### ClickHouse release v20.8.3.18-stable FIXME as compared to v20.8.2.3-stable

#### Improvement
* Backported in [#14874](https://github.com/ClickHouse/ClickHouse/issues/14874): Allow using multi-volume storage configuration in storage Distributed. [#14839](https://github.com/ClickHouse/ClickHouse/pull/14839) ([Pavel Kovalenko](https://github.com/Jokser)).
* Speed up server shutdown process if there are ongoing S3 requests. [#14858](https://github.com/ClickHouse/ClickHouse/pull/14858) ([Pavel Kovalenko](https://github.com/Jokser)).

#### Bug Fix
* Backported in [#14600](https://github.com/ClickHouse/ClickHouse/issues/14600): Fix rare segfaults in functions with combinator -Resample, which could appear in result of overflow with very large parameters. [#14562](https://github.com/ClickHouse/ClickHouse/pull/14562) ([Anton Popov](https://github.com/CurtizJ)).
* Backported in [#14727](https://github.com/ClickHouse/ClickHouse/issues/14727): Cleanup data directory after Zookeeper exceptions during CreateQuery for StorageReplicatedMergeTree Engine. [#14563](https://github.com/ClickHouse/ClickHouse/pull/14563) ([Bharat Nallan](https://github.com/bharatnc)).
* Backported in [#14653](https://github.com/ClickHouse/ClickHouse/issues/14653): Added the checker as neither calling `lc->isNullable()` nor calling `ls->getDictionaryPtr()->isNullable()` would return the correct result. [#14591](https://github.com/ClickHouse/ClickHouse/pull/14591) ([Mike Kot](https://github.com/myrrc)).
* Backported in [#14666](https://github.com/ClickHouse/ClickHouse/issues/14666): Fix wrong Decimal multiplication result caused wrong decimal scale of result column. [#14603](https://github.com/ClickHouse/ClickHouse/pull/14603) ([Artem Zuikov](https://github.com/4ertus2)).
* Backported in [#14793](https://github.com/ClickHouse/ClickHouse/issues/14793): Fix bug when `ALTER UPDATE` mutation with Nullable column in assignment expression and constant value (like `UPDATE x = 42`) leads to incorrect value in column or segfault. Fixes [#13634](https://github.com/ClickHouse/ClickHouse/issues/13634), [#14045](https://github.com/ClickHouse/ClickHouse/issues/14045). [#14646](https://github.com/ClickHouse/ClickHouse/pull/14646) ([alesapin](https://github.com/alesapin)).
* Backported in [#14722](https://github.com/ClickHouse/ClickHouse/issues/14722): Fixed missed default database name in metadata of materialized view when executing `ALTER ... MODIFY QUERY`. [#14664](https://github.com/ClickHouse/ClickHouse/pull/14664) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#14910](https://github.com/ClickHouse/ClickHouse/issues/14910): Fix SIGSEGV for an attempt to INSERT into StorageFile(fd). [#14887](https://github.com/ClickHouse/ClickHouse/pull/14887) ([Azat Khuzhin](https://github.com/azat)).
* Backported in [#14943](https://github.com/ClickHouse/ClickHouse/issues/14943): Fix the issue when some invocations of `extractAllGroups` function may trigger "Memory limit exceeded" error. This fixes [#13383](https://github.com/ClickHouse/ClickHouse/issues/13383). [#14889](https://github.com/ClickHouse/ClickHouse/pull/14889) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
