2020 Changelog

- Fix the issue when server can stop accepting connections in very rare cases. [#17542](https://github.com/ClickHouse/ClickHouse/pull/17542) ([Amos Bird](https://github.com/amosbird)).
- Fixed `Function not implemented` error when executing `RENAME` query in `Atomic` database with ClickHouse running on Windows Subsystem for Linux. Fixes [#17661](https://github.com/ClickHouse/ClickHouse/issues/17661). [#17664](https://github.com/ClickHouse/ClickHouse/pull/17664) ([tavplubix](https://github.com/tavplubix)).
- Do not restore parts from WAL if `in_memory_parts_enable_wal` is disabled. [#17802](https://github.com/ClickHouse/ClickHouse/pull/17802) ([detailyang](https://github.com/detailyang)).
- fix incorrect initialization of `max_compress_block_size` of MergeTreeWriterSettings with `min_compress_block_size`. [#17833](https://github.com/ClickHouse/ClickHouse/pull/17833) ([flynn](https://github.com/ucasFL)).
- Exception message about max table size to drop was displayed incorrectly. [#17764](https://github.com/ClickHouse/ClickHouse/pull/17764) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fixed possible segfault when there is not enough space when inserting into `Distributed` table. [#17737](https://github.com/ClickHouse/ClickHouse/pull/17737) ([tavplubix](https://github.com/tavplubix)).
- Fixed problem when ClickHouse fails to resume connection to MySQL servers. [#17681](https://github.com/ClickHouse/ClickHouse/pull/17681) ([Alexander Kazakov](https://github.com/Akazz)).
- In might be determined incorrectly if cluster is circular- (cross-) replicated or not when executing `ON CLUSTER` query due to race condition when `pool_size` > 1. It's fixed. [#17640](https://github.com/ClickHouse/ClickHouse/pull/17640) ([tavplubix](https://github.com/tavplubix)).
- Exception `fmt::v7::format_error` can be logged in background for MergeTree tables. This fixes [#17613](https://github.com/ClickHouse/ClickHouse/issues/17613). [#17615](https://github.com/ClickHouse/ClickHouse/pull/17615) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- When clickhouse-client is used in interactive mode with multiline queries, single line comment was erronously extended till the end of query. This fixes [#13654](https://github.com/ClickHouse/ClickHouse/issues/13654). [#17565](https://github.com/ClickHouse/ClickHouse/pull/17565) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix alter query hang when the corresponding mutation was killed on the different replica. Fixes [#16953](https://github.com/ClickHouse/ClickHouse/issues/16953). [#17499](https://github.com/ClickHouse/ClickHouse/pull/17499) ([alesapin](https://github.com/alesapin)).
- Fix issue when mark cache size was underestimated by clickhouse. It may happen when there are a lot of tiny files with marks. [#17496](https://github.com/ClickHouse/ClickHouse/pull/17496) ([alesapin](https://github.com/alesapin)).
- Fix `ORDER BY` with enabled setting `optimize_redundant_functions_in_order_by`. [#17471](https://github.com/ClickHouse/ClickHouse/pull/17471) ([Anton Popov](https://github.com/CurtizJ)).
- Fix duplicates after `DISTINCT` which were possible because of incorrect optimization. Fixes [#17294](https://github.com/ClickHouse/ClickHouse/issues/17294). [#17296](https://github.com/ClickHouse/ClickHouse/pull/17296) ([li chengxiang](https://github.com/chengxianglibra)). [#17439](https://github.com/ClickHouse/ClickHouse/pull/17439) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fix crash while reading from `JOIN` table with `LowCardinality` types. Fixes [#17228](https://github.com/ClickHouse/ClickHouse/issues/17228). [#17397](https://github.com/ClickHouse/ClickHouse/pull/17397) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- fix `toInt256(inf)` stack overflow. Int256 is an experimental feature. Closed [#17235](https://github.com/ClickHouse/ClickHouse/issues/17235). [#17257](https://github.com/ClickHouse/ClickHouse/pull/17257) ([flynn](https://github.com/ucasFL)).
- Fix possible `Unexpected packet Data received from client` error logged for Distributed queries with `LIMIT`. [#17254](https://github.com/ClickHouse/ClickHouse/pull/17254) ([Azat Khuzhin](https://github.com/azat)).
