Rename Utf8 data type to String (#13224)
Rename set_at_idx to scatter (#12687)
Preserve left and right join keys in outer joins (#12963)
Implement dtype parameter for int_range on Rust side (#12940)
Update Expr.count to ignore null values by default (#12934)
Change value_counts resulting column name from counts to count (#12506)
Change default join behavior with regard to nulls, add join_nulls parameter to keep existing behavior (#12840)
Smaller integer data types for datetime components (#12070)
Fix NaN ordering to make NaNs compare greater than any other float, and equal to themselves (#12721)
Rename frame_equal/series_equal to equals (#12663)
Rename not_ expression to not on the Rust side (#12587)
Rename str.json_extract to str.json_decode (#12586)
Rename DataFrame column index methods (#12542)

🚀 Performance improvements

optimize set bit count (#13317)
speed up .dt.truncate for large numbers of years (#13310)
don't eagerly evaluate error branches (#13311)
don't needlessly allocate validity in concat/rechunk (#13288)
add fast path to count_bits_set_by_offsets (#13253)
make .dt.truncate('*mo') more than 3x faster (#13192)
ensure single expression evaluation for replace (#13147)
Elide allocation in outer join materialization (#12992)
Ensure we reduce for any/all_horizontal (#12976)
Add fast paths for UTC in truncate (#12965)
Improve rolling_median algorithm (#12704)
Use fast path for non-null data in new SQL-like null matching (#12874)
improve merge_local_rhs_categorical traversal (#12660)
make values_size estimate correct for sliced arrays (#12658)
improve parquet utf8 validation (#12655)
parquet pre-allocate buffer in binary plain encode (#12652)
optimize dict binary decoding in parquet (#12648)
ensure we only check the values within bounds (#12633)
parquet; elide recursion in hot path (#12625)
improve cov/corr algorithm (#12590)
apply left side predicate pushdown also to right side on semi join (#12565)
ensure streaming parquet download remains concurrent ~7x (#12552)
speed up parquet download of streaming engine (#12544)

✨ Enhancements

support negative indices in gather in group_by context (#13373)
support negative indexing in gather (select context) (#13343)
support min_periods for temporal rolling aggregations (#13342)
support REGEXP and RLIKE pattern matching in SQL engine (#13359)
gracefully handle panics in plugins (#13329)
Implement unique/n_unique/unique_counts/is_unique/is_duplicated for Null series (#13307)
support common variant spelling STDEV in the SQL engine (in addition to STDDEV) (#13303)
change doc links to new url docs.pola.rs (#13290)
support horizontal concatenation of LazyFrames (#13139)
Impl serde for array dtype (#13168)
dispatch strict_cast via cast (#13255)
Impl any/all for array type (#13250)
add cancellable queries (#13178)
add offset parameter to gather_every (#13156)
Support Array dtype AnyValue Series construction (#12817)
Allow step parameter in int_ranges to take an expression (#13148)
Implement count for DataFrame/LazyFrame (#13153)
Move from GA to more privacy friendly framework (#13155)
Rename set_at_idx to scatter (#12687)
prune all/any_horizontals with single inputs (#13146)
ensure we get cleaner logical plans with any/all_horizontal (#13144)
Add str.contains_any and str.replace_many (Aho-Corasick algorithms) (#13073)
Auto-infer credentials from .aws folder (#13062)
Support private cloud S3 storage in scan_parquet (#13060)
Allow order operators (<,>,>=,<=) on Enum types (#12982)
Reimplement replace expression on the Rust side (#13002)
Use tokio semaphore for concurrency handling (#13026)
Improve and expressify hist (#13014)
Preserve left and right join keys in outer joins (#12963)
Allow end before start in date/time_range (#12964)
Implement group-tuples for Null dtype (#12975)
Implement dtype parameter for int_range on Rust side (#12940)
Cast to an enum from int (#12954)
Move categorical ordering into dtype (#12911)
Update Expr.count to ignore null values by default (#12934)
Enable partial predicate pushdown past window expressions (#12710)
Add str.reverse (#12878)
Change value_counts resulting column name from counts to count (#12506)
Implement std and var for Duration columns (#12865)
Change default join behavior with regard to nulls, add join_nulls parameter to keep existing behavior (#12840)
Preserve base dtype when raising to UInt power (#10446)
Smaller integer data types for datetime components (#12070)
Support SQL subqueries for JOIN and FROM (#12819)
parquet support required deltabyte encoding (#12836)
Add new Enum categorical data type which allows a fixed set of categories (#11822)
support nested null in vstack/append/extend/concat (#12771)
Improve error messages on attempted Arrow conversions involving incompatible/unknown dtypes (#12421)
determine mode parallelism depending on current tasks (#12764)
enable slice push down past with_columns (#12742)
implement From<LazyGroupBy> for LazyFrame (#12562)
Rename frame_equal/series_equal to equals (#12663)
Join operations on local categoricals (#12657)
use RLE_DICTIONARY for integers in parquet (#12647)
Add configuration option for where Polars spills to disk (#12595)
implement RLE_DICT encoding for utf8/binary columns (reduced parquet file size) (#12623)
implement 'DeltaByteArray' decoding for parquet (#12602)
warn if by column is not sorted in rolling aggregations (as opposed to raising), add warn_if_unsorted argument (#12398)
struct -> json encoding expression (#12583)
Implement support for multi-character comments in read_csv (#12519)
Implement LazyFrame.sink_ndjson (#10786)
improve concurrency parameters (#12567)
Adds sink_ipc_cloud (#12556)
Adds sink_ipc_cloud (#11008)
In explain(), rename PIPELINE to STREAMING so it's clearer what it means (#12547)

