polars-time

This Releases' DSL matches Python 1.43.2.

🚀 Performance improvements

• Pushdown len() to concat/union inputs (#28570)
• Optimize not(bool_f) to not_bool_f (#28474)
• Split multiplexers that directly scan from in-memory DataFrame (#28376)
• Make DNS cache global (#28352)
• Do not remove cache if predicates not pushed to all inputs (#28341)
• Environment variable for logging slow DNS lookup (#28211)
• Pre-partition on left, right and semi joins on hive partitioned data (#28374)
• Rewrite inner joins on hive partitioned data to a union of partitions filtered joins (#28327)
• Tighten redundant comparisons and propagate filter constraints (#27999)
• Canonicalize predicates (#28212)
• Remove excess memory copy in streaming IPC sink (#28141)
• Parallelize scan_iceberg resolve (#28168)
• Chunk-aware morsel splitting on single-file IO sink (#27950)
• Don't allocate for full_null() with small lengths (#28181)
• Use monotonic deque for rolling min_by/max_by (O(n)) (#27436)
• Add a sampled resolve mode for multi-file parquet metadata (#28111)
• Speed up small dtype series sums with a upcast sum kernel (#27958)
• Don't block on path expansion (#28073)
• Add bytes-based concurrency control for cloud IO (#27924)
• Stop flushing multiplexer on phase change (#28013)
• Prevent empty chunks from triggering copy in rechunk (#27953)
• Improve performance of struct unnest inside list eval on streaming (#27905)

✨ Enhancements

• Add struct.drop() (#28666)
• Improve error message when CSV name de-duplication fails (#28658)
• Always keep first metadata per source for Parquet (#28661)
• Improve plan-time row estimates for multi-file parquet scans (#28380)
• Serialize and deserialize SinkTypeIR::Partitioned (#28112)
• Add infer_schema_files parameter to scan_csv (#28440)
• Support reading IEEE 754 total order Parquet column order (#27896)
• Expose more Expr nodes for cudf_polars (pt 2) (#28404)
• Allow callback sinks on cloud (#28458)
• Pre-partition group-by on hive keys (#28444)
• Add ewm_sum and ewm_sum_by #28151 (#28215)
• Serve stale records from object_store DNS cache (#28256)
• Expose more expr nodes for cudf-polars (#28117)
• Make partition_hive an opt flag (#28345)
• When displaying IRExprs, only add parentheses when needed for disambiguation (#28319)
• Show only differing dtypes in assert_frame_equal error (#27816)
• Add Clone to SpillFrame/Token (#28302)
• Add Series.degrees/radians and clarify trig functions use radians (#22961)
• Merge sorted with multikey (#28067)
• Add list expression which consistently packs elements together into new List type (#27990)
• Construct pyarrow predicates via PyO3 instead of eval str (#27271)
• Optimize joins with redundant equi-join keys (#28017)
• Implement missing datetime options for CastColumnsPolicy (#28084)
• Add Expr.cat.to and Expr.cat.physical (#28096)
• Add POLARS_OOC_DISK_BUDGET_MB (#28045)
• Close ResourceWarning leaks in database tests (#28066)
• Expose IRFunctionExpr::Fused in the python node visitor (#27889)
• Deprecate casts from string to temporal dtypes (#28056)
• Add naive out-of-core spilling to Polars (#27998)
• Add experimental strict mode (#28023)
• Optimize non-negative len and null_count comparisons (#28002)
• Optimize len and null_count comparisons (#27727)
• Support SQL's implicit JOIN syntax (#27890)
• Sample from bivariate distribution for spill context Thompson sampling (#27973)
• Add Expr.is_sorted (#26708)
• Add suggestions in wrong api usage or mismatched column names (#27954)
• Add external object_store support for non-native schemes (#27871)
• Skip Delta files and parquet row groups using per-field struct statistics (#27887)
• Add re-registration of OOC SpillTokens (#27909)
• Improve IR sortedness detection for with_row_index and explode (#27875)
• Add DataFrame.is_sorted() (#27870)

