* Unified code which placed data from columns into HashTable (ColumnsHashing.h). Refactored `Aggregator`, `Join`, `Set`, `arrayUniq`, `arrayEnumerateUniq` and `arrayEnumerateDense`. [#4128](https://github.com/yandex/ClickHouse/pull/4128)([KochetovNicolai](https://github.com/KochetovNicolai))
* A lot of Interpreters refactoring. [#4193](https://github.com/yandex/ClickHouse/pull/4193)[#4154](https://github.com/yandex/ClickHouse/pull/4154) [#4307](https://github.com/yandex/ClickHouse/pull/4307)([#43])([Artem Zuikov](https://github.com/4ertus2))