- Fix set index invalidation when there are const columns in the subquery. This fixes [#17246](https://github.com/ClickHouse/ClickHouse/issues/17246). [#17249](https://github.com/ClickHouse/ClickHouse/pull/17249) ([Amos Bird](https://github.com/amosbird)).
- Fix possible wrong index analysis when the types of the index comparison are different. This fixes [#17122](https://github.com/ClickHouse/ClickHouse/issues/17122). [#17145](https://github.com/ClickHouse/ClickHouse/pull/17145) ([Amos Bird](https://github.com/amosbird)).
- Fix ColumnConst comparison which leads to crash. This fixed [#17088](https://github.com/ClickHouse/ClickHouse/issues/17088) . [#17135](https://github.com/ClickHouse/ClickHouse/pull/17135) ([Amos Bird](https://github.com/amosbird)).
- Multiple fixed for MaterializeMySQL (experimental feature). Fixes [#16923](https://github.com/ClickHouse/ClickHouse/issues/16923) Fixes [#15883](https://github.com/ClickHouse/ClickHouse/issues/15883) Fix MaterializeMySQL SYNC failure when the modify MySQL binlog\_checksum. [#17091](https://github.com/ClickHouse/ClickHouse/pull/17091) ([Winter Zhang](https://github.com/zhang2014)).
- Fix bug when `ON CLUSTER` queries may hang forever for non-leader ReplicatedMergeTreeTables. [#17089](https://github.com/ClickHouse/ClickHouse/pull/17089) ([alesapin](https://github.com/alesapin)).
- Fixed crash on `CREATE TABLE ... AS some_table` query when `some_table` was created `AS table_function()` Fixes [#16944](https://github.com/ClickHouse/ClickHouse/issues/16944). [#17072](https://github.com/ClickHouse/ClickHouse/pull/17072) ([tavplubix](https://github.com/tavplubix)).
- Bug unfinished implementation for funciton fuzzBits, related issue: [#16980](https://github.com/ClickHouse/ClickHouse/issues/16980). [#17051](https://github.com/ClickHouse/ClickHouse/pull/17051) ([hexiaoting](https://github.com/hexiaoting)).
- Fix LLVM's libunwind in the case when CFA register is RAX. This is the [bug](https://bugs.llvm.org/show_bug.cgi?id=48186) in [LLVM's libunwind](https://github.com/llvm/llvm-project/tree/master/libunwind). We already have workarounds for this bug. [#17046](https://github.com/ClickHouse/ClickHouse/pull/17046) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Avoid unnecessary network errors for remote queries which may be cancelled while execution, like queries with `LIMIT`. [#17006](https://github.com/ClickHouse/ClickHouse/pull/17006) ([Azat Khuzhin](https://github.com/azat)).
- Fix `optimize_distributed_group_by_sharding_key` setting (that is disabled by default) for query with OFFSET only. [#16996](https://github.com/ClickHouse/ClickHouse/pull/16996) ([Azat Khuzhin](https://github.com/azat)).
- Fix for Merge tables over Distributed tables with JOIN. [#16993](https://github.com/ClickHouse/ClickHouse/pull/16993) ([Azat Khuzhin](https://github.com/azat)).
- Fixed wrong result in big integers (128, 256 bit) when casting from double. Big integers support is experimental. [#16986](https://github.com/ClickHouse/ClickHouse/pull/16986) ([Mike](https://github.com/myrrc)).
- Fix possible server crash after `ALTER TABLE ... MODIFY COLUMN ... NewType` when `SELECT` have `WHERE` expression on altering column and alter does not finished yet. [#16968](https://github.com/ClickHouse/ClickHouse/pull/16968) ([Amos Bird](https://github.com/amosbird)).
- Blame info was not calculated correctly in `clickhouse-git-import`. [#16959](https://github.com/ClickHouse/ClickHouse/pull/16959) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix order by optimization with monotonous functions. Fixes [#16107](https://github.com/ClickHouse/ClickHouse/issues/16107). [#16956](https://github.com/ClickHouse/ClickHouse/pull/16956) ([Anton Popov](https://github.com/CurtizJ)).