🐞 Bug fixes

• Don't hand IO plugins a predicate they cannot evaluate (#28643)
• Don't hang or crash on sqrt/cbrt/pct_change/ewm_* with a Struct column (#28696)
• Raise on overflow in Decimal sum instead of silently wrapping (#28688)
• Preserve nulls when importing Arrow maps (#28680)
• Propagate null by column values in rolling_*_by (#27367)
• Fix self-referencing field in struct.with_fields with over (#28678)
• Fix Arrow buffer offset for Utf8 and Binary (#28662)
• Clamp group-by slice offset (#28579)
• Ensure categorical fill_null(strategy="min"/"max") uses lexical min/max (#28636)
• Release the GIL while resolving the schema in __arrow_c_stream__ (#28642)
• Fix data corruption on Series from nested Arrow LargeList (#28632)
• Properly propagate enum metadata for iceberg column mapping (#28580)
• Correctly write parquet field IDs for enums and categoricals (#28581)
• Fix arrow C interop binview offset (#28623)
• Fix duplicate hive values in hive pre-partition rewrite (#28621)
• Double-counted offset for Arrow export of sliced Series(Array) (#28602)
• Struct/List/Array equality handling in sort and join (#28601)
• Use try_new in StructArray construction in polars-json (#27489)
• Raise ComputeError instead of panicking in repeat_by when output exceeds IdxSize::MAX (#27892)
• Run type coercion pass on pivot's internally generated group_by (#27897)
• More careful slice pushdown into joins (#28578)
• Preserve ordering in sliced unions (#28576)
• Drop input sortedness when casting to a string (#28574)
• Clear sortedness flags in StringChunked substring kernels (#28573)
• Bad mask handling when reading optional parquet column (#28547)
• Any operation on Unknown(Int) and Unknown(Float) should result in Unknown(Float) (#28545)
• Flip nulls_last after Expr.reverse() (#28572)
• Fix high blocking thread use in sink_parquet with async local path (#28543)
• Serialize LazyFrames backed by bytes (#28568)
• Release GIL in SQLContext.execute() (#28549)
• Propagate nulls_last in function_expr_sortedness (#28544)
• Incorrect slicing when a join requires sorting (#28541)
• Fix panic on self join of scan_delta / scan_iceberg (#28468)
• Decrement ParkGroup worker count when worker exits (#28492)
• Add missing Send bounds in Connector (#28497)
• Fix UB on first/last_non_null with empty chunk (#28495)
• Do not CSE non-column height expr on streaming engine (#28480)
• Propagate adjusted sortedness through Gather (#28493)
• Deduplicate the expression equality checks (#28483)
• Address 3VL issue with SQL NOT IN interaction with NULL values and joins (#28484)
• Use total comparison in Expr literal values (#28482)
• Ensure SQL SUM and CORR aggregates return NULL for all-null inputs, add TOTAL (#28475)
• Share null_count_dtype helper between Delta and Iceberg, fixing SchemaError (#28479)
• Remove non-output columns from the equi-join and semi/anti-join operators (#28446)
• Fix dropped slice on multiple unions (#28477)
• Fix in-memory engine incorrect slice on maintain order join (#28478)
• Check join schema by position (#28455)
• Block predicate pushdown past overwritten window keys (#28429)
• Avoid panic when union slice skips all rows (#28420)
• Solve panic in dt.replace when there were multiple chunks (#28437)
• Propagate is_scalar from the input to the output of .sort() and .sort_by() (#28438)
• Insert missing coercions from Unknown(_) in list/array arithmetic (#28411)
• Resolve CSV column names overwrite in DSL->IR conversion (#28383)
• Avoid IEJoin rewrite for Categorical comparisons (#28427)
• Do not rewrite sort().reverse() to sort(descending=True) when maintain_order=True (#28403)
• Propagate bigidx to polars-plan from polars (#28396)
• Ensure BinaryView offset+len does not exceed i32::MAX where possible (#28048)
• Invalid offset in strptime (#28388)
• Incorrect schema type for decimal <-> primitive division (#28373)
• Panic in in-memory CSEE handling (#28371)
• Apply same type coercion to IsBetween as binary comparisons (#28300)
• Fix offset in arrow ffi export of sliced struct arrays (#28369)
• Fix cross filter not applied with sink and CSE (#28297)
