py-1.35.0

## 🏆 Highlights

- Stabilize decimal (#25020)

## 🚀 Performance improvements

- Bump foldhash to 0.2.0 and hashbrown to 0.16.0 (#25014)
- Lower `unique` to native group-by and speed up `n_unique` in group-by context (#24976)
- Better parallelize `take{_slice,}_unchecked` (#24980)
- Implement native `skew` and `kurtosis` in group-by context (#24961)
- Use native group-by aggregations for `bitwise_*` operations (#24935)
- Address `group_by_dynamic` slowness in sparse data (#24916)
- Push filters to PyIceberg (#24910)
- Native `filter/drop_nulls/drop_nans` in group-by context (#24897)
- Implement `cumulative_eval` using the group-by engine (#24889)
- Prevent generation of copies of `Dataframe`s in `DslPlan` serialization (#24852)
- Implement native `null_count`, `any` and `all` group-by aggregations (#24859)
- Speed up `reverse` in group-by context (#24855)
- Prune unused categorical values when exporting to arrow/parquet/IPC/pickle (#24829)
- Don't check duplicates on streaming simple projection in release mode (#24830)
- Lower approx\_n\_unique to the streaming engine (#24821)
- Duration/interval string parsing optimisation (2-5x faster) (#24771)
- Use native reducer for `first/last` on Decimals, Categoricals and Enums (#24786)
- Implement indexed method for `BitMapIter::nth` (#24766)
- Pushdown slices on plans within unions (#24735)

## ✨ Enhancements

- Stabilize decimal (#25020)
- Support `ewm_mean()` in streaming engine (#25003)
- Improve row-count estimates (#24996)
- Remove filtered scan paths in IR when possible (#24974)
- Introduce remote Polars MCP server (#24977)
- Allow local scans on polars cloud (configurable) (#24962)
- Add `Expr.item` to strictly extract a single value from an expression (#24888)
- Add environment variable to roundtrip empty struct in Parquet (#24914)
- Fast-count for `scan_iceberg().select(len())` (#24602)
- Add `glob` parameter to `scan_ipc` (#24898)
- Prevent generation of copies of `Dataframe`s in `DslPlan` serialization (#24852)
- Add `list.agg` and `arr.agg` (#24790)
- Implement `{Expr,Series}.rolling_rank()` (#24776)
- Don't require PyArrow for `read_database_uri` if ADBC engine version supports PyCapsule interface (#24029)
- Make `Series` init consistent with `DataFrame` init for string values declared with temporal dtype (#24785)
- Support MergeSorted in CSPE (#24805)
- Duration/interval string parsing optimisation (2-5x faster) (#24771)
- Recursively apply CSPE (#24798)
- Add streaming engine per-node metrics (#24788)
- Add `arr.eval` (#24472)
- Drop PyArrow requirement for non-batched usage of `read_database` with the ADBC engine and support `iter_batches` with the ADBC engine (#24180)
- Improve rolling\_(sum|mean) accuracy (#24743)
- Add `separator` to `{Data,Lazy}Frame.unnest` (#24716)
- Add `union()` function for unordered concatenation (#24298)
- Add `name.replace` to the set of column rename options (#17942)
- Support `np.ndarray -> AnyValue` conversion (#24748)
- Allow duration strings with leading "+" (#24737)
- Drop now-unnecessary post-init "schema\_overrides" cast on `DataFrame` load from list of dicts (#24739)
- Add support for UInt128 to pyo3-polars (#24731)

