Polars 1.21.0

🚀 Performance improvements

• Use BitmapBuilder in yet more places (#20868)
• Make an owned version of append (#20800)
• Use BitmapBuilder in a lot more places (#20776)

✨ Enhancements

• Stabilize methods/functions (#20850)
• Add linear_space (#20678)
• Improve string → temporal parsing in read_excel and read_ods (#20845)
• Implement df.unique() on new-streaming engine (#20875)
• Experimental credential provider support for Delta read/scan/write (#20842)
• Allow column expressions in DataFrame unnest (#20846)
• Auto-initialize Python credential providers in more cases (#20843)
• Add unique operations for Decimal dtype (#20855)
• Add NDJson sink for the new streaming engine (#20805)
• Support nested keys in window functions (#20837)
• Add CSV sink for the new streaming engine (#20804)
• Periodically check python signals ('CTRL-C' handling) (#20826)
• Experimental unity catalog client (#20798)
• Support cumulative aggregations for Decimal dtype (#20802)
• Account for SurrealDB Python API updates (handle both SurrealDB and AsyncSurrealDB classes) in read_database (#20799)
• Drop nest-asyncio in favor of custom logic (#20793)
• Improve window function caching strategy (#20791)
• Support lakefs:// URI for delta scanner (#20757)
• Additional support for loading numpy.float16 values (as Float32) (#20769)

🐞 Bug fixes

• Warn if asof keys not sorted (#20887)
• Ensure explicit values given to column_widths override autofit in write_excel (#20893)
• Avoid name collisions and panicking in object conversion (#20890)
• Incorrect scale used in log and exp for Decimal type (#20888)
• Don't deep clone manuallydrop in GroupsPosition (#20886)
• Fix DuplicateError when selecting columns after join_where or cross join + filter (#20865)
• Incorrect Decimal value for fill_null(strategy="one") (#20844)
• Fix one edge case (out of many) of int128 literals not working (#20830)
• Add height check to frame-level row indexing when key is int (#20778)
• Remove assert that panics on group_by followed by head(n), where n is larger then the frame height (#20819)
• Selectors should raise on + between themselves (#20825)
• Fix panic InvalidHeaderValue scanning from S3 on Windows (#20820)
• Fix clip for Decimal returning wrong values (#20814)
• Incorrect height from slicing after projecting only the file path column (#20817)
• Shift mask when skipping Bitpacked values in Parquet (#20810)
• Error instead of truncate if length mismatch for several str functions (#20781)
• Support cumulative aggregations for Decimal dtype (#20802)
• Allow is_in values to be given as custom Collection (#20801)
• Propagate null instead of panicking in pl.repeat_by() (#20787)
• Do not print sensitive information to output on POLARS_VERBOSE (#20797)
• Ignore file cache allocation error if fallocate() is not permitted (#20796)
• Incorrect logic in assert_series_equal for infinities (#20763)

📖 Documentation

• Update source URL for legislators-historical.csv (#20858)
• Update ML part of ecosystem user guide page (#20596)

🛠️ Other improvements

• Disable 'catalog' in build (#20897)
• Implement negative slice for new streaming IPC (#20866)
• Debloat Series bitops (#20873)
• Reduce python map bloat (#20871)
• Remove todo and test restriction for new-streaming (#20861)
• Dispatch to the in-mem engine for AExpr::Gather (#20862)
• Dispatch to the in-memory engine for multifile sources (#20860)
• Add tests for open issues (#20857)
• Mark 'register_startup' as unsafe (#20841)
• Reduce mode bloat (#20839)
• Rename ContainsMany to ContainsAny (#20785)
• Unpin NumPy in type checking workflow (#20792)
• Add various tests (#20768)
• Small drive-by's (#20772)
• Touch the upload probe for the remote benchmark (#20767)

Thank you to all our contributors for making this release possible! @alexander-beedie, @arnabanimesh, @braaannigan, @burakemir, @coastalwhite, @etiennebacher, @ion-elgreco, @itamarst, @lukemanley, @mcrumiller, @nameexhaustion, @orlp, @ritchie46 and @stinodego