# Polars 1.30.0-beta.1 — Python Polars 1.30.0-beta.1

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-05-16
- Version: 1.30.0-beta.1
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.30.0-beta.1
- Permalink: https://whatsnew.fyi/product/polars/releases/1.30.0-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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- **changed** — Increase default cross-file parallelism limit for new-streaming multiscan
- **changed** — Add elementwise execution mode for list.eval
- **changed** — Support optimised init from non-dict Mapping objects in from_records and frame/series constructors
- **added** — Add streaming cross-join node
- **changed** — Switch off maintain_order in group-by followed by sort
- **added** — Support binaryoffset in search sorted
- **added** — Add nulls_equal flag to list/arr.contains
- **added** — Implement LazyFrame.match_to_schema
- **changed** — Improve time-string parsing and inference generally and via the SQL interface
- **changed** — Allow for .over to be called without partition_by
- **added** — Support AnyValue translation from PyMapping values
- **added** — Support inference of Int128 dtype from databases that support it
- **added** — Add options to write Parquet field metadata
- **added** — Add cast_options parameter to control type casting in scan_parquet
- **changed** — Allow casting List<UInt8> to Binary
- **added** — Allow setting of regex size limit using POLARS_REGEX_SIZE_LIMIT
- **changed** — Support use of literal values as "other" when evaluating Series.zip_with
- **added** — Allow to read and write custom file-level parquet metadata
- **added** — Support PEP702 @deprecated decorator behaviour
- **added** — Support grouping by pl.Array

##### 🚀 Performance improvements

- 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

- 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

- 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\_by (#22597)
- Add `new_streaming` feature to `polars` crate (#22601)
- Consistently use Unix epoch as origin for ``dt.truncate`` (except weekly buckets which start on Mondays) (#22592)
- Fix interpolate on dtype Decimal (#22541)
- CSV count rows skipped last line if file did not end with newline (#22577)
- Make nested strict casting actually strict (#22497)
- Make `replace` and `replace_strict` mapping use list literals (#22566)
- Allow pivot on `Time` column (#22550)
- Fix error when providing CSV schema with extra columns (#22544)
- Panic on bitwise op between Series and Expr (#22527)
- Multi-selector regex expansion (#22542)

##### 📖 Documentation

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