rename memmap -> memory_map as like Python (#15642)
pref(rust!, python): Unify sort with SortOptions and SortMultipleOptions (#15590)
Update the argument name from dims to dimensions in reshape (#15561)
Allow specifying Hive schema in read/scan_parquet (#15434)
Raise error when schema_overrides contains nonexistent column name (#15290)
Rename Chunk to RecordBatch (#15298)
Refactor AnyValue supertype logic (#15280)
Rename group_by_rolling to rolling and improve related error messages (#14765)
Rename ChunkedArray.try_apply to try_apply_values (#14947)
Rename parameter by to group_by in DataFrame.upsample/group_by_dynamic/rolling (#14840)

🚀 Performance improvements

Fix cross join batch size when one of the DataFrames is tiny (#14347)
Fix binview growable complexity O(n*m) -> O(n) (#15628)
Remove extra thread spawn from row group fetcher (#15626)
Use vertical parallelism if input is chunked for Filter,Select,WithColumns (#15608)
read_ipc memory usage tests, and writing fix (#15599)
Refactor CSV serialization to not go thorough AnyValue (#15576)
don't use dynamic dispatch in visitors (#15607)
Improve Bitmap construction performance (#15570)
join by row-encoding (#15559)
Replace std::thread spawn with tokio block_in_place (#15517)
speed up offset_by when a single offset is passed (#15493)
Avoid allocation in the hot path for struct JSON serialization (#15449)
avoid double-allocation in rolling_apply_agg_window (#15423)
Make LogicalPlan immutable (#15416)
Add non-order preserving variable row-encoding (#15414)
Use row-encoding for multiple key group by (#15392)
load bits one word at a time for BitmapIter (#15333)
Ipc exec multiple paths (#15040)
add SIMD support for if-then-else kernels (#15131)

✨ Enhancements

add Expr.dt.add_business_days and Series.dt.add_business_days (#15595)
Add str.head and str.tail (#14425)
Extended BytecodeParser to handle additional math functions, and imports from the global namespace (#15627)
Push down is_between expressions to Arrow (#15180)
add holidays argument to business_day_count (#15580)
change default to write parquet statistics (#15597)
Expressify to_integer (#15604)
Optimizer; remove double SORT and redundant projections (#15573)
Add null_on_oob parameter to expr.array.get (#15426)
support weekend argument in business_day_count (#15544)
Enable is_first/last_distinct for not nested non-numeric list (#15552)
Turn off cse if cache node found (#15554)
Tag concat list as elementwise (#15545)
Support list group-by of non numeric lists (#15540)
add business_day_count function (#15512)
Add SQL support for MEDIAN aggfunc (#15519)
Implement string, boolean and binary dtype in top_k (#15488)
Add SQL support for TRUNCATE TABLE command (#15513)
Add SQL support for GREATEST and LEAST (#15511)
Allow specifying Hive schema in read/scan_parquet (#15434)
Implements agg_list for NullChunked (#15439)
Supports explode_by_offsets for decimal (#15417)
Add null_on_oob parameter to expr.list.get (#15395)
CSV-writer escape carriage return (#15399)
Remove 'FileCacher' optimization (#15357)
check input type in entropy (#15351)
Implements arr.n_unique (#15296)
CSE don't scan share if predicate pushdown predicates don't match (#15328)
Remove cached nodes when finished (#15310)
Full plan CSE (#15264)
Add IR for expressions. (#15168)
Warn if map_elements is called without return_dtype specified (#15188)
Rename group_by_rolling to rolling and improve related error messages (#14765)
Rename ChunkedArray.try_apply to try_apply_values (#14947)
Implement strict AnyValue construction for temporal types (#15146)

