# Polars 1.19.0 — Python Polars 1.19.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2025-01-03
- Version: 1.19.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.19.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.19.0

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'.

---

- **added** — Add Int128 IO support for csv and ipc
- **added** — Support arbitrary expressions in join_where
- **added** — Add an include_file_paths parameter to read_excel and read_ods
- **added** — Allow loading data from multiple Excel/ODS workbooks and worksheets
- **added** — Implement list.min and list.max for list[i128]
- **changed** — Allow use of Python types in cs.by_dtype and col
- **changed** — Accept more generic Iterable[bool] in Series.filter
- **changed** — Allow more join lossless casting
- **changed** — Collapse expanded filters in eager
- **changed** — Use different binview dedup strategy depending on chunks ratio
- **changed** — Re-enable common subplan elim for new-streaming engine
- **fixed** — Output index type instead of u32 for sum_horizontal with boolean inputs
- **fixed** — Fix more global categorical issues
- **fixed** — Revert categorical unique code
- **fixed** — Add unique fast path for empty categoricals
- **fixed** — Fix various Int128 operations
- **fixed** — Fix global cat unique
- **fixed** — Fix union
- **fixed** — Fix rolling aggregations for various integer types
- **fixed** — Ensure ignore_nulls is respected in horizontal sum/mean

##### 🚀 Performance improvements

- Collapse expanded filters in eager (#20493)
- Remove predicate from `IR::DataFrame` (#20492)
- Use different binview dedup strategy depending on chunks ratio (#20451)
- Generalize the `arg_sort` fast path onto `Column` (#20437)
- Dedup binviews up front (#20449)
- Re-enable common subplan elim for new-streaming engine (#20443)
- Don't collect all LHS arrays in gather (#20441)
- Remove prepare\_series for gather kernels (#20439)
- Don't always take all data buffers when gathering views (#20435)

##### ✨ Enhancements

- Add `Int128` IO support for csv \& ipc (#20535)
- Support arbitrary expressions in 'join\_where' (#20525)
- Allow use of Python types in `cs.by_dtype` and `col` (#20491)
- Add an "include\_file\_paths" parameter to `read_excel` and `read_ods` (#20476)
- Allow more join lossless casting (#20474)
- Accept more generic `Iterable[bool]` in Series.filter (#20431)
- Allow loading data from multiple Excel/ODS workbooks and worksheets (#20465)

##### 🐞 Bug fixes

- Output index type instead of u32 for `sum_horizontal` with boolean inputs (#20531)
- Fix more global categorical issues (#20547)
- Update eager join doctest on multiple columns (#20542)
- Revert categorical unique code (#20540)
- Add `unique` fast path for empty categoricals (#20536)
- Fix various `Int128` operations (#20515)
- Fix global cat unique (#20524)
- Fix union (#20523)
- Fix rolling aggregations for various integer types (#20512)
- Ensure `ignore_nulls` is respected in horizontal sum/mean (#20469)
- Fix incorrectly added sorted flag after append for lexically ordered categorical series (#20414)
- More `Int128` testing and related fixes (#20494)
- Validate column names in `unique()` for empty DataFrames (#20411)
- Implement `list.min` and `list.max` for `list[i128]` (#20488)
- Decimal from physical in horizontal min/max and shift (#20487)
- Don't remove sort if first/last strategy is set in unique (#20481)
- Fix join literal behavior (#20477)
- Validate asof join by args in IR resolving phase (#20473)
- Fix `align_frames` with single row panicking (#20466)
- Allow multiple column sort for Decimal (#20452)
- Fix mode panicking for String dtype (#20458)
- Return correct schema for `sum_horizontal` with boolean dtype (#20459)
- Fix return type for `add_business_days`, `millennium`, `century` and `combine` methods in `Series.dt` namespace (#20436)

##### 📖 Documentation

- Fix typo in `DataFrame.cast` (#20532)
- Fix flaky doctests (#20516)
- Add examples for bitwise expressions (#20503)
- Clarify the join pre-condition of `join_asof` (#20509)
- Fix `Expr.all` description of Kleene logic (#20409)

##### 🛠️ Other improvements

- Increase categorical test coverage (#20514)
- Report wheel sizes (#20541)
- Add tests for `floor/ceil` on integers (#20479)
- Expose and rewrite 'can\_pre\_agg' (#20450)
- Skip test on windows; kuzu import segfaults (#20463)
- Add a `TypeCheckRule` to the optimizer (#20425)

Thank you to all our contributors for making this release possible!
@Biswas-N, @IndexSeek, @Prathamesh-Ghatole, @Terrigible, @alexander-beedie, @brifitz, @coastalwhite, @dependabot, @dependabot[bot], @jqnatividad, @lukemanley, @mcrumiller, @orlp, @ritchie46 and @siddharth-vi