Changelog Polars (Rust crate)

The Python bindings polars have their own changelog.

[future] Polars v0.13

performance
- Vast reduction of compile times by making compilation dtypes of Series opt-in.
- Fast multi-threaded csv parser. Fixes multiple gripes of old parser.
features
- Series / ChunkedArray implementations
  - Series::week
  - Series::weekday
  - Series::arg_min
  - Series::arg_max
breaking
- ChunkedArray::arg_unique return UInt32Chunked instead of Vec
bug fixes
- various

CSV Read IO
- Parallel csv reader
Sample DataFrames/ Series
Performance increase in take kernel
Performance increase in ChunkedArray builders
Join operation on multiple columns.
~3.5 x performance increase in groupby operations (measured on db-benchmark), due to embarrassingly parallel grouping and better branch prediction (tight loops).
Performance increase on join operation due to better branch prediction.
Categorical datatype and global string cache (BETA).
Lazy
- Lot's of bug fixes in optimizer.
- Parallel execution of Physical plan
- Partition window function
- More simplify expression optimizations.
- Caching
- Alpha release of Aggregate pushdown optimization.
Start of general Object type in ChunkedArray/DataFrames/Series