🐞 Bug fixes

Return appropriate data type for time mean and median (#14471)
Support index upsampling (#13621)
Fix issue in write_excel that could lead to incorrect spanning range determination (#15631)
Output correct dtype for mean_horizontal on a single column (#15118)
Recompute RowIndex schema after projection pd (#15625)
Mean of boolean in streaming group_by incorrectly always gave NULL (#15616)
Include cloud creds in cache key (#15609)
Fix elementwise-apply if any input is AggregatedScalar (#15606)
Explode list should take validity into account (#15572)
use larger recursive stack in debug mode (#15593)
SQL interface "off-by-one' indexing error with GROUP BY clauses that use position ordinals (#15584)
Enable missing features in polars-time (#15558)
Handle quoted identifiers when registering CTEs in the SQL engine (#15564)
Decompress moved out of schema initialization (#15550)
Turn off cse if cache node found (#15554)
Resolve function names and prune all aliases. (#15522)
list.get should take validity into account (#15516)
block decimal in streaming (#15520)
group_by partitioned with literal Series panic (#15487)
Initialize validity for GroupsProxy::Slice windows (#15509)
Fix struct name resolving (#15507)
pow return type evaluation (#15506)
Allow selectors inside frame-level .filter() (#15445)
Don't prune alias in AnonymousFunction subtree (#15453)
Fix deadlock in async parquet scan (#15440)
datetime operations (e.g. .dt.year) were raising when null values were backed by out-of-range integers (#15420)
Ensure Binary -> Binview cast doesn't overflow the buffer size (#15408)
Don't prune alias in function subtree (#15406)
Return 0 for n_unique() in group-by context when group is empty (#15289)
Unset UpdateGroups after group-sensitive expression (#15400)
to_any_value should supports all LiteralValue type (#15387)
Hash failure combining hash of two numeric columns containing equal values (#15397)
Add FixedSizeBinary to arrow field conversion (#15389)
Conversion of expr_ir in partition fast path (#15388)
sort for series with unsupported dtype should raise instead of panic (#15385)
Return correct dtype for s.clear() when dtype is Object (#15315)
ensure first datapoint is always included in group_by_dynamic (#15312)
Non-exhaustive patterns: arrow-schema::DataType in polars-arrow (#15250)
use dynamic stacks for problematic recursive functions (#15355)
Raise error when schema_overrides contains nonexistent column name (#15290)
Fix cache dot visualization (#15311)
Properly propagate strict flag when constructing a Struct Series from any values (#15302)
ensure eq for BinaryViewArray checks all elements (#15268)
Raise when join projects name with suffix that doesn't exist (#15256)
fix kurtosis/skew (#15137)
Ensure ooc_start is set (#15255)
Fix bug where rolling operations were ignoring check_sorted in some cases (#15227)
Fix lazy schema for rle expression (#15248)
incorrect negative offset in multi-byte string slicing (#15140)
do not clamp negative offsets to start of array prematurely (#15242)
allow null index in list.get and array.get (#15239)
properly support nulls_last + descending (#15212)
Block rounding/truncating to negative durations (#15175)
Make parse_url work on windows with object_store (#15191)
divide by zero in download speed computation (#15182)

📖 Documentation

Add legacy CPU install instructions in user guide (#13676)
Various minor updates to User Guide's SQL intro section (#15557)
Add outer_coalesce join strategy in the user guide (#15405)
Improve docs for Series::new with AnyValue input (#15306)
Fix formatting in Series::from_any_values_and_dtype docs (#15244)
Correct the definition of an expression in the user guide (#14750)

📦 Build system

Fix a feature gate for lz4 compression in polars-parquet (#15565)
Update Rust toolchain (#15353)

🛠️ Other improvements

rename memmap -> memory_map as like Python (#15642)
fixup failing test due to offset deprecation in upsample (#15636)
use bound api (#15630)
Don't run streaming group-by in partitionable gb (#15611)
pref(rust!, python): Unify sort with SortOptions and SortMultipleOptions (#15590)
remove try_binary_elementwise_values (#15592)
remove raw pointers from visitors. (#15579)
rename to IR (#15571)
Update the argument name from dims to dimensions in reshape (#15561)
Rename ALogicalPlan to FullAccessIR (#15553)
Set up CodSpeed (#15537)
make dsl immutable and cheap to clone (#15394)
use recursive crate, add missing recursive tag (#15393)
Update CODEOWNERS (polars-sql) (#15384)
Update Rust toolchain (#15353)
Update CODEOWNERS (#15352)
remove try_apply_values (#15336)
always use non-legacy float_sum for mean (#15343)
remove legacy bitmap module (#15335)
More clippy in Makefile (#15340)
Rename Cache[count] to Cache[cache_hits] (#15300)
Cleanup file_caching optimization call (#15299)
Rename Chunk to RecordBatch (#15298)
Refactor AnyValue supertype logic (#15280)
reuse message parsing in IPC (#15265)
remove 'fast-projection' node (#15253)
cleanup column names in optimizer (#15252)
remove left_most_input_name from expr ir (#15251)
add AlignedBitmapSlice (#15171)
Refactor AnyValue construction for Categorical/Enum dtype (#15220)
Move ConsecutiveCountState into support module (#15186)
Run non-benchmark tests in benchmark workflow (#15207)
Add wrapping_abs to arithmetic kernel (#15210)
remove raw buffers from BinViewArray (#15206)
Enable RUST_BACKTRACE=1 in the CI test suite (#15204)
Rename parameter by to group_by in DataFrame.upsample/group_by_dynamic/rolling (#14840)
Set dual license for polars-arrow and polars-parquet (#15173)
remove parts of legacy bit_util (#15169)
remove legacy arrow compute (#15164)

Thank you to all our contributors for making this release possible! @CanglongCl, @ChayimFriedman2, @Fokko, @JamesCE2001, @MarcoGorelli, @NedJWestern, @Sol-Hee, @TrevorWinstral, @alexander-beedie, @braaannigan, @c-peters, @cmdlineluser, @cojmeister, @deanm0000, @dependabot, @dependabot[bot], @douglas-raillard-arm, @eitsupi, @filabrazilska, @henryharbeck, @i-aki-y, @itamarst, @kszlim, @leoforney, @mbuhidar, @mcrumiller, @mickvangelderen, @nameexhaustion, @orlp, @ozgrakkurt, @petrosbar, @reswqa, @ritchie46, @rob-sil, @sportfloh, @stinodego, @thomaslin2020 and @yutannihilation