### ClickHouse release v20.9.4.76-stable FIXME as compared to v20.9.3.45-stable

#### Improvement
* Backported in [#16145](https://github.com/ClickHouse/ClickHouse/issues/16145): Now it's allowed to execute `ALTER ... ON CLUSTER` queries regardless of the `<internal_replication>` setting in cluster config. [#16075](https://github.com/ClickHouse/ClickHouse/pull/16075) ([alesapin](https://github.com/alesapin)).
* Backported in [#16312](https://github.com/ClickHouse/ClickHouse/issues/16312): Add allow_nondeterministic_optimize_skip_unused_shards (to allow non deterministic like rand() or dictGet() in sharding key). [#16105](https://github.com/ClickHouse/ClickHouse/pull/16105) ([Azat Khuzhin](https://github.com/azat)).

#### Bug Fix
* Backported in [#15618](https://github.com/ClickHouse/ClickHouse/issues/15618): Throw an error when a single parameter is passed to ReplicatedMergeTree instead of ignoring it. [#15516](https://github.com/ClickHouse/ClickHouse/pull/15516) ([nvartolomei](https://github.com/nvartolomei)).
* Backported in [#16201](https://github.com/ClickHouse/ClickHouse/issues/16201): Decrement the `ReadonlyReplica` metric when detaching read-only tables. This fixes [#15598](https://github.com/ClickHouse/ClickHouse/issues/15598). [#15592](https://github.com/ClickHouse/ClickHouse/pull/15592) ([sundyli](https://github.com/sundy-li)).
* Backported in [#16229](https://github.com/ClickHouse/ClickHouse/issues/16229): Fixed bug with globs in S3 table function, region from URL was not applied to S3 client configuration. [#15646](https://github.com/ClickHouse/ClickHouse/pull/15646) ([Vladimir Chebotarev](https://github.com/excitoon)).
* Backported in [#15870](https://github.com/ClickHouse/ClickHouse/issues/15870): Fix error `Cannot add simple transform to empty Pipe` which happened while reading from `Buffer` table which has different structure than destination table. It was possible if destination table returned empty result for query. Fixes [#15529](https://github.com/ClickHouse/ClickHouse/issues/15529). [#15662](https://github.com/ClickHouse/ClickHouse/pull/15662) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
* Backported in [#15774](https://github.com/ClickHouse/ClickHouse/issues/15774): Fixed too low default value of `max_replicated_logs_to_keep` setting, which might cause replicas to become lost too often. Improve lost replica recovery process by choosing the most up-to-date replica to clone. Also do not remove old parts from lost replica, detach them instead. [#15701](https://github.com/ClickHouse/ClickHouse/pull/15701) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#15798](https://github.com/ClickHouse/ClickHouse/issues/15798): Fix some cases of queries, in which only virtual columns are selected. Previously `Not found column _nothing in block` exception may be thrown. Fixes [#12298](https://github.com/ClickHouse/ClickHouse/issues/12298). [#15756](https://github.com/ClickHouse/ClickHouse/pull/15756) ([Anton Popov](https://github.com/CurtizJ)).
* Backported in [#15868](https://github.com/ClickHouse/ClickHouse/issues/15868): Fix `select count()` inaccuracy for MaterializeMySQL. [#15767](https://github.com/ClickHouse/ClickHouse/pull/15767) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#15901](https://github.com/ClickHouse/ClickHouse/issues/15901): Fix exception `Block structure mismatch` in `SELECT ... ORDER BY DESC` queries which were executed after `ALTER MODIFY COLUMN` query. Fixes [#15800](https://github.com/ClickHouse/ClickHouse/issues/15800). [#15852](https://github.com/ClickHouse/ClickHouse/pull/15852) ([alesapin](https://github.com/alesapin)).
* Backported in [#15924](https://github.com/ClickHouse/ClickHouse/issues/15924): Now exception will be thrown when `ALTER MODIFY COLUMN ... DEFAULT ...` has incompatible default with column type. Fixes [#15854](https://github.com/ClickHouse/ClickHouse/issues/15854). [#15858](https://github.com/ClickHouse/ClickHouse/pull/15858) ([alesapin](https://github.com/alesapin)).
* Backported in [#15919](https://github.com/ClickHouse/ClickHouse/issues/15919): Fix possible deadlocks in RBAC. [#15875](https://github.com/ClickHouse/ClickHouse/pull/15875) ([Vitaly Baranov](https://github.com/vitlibar)).
* Backported in [#16167](https://github.com/ClickHouse/ClickHouse/issues/16167): Fix incorrect empty result for query from `Distributed` table if query has `WHERE`, `PREWHERE` and `GLOBAL IN`. Fixes [#15792](https://github.com/ClickHouse/ClickHouse/issues/15792). [#15933](https://github.com/ClickHouse/ClickHouse/pull/15933) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
