_by` for `group_by_dynamic` context (#24152)
- Input-independent length aggregations in streaming (#24153)
- Release GIL when iterating df in to\_arrow (#24151)
- Respect non-elementwise join\_where conditions (#24135)
- Fix mismatched pytest test collection error (#24133)
- Resolve schema mismatch for div on Boolean (#24111)
- Fix from\_repr parsing of negative durations (#24115)
- Make `group_by`/`partition_by` iterator keys `tuple[Any, ...]` to enable tuple-unpacking (#24113)
- Keep name when doing empty group-aware aggregation (#24098)
- Implode instead of `reshape_list` (#24078)
- Rolling mean with weights incorrect when min\_samples \< window\_size (#23485)
- Allow `merge_sorted` for all types (#24077)
- Include datatypes in `row_encode` expression (#24074)
- Include UDF materialized type in serialization (#24073)
- Correct `.rolling()` output type for non-aggregations (#24072)
- Correct planner output schema for `join_asof` (#24071)
- Correct output for `fold` and `reduce` (#24069)
- Expr.meta.output\_name for struct fields (#24064)
- Ensure upcast operations on `pl.Date` default to microsecond precision (#23981)
- Add peak\_{min,max} support for booleans (#24068)
- Planner output type for `mean` with strange input type (#24052)
- Remove, deprecate or change eager `Expr`s to be lazy compatible (#24027)

##### 📖 Documentation

- Fix formatting of Series.value\_counts examples (#24245)
- Add hint to use `DataFrame/Series` constructors in `from_

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