2020 Changelog

- Fixed `Cannot rename ... errno: 22, strerror: Invalid argument` error on DDL query execution in Atomic database when running clickhouse-server in Docker on Mac OS. [#15024](https://github.com/ClickHouse/ClickHouse/pull/15024) ([tavplubix](https://github.com/tavplubix)).
- Fix crash in RIGHT or FULL JOIN with join\_algorith='auto' when memory limit exceeded and we should change HashJoin with MergeJoin. [#15002](https://github.com/ClickHouse/ClickHouse/pull/15002) ([Artem Zuikov](https://github.com/4ertus2)).
- Now settings `number_of_free_entries_in_pool_to_execute_mutation` and `number_of_free_entries_in_pool_to_lower_max_size_of_merge` can be equal to `background_pool_size`. [#14975](https://github.com/ClickHouse/ClickHouse/pull/14975) ([alesapin](https://github.com/alesapin)).
- Fix to make predicate push down work when subquery contains `finalizeAggregation` function. Fixes [#14847](https://github.com/ClickHouse/ClickHouse/issues/14847). [#14937](https://github.com/ClickHouse/ClickHouse/pull/14937) ([filimonov](https://github.com/filimonov)).
- Publish CPU frequencies per logical core in `system.asynchronous_metrics`. This fixes [#14923](https://github.com/ClickHouse/ClickHouse/issues/14923). [#14924](https://github.com/ClickHouse/ClickHouse/pull/14924) ([Alexander Kuzmenkov](https://github.com/akuzm)).
- `MaterializeMySQL` (experimental feature): Fixed `.metadata.tmp File exists` error. [#14898](https://github.com/ClickHouse/ClickHouse/pull/14898) ([Winter Zhang](https://github.com/zhang2014)).
- 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)).
- Fix SIGSEGV for an attempt to INSERT into StorageFile with file descriptor. [#14887](https://github.com/ClickHouse/ClickHouse/pull/14887) ([Azat Khuzhin](https://github.com/azat)).
- Fixed segfault in `cache` dictionary [#14837](https://github.com/ClickHouse/ClickHouse/issues/14837). [#14879](https://github.com/ClickHouse/ClickHouse/pull/14879) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- `MaterializeMySQL` (experimental feature): Fixed bug in parsing MySQL binlog events, which causes `Attempt to read after eof` and `Packet payload is not fully read` in `MaterializeMySQL` database engine. [#14852](https://github.com/ClickHouse/ClickHouse/pull/14852) ([Winter Zhang](https://github.com/zhang2014)).
- Fix rare error in `SELECT` queries when the queried column has `DEFAULT` expression which depends on the other column which also has `DEFAULT` and not present in select query and not exists on disk. Partially fixes [#14531](https://github.com/ClickHouse/ClickHouse/issues/14531). [#14845](https://github.com/ClickHouse/ClickHouse/pull/14845) ([alesapin](https://github.com/alesapin)).
- Fix a problem where the server may get stuck on startup while talking to ZooKeeper, if the configuration files have to be fetched from ZK (using the `from_zk` include option). This fixes [#14814](https://github.com/ClickHouse/ClickHouse/issues/14814). [#14843](https://github.com/ClickHouse/ClickHouse/pull/14843) ([Alexander Kuzmenkov](https://github.com/akuzm)).
- Fix wrong monotonicity detection for shrunk `Int -> Int` cast of signed types. It might lead to incorrect query result. This bug is unveiled in [#14513](https://github.com/ClickHouse/ClickHouse/issues/14513). [#14783](https://github.com/ClickHouse/ClickHouse/pull/14783) ([Amos Bird](https://github.com/amosbird)).
- `Replace` column transformer should replace identifiers with cloned ASTs. This fixes [#14695](https://github.com/ClickHouse/ClickHouse/issues/14695) . [#14734](https://github.com/ClickHouse/ClickHouse/pull/14734) ([Amos Bird](https://github.com/amosbird)).
- Fixed missed default database name in metadata of materialized view when executing `ALTER ... MODIFY QUERY`. [#14664](https://github.com/ClickHouse/ClickHouse/pull/14664) ([tavplubix](https://github.com/tavplubix)).
- 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)).
- 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)).
- Fix function `has` with `LowCardinality` of `Nullable`. [#14591](https://github.com/ClickHouse/ClickHouse/pull/14591) ([Mike](https://github.com/myrrc)).
- 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)).
- 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)).
- Fix a bug when converting `Nullable(String)` to Enum. Introduced by [#12745](https://github.com/ClickHouse/ClickHouse/pull/12745). This fixes [#14435](https://github.com/ClickHouse/ClickHouse/issues/14435). [#14530](https://github.com/ClickHouse/ClickHouse/pull/14530) ([Amos Bird](https://github.com/amosbird)).
- Fixed the incorrect sorting order of `Nullable` column. This fixes [#14344](https://github.com/ClickHouse/ClickHouse/issues/14344). [#14495](https://github.com/ClickHouse/ClickHouse/pull/14495) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- Fix `currentDatabase()` function cannot be used in `ON CLUSTER` ddl query. [#14211](https://github.com/ClickHouse/ClickHouse/pull/14211) ([Winter Zhang](https://github.com/zhang2014)).
- `MaterializeMySQL` (experimental feature): Fixed `Packet payload is not fully read` error in `MaterializeMySQL` database engine. [#14696](https://github.com/ClickHouse/ClickHouse/pull/14696) ([BohuTANG](https://github.com/BohuTANG)).