### ClickHouse release v21.2.3.15-stable FIXME as compared to v21.2.2.8-stable
#### Bug Fix
* Backported in [#20241](https://github.com/ClickHouse/ClickHouse/issues/20241): Fix a bug that moving pieces to destination table may failed in case of launching multiple clickhouse-copiers. [#19743](https://github.com/ClickHouse/ClickHouse/pull/19743) ([madianjun](https://github.com/mdianjun)).
* Backported in [#20296](https://github.com/ClickHouse/ClickHouse/issues/20296): * Bugfix in StorageJoin. [#20079](https://github.com/ClickHouse/ClickHouse/pull/20079) ([Vladimir C](https://github.com/vdimir)).
* Backported in [#20389](https://github.com/ClickHouse/ClickHouse/issues/20389): The `MongoDB` table engine now establishes connection only when it's going to read data. `ATTACH TABLE` won't try to connect anymore. [#20110](https://github.com/ClickHouse/ClickHouse/pull/20110) ([Vitaly Baranov](https://github.com/vitlibar)).
* Backported in [#20270](https://github.com/ClickHouse/ClickHouse/issues/20270): Fix CTE when using in INSERT SELECT. This fixes [#20187](https://github.com/ClickHouse/ClickHouse/issues/20187), fixes [#20195](https://github.com/ClickHouse/ClickHouse/issues/20195). [#20211](https://github.com/ClickHouse/ClickHouse/pull/20211) ([Amos Bird](https://github.com/amosbird)).
* Backported in [#20329](https://github.com/ClickHouse/ClickHouse/issues/20329): Fix rare server crash on config reload during the shutdown. Fixes [#19689](https://github.com/ClickHouse/ClickHouse/issues/19689). [#20224](https://github.com/ClickHouse/ClickHouse/pull/20224) ([alesapin](https://github.com/alesapin)).
* Backported in [#20324](https://github.com/ClickHouse/ClickHouse/issues/20324): Fix exception during vertical merge for `MergeTree` table engines family which don't allow to perform vertical merges. Fixes [#20259](https://github.com/ClickHouse/ClickHouse/issues/20259). [#20279](https://github.com/ClickHouse/ClickHouse/pull/20279) ([alesapin](https://github.com/alesapin)).
* Backported in [#20333](https://github.com/ClickHouse/ClickHouse/issues/20333): Restrict to `DROP` or `RENAME` version column of `*CollapsingMergeTree` and `ReplacingMergeTree` table engines. [#20300](https://github.com/ClickHouse/ClickHouse/pull/20300) ([alesapin](https://github.com/alesapin)).
* Backported in [#20365](https://github.com/ClickHouse/ClickHouse/issues/20365): Fix too often retries of failed background tasks for `ReplicatedMergeTree` table engines family. This could lead to too verbose logging and increased CPU load. Fixes [#20203](https://github.com/ClickHouse/ClickHouse/issues/20203). [#20335](https://github.com/ClickHouse/ClickHouse/pull/20335) ([alesapin](https://github.com/alesapin)).
* Backported in [#20379](https://github.com/ClickHouse/ClickHouse/issues/20379): Fix incorrect result of binary operations between two constant decimals of different scale. Fixes [#20283](https://github.com/ClickHouse/ClickHouse/issues/20283). [#20339](https://github.com/ClickHouse/ClickHouse/pull/20339) ([Maksim Kita](https://github.com/kitaisreal)).
* Backported in [#20376](https://github.com/ClickHouse/ClickHouse/issues/20376): Fix null dereference with `join_use_nulls=1`. [#20344](https://github.com/ClickHouse/ClickHouse/pull/20344) ([Azat Khuzhin](https://github.com/azat)).
* Backported in [#20361](https://github.com/ClickHouse/ClickHouse/issues/20361): Avoid invalid dereference in RANGE_HASHED() dictionary. [#20345](https://github.com/ClickHouse/ClickHouse/pull/20345) ([Azat Khuzhin](https://github.com/azat)).
#### NO CL ENTRY
* NO CL ENTRY: 'Revert "Backport [#20224](https://github.com/ClickHouse/ClickHouse/issues/20224) to 21.2: Fix access control manager destruction order"'. [#20397](https://github.com/ClickHouse/ClickHouse/pull/20397) ([alesapin](https://github.com/alesapin)).
* Handle syntax error for ARRAY JOIN with no args [#20223](https://github.com/ClickHouse/ClickHouse/pull/20223) ([Vladimir C](https://github.com/vdimir)).
