⚠️ Deprecations

• Deprecate retries=n in favor of storage_options={"max_retries": n} (#26155)

🚀 Performance improvements

• Enable zero-copy object_store put upload for IPC sink (#26288)
• Resolve file schema's and metadata concurrently (#26325)
• Run elementwise CSEE for the streaming engine (#26278)
• Disable morsel splitting for fast-count on streaming engine (#26245)
• Implement streaming decompression for scan_ndjson and scan_lines (#26200)
• Improve string slicing performance (#26206)
• Refactor scan_delta to use python dataset interface (#26190)
• Add dedicated kernel for group-by arg_max/arg_min (#26093)
• Add streaming merge-join (#25964)
• Generalize Bitmap::new_zeroed opt for Buffer::zeroed (#26142)
• Reduce fs stat calls in path expansion (#26173)
• Lower streaming group_by n_unique to unique().len() (#26109)

✨ Enhancements

• Avoid OOM for scan_ndjson and scan_lines if input is compressed and negative slice (#26396)
• Support annoymous agg in-mem (#26376)
• Add unstable arrow_schema parameter to sink_parquet (#26323)
• Improve error message formatting for structs (#26349)
• Remove parquet field overwrites (#26236)
• Enable zero-copy object_store put upload for IPC sink (#26288)
• Improved disambiguation for qualified wildcard columns in SQL projections (#26301)
• Expose upload_concurrency through env var (#26263)
• Allow quantile to compute multiple quantiles at once (#25516)
• Allow empty LazyFrame in LazyFrame.group_by(...).map_groups (#26275)
• Use delta file statistics for batch predicate pushdown (#26242)
• Add streaming UnorderedUnion (#26240)
• Implement compression support for sink_ndjson (#26212)
• Add unstable record batch statistics flags to {sink/scan}_ipc (#26254)
• Support CSE for python UDFs on the same address (#26253)
• Cloud retry/backoff configuration via storage_options (#26204)
• Use same sort order for expanded paths across local / cloud / directory / glob (#26191)
• Add streaming merge-join (#25964)
• Serialize optimization flags for cloud plan (#26168)
• Add compression support to write_csv and sink_csv (#26111)
• Add scan_lines (#26112)
• Support regex in str.split (#26060)
• Add unstable IPC Statistics read/write to scan_ipc/sink_ipc (#26079)
• Add unstable height parameter to DataFrame/LazyFrame (#26014)
• Remove old partition sink API (#26100)
• Expose ArrowStreamExportable on python collect batches iterator (#26074)
• Add nulls support for all rolling_by operations (#26081)

🐞 Bug fixes

• Correct off-by-one in RLE row counting for nullable dictionary-encoded columns (#26411)
• Support very large integers in env var limits (#26399)
• Fix PlPath panic from incorrect slicing of UTF8 boundaries (#26389)
• Fix Float dtype for spearman correlation (#26392)
• Fix optimizer panic in right joins with type coercion (#26365)
• Don't serialize retry config from local environment vars (#26289)
• Fix PartitionBy with scalar key expressions and diff() (#26370)
• Add {Float16, Float32} -> Float32 lossless upcast (#26373)
• Fix panic using with_columns and collect_all (#26366)
• Add multi-page support for writing dictionary-encoded Parquet columns (#26360)
• Ensure slice advancement when skipping non-inlinable values in is_in with inlinable needles (#26361)
• Pin xlsx2csv version temporarily (#26352)
• Bugs in ViewArray total_bytes_len (#26328)
• Overflow in i128::abs in Decimal fits check (#26341)
• Make Expr.hash on Categorical mapping-independent (#26340)
• Clone shared GroupBy node before mutation in physical plan creation (#26327)
• Fixed "sheet_name" typing for read_ods and read_excel (#26317)
• Improve Polars dtype inference from Python Union typing (#26303)
• Consider the "current location" of an item when computing rolling_rank_by (#26287)
• Reset is_count_star flag between queries in collect_all (#26256)
• Fix incorrect is_between filter on scan_parquet (#26284)
• Make polars compatible with ty (#26270)
• Lower AnonymousStreamingAgg in group-by as aggregate (#26258)
• Avoid overflow in pl.duration scalar arguments case (#26213)
• Broadcast arr.get on single array with multiple indices (#26219)
• Fix panic on CSPE with sorts (#26231)
• Eager DataFrame.slice with negative offset and length=None (#26215)
• Use correct schema side for streaming merge join lowering (#26218)
• Overflow panic in scan_csv with multiple files and skip_rows + n_rows larger than total row count (#26128)
• Respect allow_object flag after cache (#26196)
• Raise error on non-elementwise PartitionBy keys (#26194)
• Allow ordered categorical dictionary in scan_parquet (#26180)
• Allow excess bytes on IPC bitmap compressed length (#26176)

📖 Documentation

• Fix Expr.get referencing incorrect dtype for index parameter (#26364)
• Fix Expr.quantile formatting (#26351)
• Drop sphinx-llms-txt extension (#26285)
• Remove deprecated cublet_id (#26260)
• Update for new release (#26255)
• Update MCP server section with new URL (#26241)
• Fix unmatched paren and punctuation in pandas migration guide (#26251)
• Add observatory database_path to docs (#26201)
• Note plugins in Python user-defined functions (#26138)

📦 Build system

• Address remaining Python 3.14 issues with make requirements-all (#26195)
• Address a macOS-specific compile issue (#26172)

🛠️ Other improvements

• Ensure local doctests skip from_torch if module not installed (#26405)
• Change linked timezones in test suite to canonical timezones (#26310)
• Implement various deprecations (#26314)
• Rename Operator::Divide to RustDivide (#26339)
• Properly disable the Pyodide tests (#26382)
• Remove unused field (#26367)
• Fix runtime nesting (#26359)
• Remove xlsx2csv dependency pin (#26355)
• Use outer runtime if exists in to_alp (#26353)
• Make CategoricalMapping::new pub(crate) to avoid misuse (#26308)
• Clarify IPC buffer read limit/length paramter (#26334)
• Add dtype test coverage for delta predicate filter (#26291)
• Add AI policy (#26286)
• Unpin "pandas<3" in dev dependencies (#26249)
• Remove all non CSV fast-count paths (#26233)
• Pin pandas to 2.x for now (#26221)
• Remove unnecessary xfail (#26199)
• Ensure optimization flag modification happens local (#26185)
• Simplify IcebergDataset (#26165)
• Reorganize unit tests into logical subdirectories (#26149)
• Lint leftover fixme (#26122)
• Improve backtrace for POLARS_PANIC_ON_ERR (#26125)
• Fix Python docs build (#26117)
• Disable unused-ignore mypy lint (#26110)
• Ignore mypy warning (#26105)
• Raise error on file://hostname/path (#26061)
• Disable debug info for docs workflow (#26086)
• Update docs for next polars cloud release (#26091)
• Support Python 3.14 in dev environment (#26073)

Thank you to all our contributors for making this release possible! @Atarust, @EndPositive, @Kevin-Patyk, @LeeviLindgren, @MarcoGorelli, @Matt711, @MrAttoAttoAtto, @Voultapher, @WaffleLapkin, @agossard, @alex-gregory-ds, @alexander-beedie, @azimafroozeh, @bayoumi17m, @c-peters, @carnarez, @dependabot[bot], @dsprenkels, @hallmason17, @hamdanal, @ion-elgreco, @kdn36, @lun3x, @mcrumiller, @nameexhaustion, @orlp, @qxzcode, @r-brink, @ritchie46, @sweb and dependabot[bot]