2021 Changelog

- Case-insensitive compression methods for table functions. Also fixed LZMA compression method which was checked in upper case. [#21416](https://github.com/ClickHouse/ClickHouse/pull/21416) ([Vladimir Chebotarev](https://github.com/excitoon)).
- Add two settings to delay or throw error during insertion when there are too many inactive parts. This is useful when server fails to clean up parts quickly enough. [#20178](https://github.com/ClickHouse/ClickHouse/pull/20178) ([Amos Bird](https://github.com/amosbird)).
- Provide better compatibility for mysql clients. 1. mysql jdbc 2. mycli. [#21367](https://github.com/ClickHouse/ClickHouse/pull/21367) ([Amos Bird](https://github.com/amosbird)).
- Forbid to drop a column if it's referenced by materialized view. Closes [#21164](https://github.com/ClickHouse/ClickHouse/issues/21164). [#21303](https://github.com/ClickHouse/ClickHouse/pull/21303) ([flynn](https://github.com/ucasFL)).
- MySQL dictionary source will now retry unexpected connection failures (Lost connection to MySQL server during query) which sometimes happen on SSL/TLS connections. [#21237](https://github.com/ClickHouse/ClickHouse/pull/21237) ([Alexander Kazakov](https://github.com/Akazz)).
- Usability improvement: more consistent `DateTime64` parsing: recognize the case when unix timestamp with subsecond resolution is specified as scaled integer (like `1111111111222` instead of `1111111111.222`). This closes [#13194](https://github.com/ClickHouse/ClickHouse/issues/13194). [#21053](https://github.com/ClickHouse/ClickHouse/pull/21053) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Do only merging of sorted blocks on initiator with distributed\_group\_by\_no\_merge. [#20882](https://github.com/ClickHouse/ClickHouse/pull/20882) ([Azat Khuzhin](https://github.com/azat)).
- When loading config for mysql source ClickHouse will now randomize the list of replicas with the same priority to ensure the round-robin logics of picking mysql endpoint. This closes [#20629](https://github.com/ClickHouse/ClickHouse/issues/20629). [#20632](https://github.com/ClickHouse/ClickHouse/pull/20632) ([Alexander Kazakov](https://github.com/Akazz)).
- Function 'reinterpretAs(x, Type)' renamed into 'reinterpret(x, Type)'. [#20611](https://github.com/ClickHouse/ClickHouse/pull/20611) ([Maksim Kita](https://github.com/kitaisreal)).
- Support vhost for RabbitMQ engine [#20576](https://github.com/ClickHouse/ClickHouse/issues/20576). [#20596](https://github.com/ClickHouse/ClickHouse/pull/20596) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Improved serialization for data types combined of Arrays and Tuples. Improved matching enum data types to protobuf enum type. Fixed serialization of the `Map` data type. Omitted values are now set by default. [#20506](https://github.com/ClickHouse/ClickHouse/pull/20506) ([Vitaly Baranov](https://github.com/vitlibar)).
- Fixed race between execution of distributed DDL tasks and cleanup of DDL queue. Now DDL task cannot be removed from ZooKeeper if there are active workers. Fixes [#20016](https://github.com/ClickHouse/ClickHouse/issues/20016). [#20448](https://github.com/ClickHouse/ClickHouse/pull/20448) ([tavplubix](https://github.com/tavplubix)).
- Make FQDN and other DNS related functions work correctly in alpine images. [#20336](https://github.com/ClickHouse/ClickHouse/pull/20336) ([filimonov](https://github.com/filimonov)).
- Do not allow early constant folding of explicitly forbidden functions. [#20303](https://github.com/ClickHouse/ClickHouse/pull/20303) ([Azat Khuzhin](https://github.com/azat)).
- Implicit conversion from integer to Decimal type might succeeded if integer value doe not fit into Decimal type. Now it throws `ARGUMENT_OUT_OF_BOUND`. [#20232](https://github.com/ClickHouse/ClickHouse/pull/20232) ([tavplubix](https://github.com/tavplubix)).
- Lockless `SYSTEM FLUSH DISTRIBUTED`. [#20215](https://github.com/ClickHouse/ClickHouse/pull/20215) ([Azat Khuzhin](https://github.com/azat)).
