2020 Changelog

- Fix UBSan report in Decimal parse. This fixes [#7540](https://github.com/ClickHouse/ClickHouse/issues/7540). [#10512](https://github.com/ClickHouse/ClickHouse/pull/10512) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix potential floating point exception when parsing DateTime64. This fixes [#11374](https://github.com/ClickHouse/ClickHouse/issues/11374). [#11875](https://github.com/ClickHouse/ClickHouse/pull/11875) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix rare crash caused by using `Nullable` column in prewhere condition. [#11895](https://github.com/ClickHouse/ClickHouse/pull/11895) [#11608](https://github.com/ClickHouse/ClickHouse/issues/11608) [#11869](https://github.com/ClickHouse/ClickHouse/pull/11869) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Don't allow arrayJoin inside higher order functions. It was leading to broken protocol synchronization. This closes [#3933](https://github.com/ClickHouse/ClickHouse/issues/3933). [#11846](https://github.com/ClickHouse/ClickHouse/pull/11846) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix wrong result of comparison of FixedString with constant String. This fixes [#11393](https://github.com/ClickHouse/ClickHouse/issues/11393). This bug appeared in version 20.4. [#11828](https://github.com/ClickHouse/ClickHouse/pull/11828) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix wrong result for `if` with NULLs in condition. [#11807](https://github.com/ClickHouse/ClickHouse/pull/11807) ([Artem Zuikov](https://github.com/4ertus2)).
- Fix using too many threads for queries. [#11788](https://github.com/ClickHouse/ClickHouse/pull/11788) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed `Scalar does not exist` exception when using `WITH <scalar subquery> ...` in `SELECT ... FROM merge_tree_table ...` [#11621](https://github.com/ClickHouse/ClickHouse/issues/11621). [#11767](https://github.com/ClickHouse/ClickHouse/pull/11767) ([Amos Bird](https://github.com/amosbird)).
- Fix unexpected behaviour of queries like `SELECT *, xyz.*` which were success while an error expected. [#11753](https://github.com/ClickHouse/ClickHouse/pull/11753) ([hexiaoting](https://github.com/hexiaoting)).
- Now replicated fetches will be cancelled during metadata alter. [#11744](https://github.com/ClickHouse/ClickHouse/pull/11744) ([alesapin](https://github.com/alesapin)).
- Parse metadata stored in zookeeper before checking for equality. [#11739](https://github.com/ClickHouse/ClickHouse/pull/11739) ([Azat Khuzhin](https://github.com/azat)).
- Fixed LOGICAL\_ERROR caused by wrong type deduction of complex literals in Values input format. [#11732](https://github.com/ClickHouse/ClickHouse/pull/11732) ([tavplubix](https://github.com/tavplubix)).
- Fix `ORDER BY ... WITH FILL` over const columns. [#11697](https://github.com/ClickHouse/ClickHouse/pull/11697) ([Anton Popov](https://github.com/CurtizJ)).
- Fix very rare race condition in SYSTEM SYNC REPLICA. If the replicated table is created and at the same time from the separate connection another client is issuing `SYSTEM SYNC REPLICA` command on that table (this is unlikely, because another client should be aware that the table is created), it's possible to get nullptr dereference. [#11691](https://github.com/ClickHouse/ClickHouse/pull/11691) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Pass proper timeouts when communicating with XDBC bridge. Recently timeouts were not respected when checking bridge liveness and receiving meta info. [#11690](https://github.com/ClickHouse/ClickHouse/pull/11690) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix `LIMIT n WITH TIES` usage together with `ORDER BY` statement, which contains aliases. [#11689](https://github.com/ClickHouse/ClickHouse/pull/11689) ([Anton Popov](https://github.com/CurtizJ)).
- Fix possible `Pipeline stuck` for selects with parallel `FINAL`. Fixes [#11636](https://github.com/ClickHouse/ClickHouse/issues/11636). [#11682](https://github.com/ClickHouse/ClickHouse/pull/11682) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fix error which leads to an incorrect state of `system.mutations`. It may show that whole mutation is already done but the server still has `MUTATE_PART` tasks in the replication queue and tries to execute them. This fixes [#11611](https://github.com/ClickHouse/ClickHouse/issues/11611). [#11681](https://github.com/ClickHouse/ClickHouse/pull/11681) ([alesapin](https://github.com/alesapin)).
- Fix syntax hilite in CREATE USER query. [#11664](https://github.com/ClickHouse/ClickHouse/pull/11664) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Add support for regular expressions with case-insensitive flags. This fixes [#11101](https://github.com/ClickHouse/ClickHouse/issues/11101) and fixes [#11506](https://github.com/ClickHouse/ClickHouse/issues/11506). [#11649](https://github.com/ClickHouse/ClickHouse/pull/11649) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Remove trivial count query optimization if row-level security is set. In previous versions the user get total count of records in a table instead filtered. This fixes [#11352](https://github.com/ClickHouse/ClickHouse/issues/11352). [#11644](https://github.com/ClickHouse/ClickHouse/pull/11644) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix bloom filters for String (data skipping indices). [#11638](https://github.com/ClickHouse/ClickHouse/pull/11638) ([Azat Khuzhin](https://github.com/azat)).
- Without `-q` option the database does not get created at startup. [#11604](https://github.com/ClickHouse/ClickHouse/pull/11604) ([giordyb](https://github.com/giordyb)).
- Fix error `Block structure mismatch` for queries with sampling reading from `Buffer` table. [#11602](https://github.com/ClickHouse/ClickHouse/pull/11602) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fix wrong exit code of the clickhouse-client, when `exception.code() % 256 == 0`. [#11601](https://github.com/ClickHouse/ClickHouse/pull/11601) ([filimonov](https://github.com/filimonov)).
- Fix race conditions in CREATE/DROP of different replicas of ReplicatedMergeTree. Continue to work if the table was not removed completely from ZooKeeper or not created successfully. This fixes [#11432](https://github.com/ClickHouse/ClickHouse/issues/11432). [#11592](https://github.com/ClickHouse/ClickHouse/pull/11592) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix trivial error in log message about "Mark cache size was lowered" at server startup. This closes [#11399](https://github.com/ClickHouse/ClickHouse/issues/11399). [#11589](https://github.com/ClickHouse/ClickHouse/pull/11589) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix error `Size of offsets does not match size of column` for queries with `PREWHERE column in (subquery)` and `ARRAY JOIN`. [#11580](https://github.com/ClickHouse/ClickHouse/pull/11580) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed rare segfault in `SHOW CREATE TABLE` Fixes [#11490](https://github.com/ClickHouse/ClickHouse/issues/11490). [#11579](https://github.com/ClickHouse/ClickHouse/pull/11579) ([tavplubix](https://github.com/tavplubix)).
- All queries in HTTP session have had the same query\_id. It is fixed. [#11578](https://github.com/ClickHouse/ClickHouse/pull/11578) ([tavplubix](https://github.com/tavplubix)).
- Now clickhouse-server docker container will prefer IPv6 checking server aliveness. [#11550](https://github.com/ClickHouse/ClickHouse/pull/11550) ([Ivan Starkov](https://github.com/istarkov)).
- Fix the error `Data compressed with different methods` that can happen if `min_bytes_to_use_direct_io` is enabled and PREWHERE is active and using SAMPLE or high number of threads. This fixes [#11539](https://github.com/ClickHouse/ClickHouse/issues/11539). [#11540](https://github.com/ClickHouse/ClickHouse/pull/11540) ([alexey-milovidov](https://github.com/alexey-milovidov)).