# Polars 1.41.0 — Python Polars 1.41.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2026-05-22
- Version: 1.41.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.41.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.41.0

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** — Add LazyFrame.gather
- **added** — Add Expr.is_empty
- **added** — Add support for the SQL FILTER clause for aggregate functions, and STRING_AGG
- **added** — Add null_on_oob in {Expr/Series}.gather
- **added** — Add Rust backend for Expr.has_nulls
- **added** — Add streaming GatherNode
- **changed** — Stabilize streaming engine
- **changed** — Stabilize float16
- **changed** — Use true division for the / operator in Polars SQL
- **changed** — Dispatch {list,arr}.{unique,n_unique,reverse} to group_by engine
- **changed** — Speed up parquet metadata decode with hand-written Thrift
- **fixed** — Panic in scan of empty IPC with slice
- **fixed** — Persist object_store rebuild state in cache
- **fixed** — Sort flag on GroupsType only applies to first element
- **fixed** — Don't unwrap channel send in streaming join_asof
- **fixed** — Fix merge_sorted panic when List in frame
- **fixed** — Raise TypeError when calling next() directly on GroupBy objects
- **fixed** — Data type comparison for extension types
- **fixed** — Prevent panic when switching from one extension dtype to another
- **deprecated** — Deprecate the StringCache

##### 🏆 Highlights

- Add LazyFrame.gather (#27501)
- Nested common subplan elimination (#27340)
- Stabilize streaming engine (#27497)
- Speed up parquet metadata decode with hand-written Thrift (#27427)

##### ⚠️ Deprecations

- Deprecate the StringCache (#27580)

##### 🚀 Performance improvements

- Dispatch `{list,arr}.{unique,n_unique,reverse}` to group\_by engine (#27278)
- Improve in-memory grouped non-null count (#27702)
- Factor shared conjuncts out of OR-of-ANDs predicates (#27627)
- Skip downloading IPC batches exceeding slice bounds (#27683)
- Avoid materializing broadcast list in `list.shift` (#27628)
- Optimise `json_decode` Datetime string parsing (#27559)
- Speed up `to_numpy` C-order via cache-blocked transpose (#27522)
- Optimize `select(len())` for non-strict horizontal concat (#27516)
- Pushdown slices to inputs on left/right/full join (#27508)
- Don't infer CSV schema if schema is set (#27507)
- Nested common subplan elimination (#27340)
- Make `is_in` row-group pruning precise on null-containing haystacks (#27495)
- Don't do fused-multiply-add on scalars (#27479)
- List full fast path (#27477)
- Make `is_in` row-group pruning precise on multi-value lists (#27475)
- Add streaming GatherNode (#27465)
- Lower non-elementwise FunctionExprIR to ColumnarFunctionNode (#27462)
- Speed up parquet metadata decode with hand-written Thrift (#27427)

##### ✨ Enhancements

- Use true division for the `/` operator in Polars SQL (#27391)
- Add Rust backend for Expr.has\_nulls (#27590)
- Stabilize float16 (#27607)
- Add Expr.is\_empty (#27583)
- Add support for the SQL `FILTER` clause for aggregate functions, and `STRING_AGG` (#27564)
- Make parquet `FileMetadata` prunable for IR-plan dispatch (#27535)
- Broadcast scalar input for `list.slice` (#27487)
- Add LazyFrame.gather (#27501)
- Add `null_on_oob` in {Expr/Series}.gather (#27327)
- Stabilize streaming engine (#27497)
- Process batched `arr.eval` on overflow boundaries (#27496)
- Process batched `list.eval` on overflow boundaries (#27483)
- Print `SLICED UNION` in LazyFrame explain (#27467)

##### 🐞 Bug fixes

- Panic in scan of empty IPC with slice (#27708)
- Persist object\_store rebuild state in cache (#27707)
- Sort flag on GroupsType only applies to first element (#27684)
- Invalid unwrap\_unchecked when length isn't exact (#27685)
- Don't unwrap channel send in streaming join\_asof (#27688)
- Fix `merge_sorted` panic when List in frame (#27568)
- Put AsOf join buffered Morsels back the front of the deque if we cannot process them rn (#27658)
- Fix skip\_batches logic for NaN (#27673)
- Raise `TypeError` when calling `next()` directly on `GroupBy` objects (#27562)
- Data type comparison for extension types (#27632)
- Share last-morsel split budget across files in streaming multi-scan (#27630)
- Bytes scalars were not being broadcast in dataframe constructor (#27621)
- Reset the sort-options in `Series::is_sorted()` after row-encoding columns (#27614)
- Rayon deadlock with re-entrant io sources (#27600)
- Don't push negative-offset slices through `HConcat` (#27570)
- Logic error in streaming is\_empty (#27602)
- Fix incorrect CSE with large is\_in literal (#27575)
- AnonymousFunction can qualify as SQL aggregator (#26986)
- Fix CSPE panic in cloud (#27594)
- Set merge-join streaming node to `Finished` if its sending port is `Done` (#27572)
- Widen decimal precision on sum aggregation at runtime (#27579)
- Fix `str.to_time` was raising unnecessarily when input was all nulls (#27574)
- Prevent panic when switching from one extension dtype to another (#27566)
- Fix `DataFrame.write_database(..., if_table_exists="append", engine="adbc")` not handling missing tables correctly (#26913)
- Ensure `json_decode` doesn't fail for Date and Time string deserialization (#27554)
- Incorrect RUSTFLAGS passing in Makefile (#27555)
- Fix panic on reading IPC with 0-row compressed bitmap (#27551)
- Set HEAD\_RESPONSE\_SIZE\_ESTIMATE to 0 (#27548)
- Fix lazy concat horizontal didn'

_[Truncated at 4000 characters — full notes: https://github.com/pola-rs/polars/releases/tag/py-1.41.0]_