- Normalize count(constant), sum(1) to count(). This is needed for projection query routing. [#20175](https://github.com/ClickHouse/ClickHouse/pull/20175) ([Amos Bird](https://github.com/amosbird)).
- Support all native integer types in bitmap functions. [#20171](https://github.com/ClickHouse/ClickHouse/pull/20171) ([Amos Bird](https://github.com/amosbird)).
- Updated `CacheDictionary`, `ComplexCacheDictionary`, `SSDCacheDictionary`, `SSDComplexKeyDictionary` to use LRUHashMap as underlying index. [#20164](https://github.com/ClickHouse/ClickHouse/pull/20164) ([Maksim Kita](https://github.com/kitaisreal)).
- The setting `access_management` is now configurable on startup by providing `CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT`, defaults to disabled (`0`) which was the prior value. [#20139](https://github.com/ClickHouse/ClickHouse/pull/20139) ([Marquitos](https://github.com/sonirico)).
- Fix toDateTime64(toDate()/toDateTime()) for DateTime64 - Implement DateTime64 clamping to match DateTime behaviour. [#20131](https://github.com/ClickHouse/ClickHouse/pull/20131) ([Azat Khuzhin](https://github.com/azat)).
- Quota improvements: SHOW TABLES is now considered as one query in the quota calculations, not two queries. SYSTEM queries now consume quota. Fix calculation of interval's end in quota consumption. [#20106](https://github.com/ClickHouse/ClickHouse/pull/20106) ([Vitaly Baranov](https://github.com/vitlibar)).
- Supports `path IN (set)` expressions for `system.zookeeper` table. [#20105](https://github.com/ClickHouse/ClickHouse/pull/20105) ([小路](https://github.com/nicelulu)).
- Show full details of `MaterializeMySQL` tables in `system.tables`. [#20051](https://github.com/ClickHouse/ClickHouse/pull/20051) ([Stig Bakken](https://github.com/stigsb)).
- Fix data race in executable dictionary that was possible only on misuse (when the script returns data ignoring its input). [#20045](https://github.com/ClickHouse/ClickHouse/pull/20045) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- The value of MYSQL\_OPT\_RECONNECT option can now be controlled by "opt\_reconnect" parameter in the config section of mysql replica. [#19998](https://github.com/ClickHouse/ClickHouse/pull/19998) ([Alexander Kazakov](https://github.com/Akazz)).
- If user calls `JSONExtract` function with `Float32` type requested, allow inaccurate conversion to the result type. For example the number `0.1` in JSON is double precision and is not representable in Float32, but the user still wants to get it. Previous versions return 0 for non-Nullable type and NULL for Nullable type to indicate that conversion is imprecise. The logic was 100% correct but it was surprising to users and leading to questions. This closes [#13962](https://github.com/ClickHouse/ClickHouse/issues/13962). [#19960](https://github.com/ClickHouse/ClickHouse/pull/19960) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Add conversion of block structure for INSERT into Distributed tables if it does not match. [#19947](https://github.com/ClickHouse/ClickHouse/pull/19947) ([Azat Khuzhin](https://github.com/azat)).
- Improvement for the `system.distributed_ddl_queue` table. Initialize MaxDDLEntryID to the last value after restarting. Before this PR, MaxDDLEntryID will remain zero until a new DDLTask is processed. [#19924](https://github.com/ClickHouse/ClickHouse/pull/19924) ([Amos Bird](https://github.com/amosbird)).
- Show `MaterializeMySQL` tables in `system.parts`. [#19770](https://github.com/ClickHouse/ClickHouse/pull/19770) ([Stig Bakken](https://github.com/stigsb)).
- Add separate config directive for `Buffer` profile. [#19721](https://github.com/ClickHouse/ClickHouse/pull/19721) ([Azat Khuzhin](https://github.com/azat)).
- Move conditions that are not related to JOIN to WHERE clause. [#18720](https://github.com/ClickHouse/ClickHouse/issues/18720). [#19685](https://github.com/ClickHouse/ClickHouse/pull/19685) ([hexiaoting](https://github.com/hexiaoting)).