add join cardinality validation (#9278)
implement set operations for selector API (#9276)
keep sorted flag after Expr::truncate (#9275)
add "sql_expr" function (#9248)
rewrite correlation functions to expression architecture (#9258)
keep sorted flag on offset_by (#9253)
add expression json serde (#9236)
add intersection primitive for selector API (#9240)
building blocks for expression expansion sets (#9231)
Add ddof option to rolling_var and rolling_std (#8957)
immediately flatten nested unions (#9220)
Allow empty select/with_columns/groupby (#9205)
add a datetime selector (#9212)
support float expression on integers (#9210)
add dedicated selectors module, consolidating/expanding existing selector capabilities (#9204)
add binary to list<u8> cast (#9161)
groupby_dynamic by quarter. (#6842)
add arr.unique expression (#9159)
implement explode for DataType::Array (#9157)
Decimal type: sum, min, max aggregations in select and agg context. (#9135)
Decimal arithmetic (#9123)
support decimals as cast types in csv parser (#9121)
Improve error handling for repeat (#9117)

🐞 Bug fixes

fix pyarrow dataset literal filter (#9274)
raise on invalid sort_by (#9262)
match missing Array and Struct classes in FromPyObject (#9271)
correct ne/e_missing schema (#9257)
fix cached reproject offsets (#9254)
delay opening files in streaming engine (#9251)
ensure agg(F(lit)) == lit (#9222)
don't SO on concat(expressions) (#9214)
df.apply first rechunk (#9211)
clip window_size to length in rolling_apply (#9209)
raise error on invalid df.apply return (#9207)
Handle edge cases of named select input (#9198)
rolling_apply window_size == len (#9181)
respect time zone in strptime/to_datetime when exact=False (#9171)
make null chunking behavior equal to other dtypes (#9176)
return single numpy array in Array dtype -> numpy (#9164)
fix regression in boolean nulls comparison (#9142)
fix struct null_count if fields are null arrays (#9151)
Fix DataFrame.to_arrow() for 0x0 dataframes (#9144)
categorical construction from null values (#9145)
let apply caller determine if length needs to be checked. (#9140)
struct is_in should upcast numeric types (#9110)
Restore functionality of name arg for date_range (#9107)
bubble up dtype when converting from arrow (#9120)

🛠️ Other improvements

Fix grammar and add periods in Expr.over docs (#9244)
Update linting for py-polars crate (#9242)
Deprecate exprs=... input for select/with_columns/agg/struct (#9219)
Enable parallelization in Python Windows tests (#9232)
Use pytest tmp_path (#9206)
Build docs in parallel (#9229)
Unify Python docs workflows (#9228)
add docstring to __array__ methods (#8055)
Update expr parsing util to return PyExpr (#9166)
update pyo3 requirement from 0.18 to 0.19 (#9155)
clarify how the windows are formed in the rolling_* functions (#9192)
stabilise polars importtime check (#9196)
fix "to_decimal" docstring (#9197)
note that exact=False is a performance footgun (#9186)
change decimal inference and argument order (#9133)
Cache Rust build on main branch (#9130)
Improve df.clear() docs (#8809)
Bump maturin to 1.0.1 (#9115)
Bump lint dependency versions (#9116)

Thank you to all our contributors for making this release possible! @DeflateAwning, @MarcoGorelli, @alexander-beedie, @ankane, @avimallu, @bfeif, @dependabot, @dependabot[bot], @jonashaag, @josh, @lorentzenchr, @magarick, @ritchie46, @stinodego, @universalmind303 and @zundertj