• Fix panic on projection pushdown with caches (#28280)
• Fix write_json() null values in Array columns being written incorrectly as null (#28330)
• Fix EntityTooSmall on sink_ipc to S3 (#28255)
• Raise error instead of silent wrapping for select(len()) (#28355)
• Float16 groupby aggregates (#28361)
• Respect lexical ordering of Categorical in top_k/bottom_k (#28359)
• Support dtype-list schema overrides in scan_csv (#28226)
• Resolve unknown type in fused multiply add (#28321)
• Honor aws_checksum_algorithm when provided (#28328)
• Fix regression in sourcing HF_TOKEN (#28317)
• Raise on addition/subtraction between temporal and non-temporal Series (#28266)
• Rewrite with_columns on empty df to select during DSL -> IR (#28298)
• Fix sink deadlock regression (#28296)
• Avoid panic when consumer of vertical concat is done (#28272)
• Ensure predicate simplification is deterministically ordered (#28269)
• Don't attribute untimed execution to optimization in profile (#28273)
• Harden IPC mmap API (#28258)
• Classify S3 region request failures as IO errors (#28225)
• Incorrect inner dtype in ArrayChunked::from_aligned_values (#28249)
• Unsoundness in arg_sort_ascending (#28245)
• Add column length check to row encoding (#28248)
• Raise on implode of Object dtype instead of creating invalid List(Object) (#28246)
• Don't panic in qcut on degenerate float input (all-NaN, infinite, include_breaks) (#28220)
• Fix streaming Strptime feature flags (#28242)
• Return null not 0 for the first unbiased ewm_var/ewm_std value (#28235)
• Use after free in file cache (#28236)
• Incorrect length calculation in parallel hashmap (#28227)
• Avoid slice pushdown panic on shared cache inputs (#28157)
• Incorrect dtype for Unknown right literal in arithmetic (#28184)
• Remove unnecessary unsafe Python object downcast (#28189)
• Use-after-free in numpy ufunc FFI (#28195)
• Use-after-free in plugin registry (#28194)
• Unpickling for pl.when().then() (#28165)
• Reduce unknown casts (#28145)
• Consider a rolling_rank position invalid if ost.len() < min_samples (#28142)
• Incorrect broadcast with empty len in pl.concat_list (#28134)
• Incorrect sorted fast-path returning nan for grouped max (#28129)
• Fix panic on scan_parquet filter of fixed-size binary column (#28122)
• Fix decimal dynamic float cast (#28126)
• Fix pyiceberg key dot HDFS prefix filter (#28109)
• Fix projection pushdown panic on select(len()) after groupby (#28108)
• Close ResourceWarning leaks in database tests (#28066)
• Bad array len in UnionArray (#28079)
• Avoid panic on temporal extraction for datetime columns with nulls (#28054)
• Prevent panic in replace when old/new contain Expr or object dtype values (#27433)
• Fix qcut panic and incorrect bins on NaN input (#28020)
• Remove TrustedLen from Scan (#28055)
• Add a deprecation warning for .explode() without empty_as_null argument (#28040)
• Fix select(len()) incorrectly returned 0 when using scan_iceberg with pyiceberg as reader override (#28044)
• Ensure slice expr always observes input order (#28041)
• Fix projection pushdown with row index out of order (#28043)
• Fix cross-join predicates not applied when using sink_* functions (#28042)
• Grammar corrections (recommend to → recommend, allows to → allows using) (#28038)
• Ensure optimisations aren't omitted by cached IR nodes (#28004)
• Computed GROUP keys in SQL projections (#27989)
• Handle empty DataFrames in dt.truncate and dt.round (#26120)
• Address join alias state leakage in SQL CTEs (#27985)
• Support scanning file:// URIs with percent-encoded paths (#27876)
• Lower SQL [NOT] IN (subquery) to semi/anti join (#27888)
• Check for continuity across morsels in AsOf join node (#27461)
• Add test for projection pushdown with hconcat regression (#27937)
• Traverse caches only once in explain (#27939)
• Preserve null placement when collapsing sort.reverse() into single sort (#27918)
• Incorrect schema order for hstack in projection pushdown optimizer (#27920)
• Fix duplicated map_elements warning on streaming engine (

Note truncated.