💥 Unstable Breaking changes

These API's were marked unstable and are allowed to change.

• Use Altair in DataFrame.plot (#17995)

🚀 Performance improvements

• Parquet do not copy uncompressed pages (#18441)
• Several large parquet optimizations (#18437)
• Batch Plain Parquet UTF-8 verification (#18397)
• Partition metadata for parquet statistic loading (#18343)
• Fix accidental quadratic parquet metadata (#18327)
• Lazy decompress Parquet pages (#18326)
• Don't rechunk aligned chunks in owned_binary_chunk_align (#18314)
• Batch DELTA_LENGTH_BYTE_ARRAY decoding (#18299)
• Slice pushdown for SimpleProjection (#18296)
• Use direct path for time/timedelta literals (#18223)
• Speedup ndjson reader ~40% (#18197)
• Skip parquet page when unneeded (#18192)

✨ Enhancements

• Use Altair in DataFrame.plot (#17995)
• Allow mapping as syntactic sugar in str.replace_many (#18214)
• Respect input time zone if input is pandas Timestamp (#18346)
• Improve Schema and DataType interop with Python types (#18308)
• Add POLARS_BACKTRACE_IN_ERR for debugging (#18333)
• IR serde (#18298)
• Improve decimal_comma error message (#18269)
• Support pre-signed URLs for cloud scan (#18274)
• Support the most recent version of "duckdb_engine" connections via read_database (#18277)
• Support empty structs (#18249)
• Allow float in interpolate_by by column (#18015)
• Make show_versions more responsive (#18208)

🐞 Bug fixes

• Enable CSE in eager if struct are expanded (#18426)
• Treat explode as gather (#18431)
• Parquet nested values that span several pages (#18407)
• Support reading empty parquet files (#18392)
• Recurse on map field during type conversion (#15075)
• Allow search_sorted on boolean series (#18387)
• Mark Expr.(lower|upper)_bound as returning scalar (#18383)
• Fix compressed ndjson row count (#18371)
• Use correct column names when there are no value columns in unpivot (#18340)
• Parquet several smaller issues (#18325)
• Fix group-by slice on all keys (#18324)
• Compute joint null mask before calling rolling corr/cov stats (#18246)
• Several scan_parquet(parallel='prefiltered') problems (#18278)
• Json feature flag missing imports (#18305)
• Check groups in group-by filter (#18300)
• Parquet delta encoding for 0-bitwidth miniblocks (#18289)
• Arguments for upsample only have to be sorted within groups (#18264)
• Use appropriate bins in hist when bin_count specified (#16942)
• Raise suitable error on unsupported SQL set op syntax (#18205)
• Fix invalid state due to cached IR (#18262)
• Fix failed AWS credential load from '~/.aws/credentials' due to formatting (#18259)
• Fix panic streaming parquet scan from cloud with slice (#18202)
• Consistently round half-way points down in dt.round (#18245)
• Fix duplicate column output and panic for include_file_paths (#18255)
• Fix unit null rank (#18252)
• Use physical for row-encoding (#18251)
• Convert date and datetime in literal construction (#16018)
• Fix gather str as lit (#18207)

📖 Documentation

• Add date_range and datetime_ranges examples without eager=True (#18379)
• Fix incorrect comments in group_by_dynamic (#18415)
• Alphabetise methods in Python API reference (#18380)
• Document POLARS_BACKTRACE_IN_ERR env var (#18354)
• Add missing aggregation entries (#18334) (#18341)
• Add missing Series methods to API reference (#18312)
• Document DataFrame.__getitem__ and Series.__getitem__ (#18309)
• Fix typos and add see also links to struct name expressions (#18282)
• Improve decimal_comma error message (#18269)
• Clarify coalesce behaviour in join_asof (#18273)
• Add note to Expr.shuffle differentiating from df method (#18266)
• Improve formatting and consistency of various docstrings (#18237)
• Add missing "Parameters" section to bin.size expr docstring (#18222)
• Fix column name output in example of DataFrame.map_rows (#18227)

📦 Build system

• Bump Rust toolchain to nightly-2024-08-26 (#18370)

🛠️ Other improvements

• Address spurious hypothesis test failure (#18434)
• Turn all Binary/Utf8 into BinaryView/Utf8View in Parquet (#18331)
• Fix the required version of rust in README.md (#18357)
• Remove unused Parquet indexes (#18329)
• Deprecate serialize json for LazyFrame (#18283)
• Don't add sink node to cloud query (#18280)
• Split py-polars crate (#18204)
• Fix test for new deltalake release (#18211)
• Update the required version of rust in README.md (#18203)
• Fix version bifurcation for test_read_database_cx_credentials (#18220)
• Use or_else for raising (#18206)
• Remove unused Parquet source files (#18193)

Thank you to all our contributors for making this release possible! @BartSchuurmans, @ChayimFriedman2, @MarcoGorelli, @StepfenShawn, @agossard, @alexander-beedie, @cgbur, @coastalwhite, @corwinjoy, @deanm0000, @henryharbeck, @ion-elgreco, @jqnatividad, @krasnobaev, @liufeimath, @markxwang, @mcrumiller, @nameexhaustion, @orlp, @ritchie46, @stinodego, @sunadase, @thomascamminady and @wence-