rust polars 0.20.0

[ritchie46]

New rust polars release! 🚀

This release of 286 commits is here thanks to the contributions of: (in no specific order):

• @moritzwilksch
• @JakobGM
• @illumination-k
• @tamasfe
• @ghuls
• @alexander-beedie
• @Maxyme
• @universalmind303
• @qiemem
• @glennpierce
• @nmandery
• @ilsley
• @marcvanheerden

did I forget your contribution, please ping me, I do this manually 🙈

• Full changelog
• crates.io
• documentation

Most notable changes are:

• Many bug fixes.
• Many performance improvements.

features

• Made representation of groups tuples more cache friendly Groups slice #2431

• Remove Seek requirement of readers

• Add groupby_rolling as new entrance to expression API.

• Improve CSV parsers stability and performance on several occasions

• Horizontal aggregations are parallelized parallelize horizontal aggregations #2454

• Reduce pivot code bloat and improve performance improve pivot performance #2458

• Struct data type added.

• Extend methods that allow modification of the same memory if Arc::ref_count == 1

• Avro readers and writers.

• Improved rules of window expressions.

• Support for us time unit.

• Parquet use statistics in query optimizations.

• Optimize projections in lazy computations. (Mostly useful when you deal with a large number of columns e.g. millions).

• Improve performance and flexibility of melt operation @2799

• new expressions

  • str.split
  • str.split_inclusive
  • arr.join
  • unique_stable
  • str.split_exact
  • count expression that does not require column names
  • arr.arg_min
  • arr.arg_max
  • arr.diff
  • arr.shift

Update to arrow2 0.10.0

See the 0.10.0 release for all upstream improvements.