* Now server reuse threads from global thread pool. This affects performance in some corner cases. [#4150](https://github.com/yandex/ClickHouse/pull/4150)([alexey-milovidov](https://github.com/alexey-milovidov))
### Improvements
* Implemented AIO support for FreeBSD. [#4305](https://github.com/yandex/ClickHouse/pull/4305)([Vitaly Baranov](https://github.com/vitlibar))
* Implemented AIO support for FreeBSD. [#4305](https://github.com/yandex/ClickHouse/pull/4305)([urgordeadbeef](https://github.com/urgordeadbeef))
*`SELECT * FROM a JOIN b USING a, b` now return `a` and `b` columns only from the left table. [#4141](https://github.com/yandex/ClickHouse/pull/4141)([Artem Zuikov](https://github.com/4ertus2))
* Improved hints selector now it is similar to clang SimpleTypoCorrector. [#4337](https://github.com/yandex/ClickHouse/pull/4337)([Danila Kutenin](https://github.com/danlark1))
* Added hints while user make typo in function name or type in command line client. [#4239](https://github.com/yandex/ClickHouse/pull/4239)([Danila Kutenin](https://github.com/danlark1))