## 🐞 Bug fixes

- Re-enable CPU feature check before import (#25010)
- Implement `read_excel` workaround for fastexcel/calamine issue loading a column subset from a named table (#25012)
- Correctness `any(ignore_nulls)` and OOB in `all` (#25005)
- Streaming any/all with ignore\_nulls=False (#25008)
- Fix incorrect `join_asof` on a casted expression (#25006)
- Optimize memory on rolling groups in `ApplyExpr` (#24709)
- Fallback `Pyarrow` scan to in-memory engine (#24991)
- Make `Operator::swap_operands` return correct operators for `Plus`, `Minus`, `Multiply` and `Divide` (#24997)
- Capitalize letters after numbers in to\_titlecase (#24993)
- Preserve null values in `pct_change` (#24952)
- Raise length mismatch on `over` with sliced groups (#24887)
- Check duplicate name in transpose (#24956)
- Follow Kleene logic in `any` / `all` for group-by (#24940)
- Do not optimize cross join to iejoin if order maintaining (#24950)
- Fix typing of `scan_parquet` partially unknown (#24928)
- Properly release the GIL for `read_parquet_metadata` (#24922)
- Broadcast `partition_by` columns in `over` expression (#24874)
- Clear index cache on stacked `df.filter` expressions (#24870)
- Fix 'explode' mapping strategy on scalar value (#24861)
- Fix repeated `with_row_index()` after `scan()` silently ignored (#24866)
- Correctly return min and max for enums in groupby aggregation (#24808)
- Refactor `BinaryExpr` in `group_by` dispatch logic (#24548)
- Fix aggstate for `gather` (#24857)
- Keep scalars for length preserving functions in `group_by` (#24819)
- Have `range` feature depend on `dtype-array` feature (#24853)
- Fix duplicate select panic (#24836)
- Inconsistency of list.sum() result type with None values (#24476)
- Division by zero in Expr.dt.truncate (#24832)
- Potential deadlock in \_\_arrow\_c\_stream\_\_ (#24831)
- Allow double aggregations in group-by contexts (#24823)
- Series.shrink\_dtype for i128/u128 (#24833)
- Fix dtype in `EvalExpr` (#24650)
- Allow aggregations on `AggState::LiteralScalar` (#24820)
- Dispatch to `group_aware` for fallible expressions with masked out elements (#24815)
- Fix error for `arr.sum()` on small integer Array dtypes containing nulls (#24478)
- Fix regression on `write_database()` to Snowflake due to unsupported string view type (#24622)
- Fix XOR did not follow kleene when one side is unit-length (#24810)
- Make `Series` init consistent with `DataFrame` init for string values declared with temporal dtype (#24785)
- Incorrect precision in Series.str.to\_decimal (#24804)
- Use `overlapping` instead of `rolling` (#24787)
- Fix iterable on `dynamic_group_by` and `rolling` object (#24740)
- Use Kahan summation for in-memory groupby sum/mean (#24774)
- Release GIL in PythonScan predicate evaluation (#24779)
- Type error in `bitmask::nth_set_bit_u64` (#24775)
- Add `Expr.sign` for `Decimal` datatype (#24717)
- Correct `str.replace` with missing pattern (#24768)
- Ensure `schema_overrides` is respected when loading iterable row data (#24721)
- Support `decimal_comma` on `Decimal` type in `write_csv` (#24718)

## 📖 Documentation

- Introduce remote Polars MCP server (#24977)
- Add `{arr,list}.agg` API references (#24970)
- Support LLM in docs (#24958)
- Update Cloud docs with correct fn argument order (#24939)
- Update `name.replace` examples (#24941)
- Add i128 and u128 features to user guide (#24938)
- Add partitioning examples for `sink_*` methods (#24918)
- Add more `{unique,value}_counts` examples (#24927)
- Indent the versionchanged (#24783)
- Relax fsspec wording (#24881)
- Add `pl.field` into the api docs (#24846)
- Fix duplicated article in SECURITY.md (#24762)
- Document output name determination in when/then/otherwise (#24746)
- Specify that precision=None becomes 38 for Decimal (#24742)
- Mention polars[rt64] and polars[rtcompat] instead of u64-idx and lts-cpu (#24749)
- Fix source mapping (#24736)

## 📦 Build system

- Ensure `build_feature_flags.py` is included in artifact (#25024)
- Update pyo3 and numpy crates to version 0.26 (#24760)

## 🛠️ Other improvements

- Fix benchmark ci (#25019)
- Fix non-deterministic test (#25009)
- Fix makefile arch detection (#25011)
- Make `LazyFrame.set_sorted` into a `FunctionIR::Hint` (#24981)
- Remove symbolic links (#24982)
- Deprecate `Expr.agg_groups()` and `pl.groups()` (#24919)
- Dispatch to no-op rayon thread-pool from streaming (#24957)
- Unpin pydantic (#24955)
- Ensure safety of scan fast-count IR lowering in streaming (#24953)
- Re-use iterators in `set_` operations (#24850)
- Remove `GroupByPartitioned` and dispatch to streaming engine (#24903)
- Turn `element()` into `{A,}Expr::Element` (#24885)
- Pass `ScanOptions` to `new_from_ipc` (#24893)
- Update tests to be index type agnostic (#24891)
- Unset `Context` in `Window` expression (#24875)
- Fix failing delta test (#24867)
- Move `FunctionExpr` dispatch from `plan` to `expr` (#24839)
- Fix SQL test giving wrong error message (#24835)
- Consolidate dtype paths in `ApplyExpr` (#24825)
- Add `days_in_month` to documentation (#24822)
- Enable ruff D417 lint (#24814)
- Turn `pl.format` into proper elementwise expression (#24811)
- Fix remote benchmark by no-longer saving builds (#24812)
- Refactor `ApplyExpr` in `group_by` context on multiple inputs (#24520)
- IR text plan graph generator (#24733)
- Temporarily pin pydantic to fix CI (#24797)
- Extend and rename `rolling` groups to `overlapping` (#24577)
- Refactor `DataType` `proptest` strategies (#24763)
- Add `union` to documentation (#24769)

Thank you to all our contributors for making this release possible!
@EndPositive, @EnricoMi, @JakubValtar, @Kevin-Patyk, @MarcoGorelli, @Object905, @alexander-beedie, @borchero, @carnarez, @cmdlineluser, @coastalwhite, @craigalodon, @dsprenkels, @eitsupi, @etrotta, @henryharbeck, @jordanosborn, @kdn36, @math-hiyoko, @mjanssen, @nameexhaustion, @orlp, @pavelzw, @r-brink, @ritchie46, @thomasjpfan and @williambdean