Move to prewhere improvement

Avoid performance degradation in few degenerate cases: added fast path for tautological compares #4405

Fixed error with underestimation of data size to read when choosing O_DIRECT mode

Improve push-down logic for joined statements

Implemented function "flatten"

Merge branch 'array-flatten-function' of https://github.com/kzon/ClickHouse into kzon-array-flatten-function

Fixed fuzz test in UBSan

Set update_time on full executable dictionary update

Fix crash on JOIN with array or tuple

DOCAPI-5436: Update of the FixedString data type description.

A Proper lookup table that uses HashTable's API