* Backported in [#16356](https://github.com/ClickHouse/ClickHouse/issues/16356): Fixed `DROP TABLE IF EXISTS` failure with `Table ... doesn't exist` error when table is concurrently renamed (for Atomic database engine). Fixed rare deadlock when concurrently executing some DDL queries with multiple tables (like `DROP DATABASE` and `RENAME TABLE`) Fixed `DROP/DETACH DATABASE` failure with `Table ... doesn't exist` when concurrently executing `DROP/DETACH TABLE`. [#15934](https://github.com/ClickHouse/ClickHouse/pull/15934) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#15971](https://github.com/ClickHouse/ClickHouse/issues/15971): Fix a crash when database creation fails. [#15954](https://github.com/ClickHouse/ClickHouse/pull/15954) ([Winter Zhang](https://github.com/zhang2014)).
* Backported in [#16022](https://github.com/ClickHouse/ClickHouse/issues/16022): Fix ambiguity in parsing of settings profiles: `CREATE USER ... SETTINGS profile readonly` is now considered as using a profile named `readonly`, not a setting named `profile` with the readonly constraint. This fixes [#15628](https://github.com/ClickHouse/ClickHouse/issues/15628). [#15982](https://github.com/ClickHouse/ClickHouse/pull/15982) ([Vitaly Baranov](https://github.com/vitlibar)).
* Backported in [#16218](https://github.com/ClickHouse/ClickHouse/issues/16218): Fix rare segfaults when inserting into or selecting from MaterializedView and concurrently dropping target table (for Atomic database engine). [#15984](https://github.com/ClickHouse/ClickHouse/pull/15984) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#16026](https://github.com/ClickHouse/ClickHouse/issues/16026): Prevent replica hang for 5-10 mins when replication error happens after a period of inactivity. [#15987](https://github.com/ClickHouse/ClickHouse/pull/15987) ([filimonov](https://github.com/filimonov)).
* Backported in [#16091](https://github.com/ClickHouse/ClickHouse/issues/16091): Allow to use direct layout for dictionaries with complex keys. [#16007](https://github.com/ClickHouse/ClickHouse/pull/16007) ([Anton Popov](https://github.com/CurtizJ)).
* Backported in [#16361](https://github.com/ClickHouse/ClickHouse/issues/16361): Fix collate name & charset name parser and support `length = 0` for string type. [#16008](https://github.com/ClickHouse/ClickHouse/pull/16008) ([Winter Zhang](https://github.com/zhang2014)).
* Backported in [#16140](https://github.com/ClickHouse/ClickHouse/issues/16140): Fix `ALTER MODIFY ... ORDER BY` query hang for `ReplicatedVersionedCollapsingMergeTree`. This fixes [#15980](https://github.com/ClickHouse/ClickHouse/issues/15980). [#16011](https://github.com/ClickHouse/ClickHouse/pull/16011) ([alesapin](https://github.com/alesapin)).
* Backported in [#16079](https://github.com/ClickHouse/ClickHouse/issues/16079): Fixes [#15780](https://github.com/ClickHouse/ClickHouse/issues/15780) regression, e.g. indexOf([1, 2, 3], toLowCardinality(1)) now is prohibited but it should not be. [#16038](https://github.com/ClickHouse/ClickHouse/pull/16038) ([Mike Kot](https://github.com/myrrc)).
* Backported in [#16298](https://github.com/ClickHouse/ClickHouse/issues/16298): Fix dictGet in sharding_key (and similar places, i.e. when the function context is stored permanently). [#16205](https://github.com/ClickHouse/ClickHouse/pull/16205) ([Azat Khuzhin](https://github.com/azat)).
* Backported in [#16232](https://github.com/ClickHouse/ClickHouse/issues/16232): Fix the case when memory can be overallocated regardless to the limit. This closes [#14560](https://github.com/ClickHouse/ClickHouse/issues/14560). [#16206](https://github.com/ClickHouse/ClickHouse/pull/16206) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
* Backported in [#16326](https://github.com/ClickHouse/ClickHouse/issues/16326): Fix a possible memory leak during `GROUP BY` with string keys, caused by an error in `TwoLevelStringHashTable` implementation. [#16264](https://github.com/ClickHouse/ClickHouse/pull/16264) ([Amos Bird](https://github.com/amosbird)).
* Backported in [#16377](https://github.com/ClickHouse/ClickHouse/issues/16377): Fix async Distributed INSERT w/ prefer_localhost_replica=0 and internal_replication. [#16358](https://github.com/ClickHouse/ClickHouse/pull/16358) ([Azat Khuzhin](https://github.com/azat)).
* Backported in [#16432](https://github.com/ClickHouse/ClickHouse/issues/16432): Fix group by with totals/rollup/cube modifers and min/max functions over group by keys. Fixes [#16393](https://github.com/ClickHouse/ClickHouse/issues/16393). [#16397](https://github.com/ClickHouse/ClickHouse/pull/16397) ([Anton Popov](https://github.com/CurtizJ)).
* Backported in [#16449](https://github.com/ClickHouse/ClickHouse/issues/16449): Fix double free in case of exception in function `dictGet`. It could have happened if dictionary was loaded with error. [#16429](https://github.com/ClickHouse/ClickHouse/pull/16429) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).

#### Other
* Unfold `{database}`, `{table}` and `{uuid}` macros in `ReplicatedMergeTree` arguments on table creation. [#16160](https://github.com/ClickHouse/ClickHouse/pull/16160) ([Alexander Tokmakov](https://github.com/tavplubix)).