🐞 Bug fixes

range/ranges output name should follow lhs rule (#13369)
updated Display trait for enum categoricals (#13331)
nested dtypes: export logical type in plugins (#13325)
fix invalid dtype setting in array (#13327)
fix csv parser error when commented-out rows precede the header row (#13318)
invalid schema outer join after projection pd (#13315)
invalid predicate optimization (#13313)
Account for null values in categorical unique/n_unique (#13308)
fix schema when subtracting (#13309)
broadcasting of unit LHS in string operations (#12737)
casting list/arr to arr/list shouldn't convert chunks to logical type (#13259)
sorting categorical lexically bugs on null values (#13271)
improve replace on categoricals (#13223)
round trip to JSON and back should preserve Enum type (#13267)
enable and fix SIMD in polars-compute (#13251)
match_chunks shouldn't change the dtype (#13222)
sink_csv deadlock (#13239)
is_in operator for categoricals (#13205)
Better handle mismatched dtypes in replace (#13213)
Fix replace fast path by casting old input to the right data type (#13176)
ndjson nested null schema inference (#13206)
slice for NullChunked no longer force single chunk (#13174)
don't cast to unknown dtypes (#13197)
Allow casting nullable list to array (#13196)
maintain old join behavior in window expression (#13179)
Fix comparison of categoricals (#13137)
Use the name of the leftmost expression in horizontal operations (#13143)
any_value should supports cast to boolean (#13125)
Update offsets of null value correctly for all from_iter_xxx_trusted_len (#13132)
fix neq for series cmp str (#13128)
fix category list builder append series with multiple chunks (#13116)
repeat_by should not raise if by contains nulls (#13105)
[csv] raise on single quote char (#13104)
Raise if scan zstd compressed csv file (#13102)
Don't check map length if input is literal (#13098)
use FunctionExpr's scalar return type for is_in (#13091)
rolling_quantile can get incorrect state (#13088)
Fix off-by-one error in quantile(method="nearest") (#13058)
Fix incorrect schema inference on nested columns (#13057)
Don't raise for datetime_range if starting on ambiguous datetime and earliest was specified (#13050)
add cast safety to literals (#12983)
Parse json_decode per max buffer length (#13029)
Parse 00:00 time zone as UTC (#13034)
Fix timeout errors in concurrent downloads (#13023)
Fix SQL substring indexing (#13016)
Allow broadcasting in ranges (#11900)
Prevent deadlock in sink_csv (#12991)
Don't get mutable if buffer is sliced (#12979)
Dataframes with Decimal columns cannot be pickled (#12955)
Fix truncate when truncating by multiple weeks (#12948)
Fix segfault / memory corruption after plugins return Err result (#12953)
Don't panic when ambiguous parameter is not Utf8 (#12913)
don't panic on empty df in merge_sort (#12923)
Patch rolling_var/rolling_std numerical stability (#12909)
Fix incorrect Int16 min/max due to incorrect SIMD mask construction (#12908)
Fix OOB error in list set operations on empty frame (#12845)
Fix repr of Expr.gather (which was still showing deprecated take) (#12864)
Fix nan_min/max incorrectly aggregating chunks with addition (#12848)
write only one dict page per row rowgroup (#12831)
incorrect values from parquet RLE decoding (#12818)
Handle aggregation for all-NaN groups in group_by (#12304)
Use total float ordering in is_in (#12800)
Fix NaN ordering to make NaNs compare greater than any other float, and equal to themselves (#12721)
don't use streaming engine if aggregate is unknown (#12769)
hold align_chunks_invariant (#12738)
allow leading zero and plus in integer parsing (#12744)
csv lines iter, always return remainder (#12739)
fix oob in set operations (#12736)
undo regression in ability to read certain parquet files (#12731)
corr return nan if denominator is invalid (#12708)
parquet decimal statistics and schema (#12705)
support append/extend with null series (#11824) (#12686)
fix carrying over infinity into other windows (#12685)
json null inference (#12677)
cov/corr respect f32 type (#12676)
fix ternary zip_with null broadcast (#12668)
support negative slice on eager frame (#12644)
fix concurrency budget assertion (#12641)
fix oob in set operations (#12640)
Rename not_ expression to not on the Rust side (#12587)
panic reading parquet nested struct column (#12614)
features: performant,lazy,random (#12600)
error when invalid list to array is given (#12584)
parquet: do not extend existing nested that is already complete (#12569)
accidental panic if predicate selects no files (#12575)
fix lazy parquet slice with nested columns (#12558)
ensure stats-evalutor exists (#12566)
list schema of list eval (#12563)
ensure concurrency budget never locks (#12555)
Fix lazy schema for group_by_dynamic and rolling (#12551)
address overflow on vec capacity calculation for int_ranges with negative step (#12548)

