# Polars 1.30.0 — Python Polars 1.30.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-05-21
- Version: 1.30.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.30.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.30.0

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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- **added** — Implement `list.filter` method
- **added** — Implement `LazyFrame.match_to_schema` method
- **added** — Add `nulls_equal` flag to `list/arr.contains`
- **added** — Add streaming cross-join node
- **added** — Add elementwise execution mode for `list.eval`
- **added** — Add options to write Parquet field metadata
- **added** — Add `cast_options` parameter to control type casting in `scan_parquet`
- **added** — Allow setting of regex size limit using `POLARS_REGEX_SIZE_LIMIT` environment variable
- **added** — Support reading and writing custom file-level parquet metadata
- **added** — Support grouping by `pl.Array`
- **changed** — Switch eligible casts to non-strict in optimizer
- **changed** — Allow predicate passing `set_sorted`
- **changed** — Increase default cross-file parallelism limit for new-streaming multiscan
- **changed** — Support optimised init from non-dict `Mapping` objects in `from_records` and frame/series constructors
- **changed** — Allow `.over` to be called without `partition_by`
- **changed** — Support binaryoffset in search sorted
- **changed** — Improved time-string parsing and inference generally and via the SQL interface
- **changed** — Support inference of `Int128` dtype from databases that support it
- **changed** — Allow casting `List<UInt8>` to `Binary`
- **fixed** — Fix RuntimeError when serializing the same DataFrame from multiple threads

##### 🚀 Performance improvements

- Switch eligible casts to non-strict in optimizer (#22850)
- Allow predicate passing set\_sorted (#22797)
- Increase default cross-file parallelism limit for new-streaming multiscan (#22700)
- Add elementwise execution mode for `list.eval` (#22715)
- Support optimised init from non-dict `Mapping` objects in `from_records` and frame/series constructors (#22638)
- Add streaming cross-join node (#22581)
- Switch off `maintain_order` in group-by followed by sort (#22492)

##### ✨ Enhancements

- Load AWS `endpoint_url` using boto3 (#22851)
- Implemented `list.filter` (#22749)
- Support binaryoffset in search sorted (#22786)
- Add `nulls_equal` flag to `list/arr.contains` (#22773)
- Implement `LazyFrame.match_to_schema` (#22726)
- Improved time-string parsing and inference (generally, and via the SQL interface) (#22606)
- Allow for `.over` to be called without `partition_by` (#22712)
- Support `AnyValue` translation from `PyMapping` values (#22722)
- Support optimised init from non-dict `Mapping` objects in `from_records` and frame/series constructors (#22638)
- Support inference of `Int128` dtype from databases that support it (#22682)
- Add options to write Parquet field metadata (#22652)
- Add `cast_options` parameter to control type casting in `scan_parquet` (#22617)
- Allow casting `List<UInt8>` to `Binary` (#22611)
- Allow setting of regex size limit using `POLARS_REGEX_SIZE_LIMIT` (#22651)
- Support use of literal values as "other" when evaluating `Series.zip_with` (#22632)
- Allow to read and write custom file-level parquet metadata (#21806)
- Support PEP702 `@deprecated` decorator behaviour (#22594)
- Support grouping by `pl.Array` (#22575)
- Preserve exception type and traceback for errors raised from Python (#22561)
- Use fixed-width font in streaming phys plan graph (#22540)

##### 🐞 Bug fixes

- Fix RuntimeError when serializing the same DataFrame from multiple threads (#22844)
- Fix map\_elements predicate pushdown (#22833)
- Fix reverse list type (#22832)
- Don't require numpy for search\_sorted (#22817)
- Add type equality checking for relevant methods (#22802)
- Invalid output for `fill_null` after `when.then` on structs (#22798)
- Don't panic for cross join with misaligned chunking (#22799)
- Panic on quantile over nulls in rolling window (#22792)
- Respect BinaryOffset metadata (#22785)
- Correct the output order of `PartitionByKey` and `PartitionParted` (#22778)
- Fallback to non-strict casting for deprecated casts (#22760)
- Clippy on new stable version (#22771)
- Handle sliced out remainder for bitmaps (#22759)
- Don't merge `Enum` categories on append (#22765)
- Fix unnest() not working on empty struct columns (#22391)
- Fix the default value type in `Schema` init (#22589)
- Correct name in `unnest` error message (#22740)
- Provide "schema" to `DataFrame`, even if empty JSON (#22739)
- Properly account for nulls in the `is_not_nan` check made in `drop_nans` (#22707)
- Incorrect result from SQL `count(*)` with `partition by` (#22728)
- Fix deadlock joining scanned tables with low thread count (#22672)
- Don't allow deserializing incompatible DSL (#22644)
- Incorrect null dtype from binary ops in empty group\_by (#22721)
- Don't mark `str.replace_many` with Mapping as deprecated (#22697)
- Gzip has maximum compression of 9, not 10 (#22685)
- Fix predicate pushdown of fallible expressions (#22669)
- Fix `index out of bounds` panic when scanning hugging face (#22661)
- Panic on `group_by` with literal and empty rows (#22621)
- Return input instead of panicking if empty subset in `drop_nulls()` and `drop_nans()` (#22469)
- Bump argminmax to 0.6.3 (#22649)
- DSL version deserialization endianness (#22642)
- Allow Expr.round() to be called on integer dtypes (#22622)
- Fix panic when filtering based on row index column in parquet (#22616)
- WASM and PyOdide compile (#22613)
- Resolve `get()` SchemaMismatch panic (#22350)
- Panic in group\_by\_dynamic on single-row df with group\_b

_[Truncated at 4000 characters — full notes: https://github.com/pola-rs/polars/releases/tag/py-1.30.0]_