🛠️ Other improvements

Update CODEOWNERS (#13292)
Change base url of docs/guide to docs.pola.rs (#13281)
Add note about Rust examples versioning in user guide (#13280)
split-up file_sink module (#13256)
Rename Utf8 data type to String (#13224)
update rustc (#13219)
fix horizontal concatenation documentation (#13141)
Set minimum version for bytemuck to 1.11 (#13191)
bump sysinfo from 0.29.11 to 0.30.0 (#13188)
Remove polars-algo reference in Cargo.toml (#13187)
Use the name of the leftmost expression in horizontal operations (#13143)
make pre_agg generic (#13150)
move StaticArray to polars-arrow (#13106)
ensure we get cleaner logical plans with any/all_horizontal (#13144)
Update auto_explode param name to returns_scalar (#13119)
don't compile polars-ops by default (#13100)
update user-defined-functions for 0.19.x (#13071)
Linting updates (#13069)
take pl.concat out of StringCache context manager in "mismatched string cache" error message (#13076)
add Enum to dtype list (#13080)
further use TotalOrd (#13046)
Minor typo fix (#13003)
use new MinMax kernels (#12961)
Refer to arrow crate unambiguously from polars-parquet (#12939)
Fix issue with docs for group_by_dynamic (#12906)
Fix failing tests (#12859)
Update make check to only check polars crate (#12834)
apply TotalOrd in more places (#12810)
Use latest atoi_simd release (#12748)
simplify rolling_median update (#12745)
move nan_cmp and IsFloat to polars_utils (#12691)
remove utf8 code in favor of binary (#12604)
update custom allocator instructions to include macOS (#12593)
Rename str.json_extract to str.json_decode (#12586)
parquet refactors (#12574)
convert all recursive parquet deserialize to iterative (#12560)
Rename DataFrame column index methods (#12542)

Thank you to all our contributors for making this release possible! @0siride, @MarcoGorelli, @Object905, @PierreAttard, @Qqwy, @RoDmitry, @SeanTroyUWO, @TNieuwdorp, @Yerachmiel-Feltzman, @adamreeve, @alexander-beedie, @c-peters, @cardoso, @cjfuller, @dependabot, @dependabot[bot], @dmitrybugakov, @eitsupi, @fernandocast, @gab23r, @ion-elgreco, @itamarst, @jankislinger, @jeroenboeye, @kszlim, @mcrumiller, @nameexhaustion, @oli-clive-griffin, @orlp, @paddymul, @petrosbar, @r-brink, @rancomp, @reswqa, @ritchie46, @rob-sil, @robvanmieghem, @romanovacca, @stinodego, @tkarabela, @uchiiii and @xuestrange