2023 Changelog

#### Experimental Feature[​](#experimental-feature-2 "Direct link to Experimental Feature")

- Writing parquet files is 10x faster, it's multi-threaded now. Almost the same speed as reading. [#49367](https://github.com/ClickHouse/ClickHouse/pull/49367) ([Michael Kolupaev](https://github.com/al13n321)). This is controlled by the setting `output_format_parquet_use_custom_encoder` which is disabled by default, because the feature is non-ideal.
- Added support for [PRQL](https://prql-lang.org/) as a query language. [#50686](https://github.com/ClickHouse/ClickHouse/pull/50686) ([János Benjamin Antal](https://github.com/antaljanosbenjamin)).
- Allow to add disk name for custom disks. Previously custom disks would use an internal generated disk name. Now it will be possible with `disk = disk_<name>(...)` (e.g. disk will have name `name`) . [#51552](https://github.com/ClickHouse/ClickHouse/pull/51552) ([Kseniia Sumarokova](https://github.com/kssenii)). This syntax can be changed in this release.
- (experimental MaterializedMySQL) Fixed crash when `mysqlxx::Pool::Entry` is used after it was disconnected. [#52063](https://github.com/ClickHouse/ClickHouse/pull/52063) ([Val Doroshchuk](https://github.com/valbok)).
- (experimental MaterializedMySQL) `CREATE TABLE ... AS SELECT` .. is now supported in MaterializedMySQL. [#52067](https://github.com/ClickHouse/ClickHouse/pull/52067) ([Val Doroshchuk](https://github.com/valbok)).
- (experimental MaterializedMySQL) Introduced automatic conversion of text types to utf8 for MaterializedMySQL. [#52084](https://github.com/ClickHouse/ClickHouse/pull/52084) ([Val Doroshchuk](https://github.com/valbok)).
- (experimental MaterializedMySQL) Now unquoted UTF-8 strings are supported in DDL for MaterializedMySQL. [#52318](https://github.com/ClickHouse/ClickHouse/pull/52318) ([Val Doroshchuk](https://github.com/valbok)).
- (experimental MaterializedMySQL) Now double quoted comments are supported in MaterializedMySQL. [#52355](https://github.com/ClickHouse/ClickHouse/pull/52355) ([Val Doroshchuk](https://github.com/valbok)).
- Upgrade Intel QPL from v1.1.0 to v1.2.0 2. Upgrade Intel accel-config from v3.5 to v4.0 3. Fixed issue that Device IOTLB miss has big perf. impact for IAA accelerators. [#52180](https://github.com/ClickHouse/ClickHouse/pull/52180) ([jasperzhu](https://github.com/jinjunzh)).
- The `session_timezone` setting (new in version 23.6) is demoted to experimental. [#52445](https://github.com/ClickHouse/ClickHouse/pull/52445) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Support ZooKeeper `reconfig` command for ClickHouse Keeper with incremental reconfiguration which can be enabled via `keeper_server.enable_reconfiguration` setting. Support adding servers, removing servers, and changing server priorities. [#49450](https://github.com/ClickHouse/ClickHouse/pull/49450) ([Mike Kot](https://github.com/myrrc)). It is suspected that this feature is incomplete.

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-5 "Direct link to Build/Testing/Packaging Improvement")

- Add experimental ClickHouse builds for Linux RISC-V 64 to CI. [#31398](https://github.com/ClickHouse/ClickHouse/pull/31398) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add integration test check with the enabled Analyzer. [#50926](https://github.com/ClickHouse/ClickHouse/pull/50926) [#52210](https://github.com/ClickHouse/ClickHouse/pull/52210) ([Dmitry Novik](https://github.com/novikd)).
- Reproducible builds for Rust. [#52395](https://github.com/ClickHouse/ClickHouse/pull/52395) ([Azat Khuzhin](https://github.com/azat)).
- Update Cargo dependencies. [#51721](https://github.com/ClickHouse/ClickHouse/pull/51721) ([Raúl Marín](https://github.com/Algunenano)).
- Make the function `CHColumnToArrowColumn::fillArrowArrayWithArrayColumnData` to work with nullable arrays, which are not possible in ClickHouse, but needed for Gluten. [#52112](https://github.com/ClickHouse/ClickHouse/pull/52112) ([李扬](https://github.com/taiyang-li)).
- We've updated the CCTZ library to master, but there are no user-visible changes. [#52124](https://github.com/ClickHouse/ClickHouse/pull/52124) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- The `system.licenses` table now includes the hard-forked library Poco. This closes [#52066](https://github.com/ClickHouse/ClickHouse/issues/52066). [#52127](https://github.com/ClickHouse/ClickHouse/pull/52127) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Check that there are no cases of bad punctuation: whitespace before a comma like `Hello ,world` instead of `Hello, world`. [#52549](https://github.com/ClickHouse/ClickHouse/pull/52549) ([Alexey Milovidov](https://github.com/alexey-milovidov)).

#### Bug Fix (user-visible misbehavior in an official stable release)[​](#bug-fix-user-visible-misbehavior-in-an-official-stable-release-5 "Direct link to Bug Fix (user-visible misbehavior in an official stable release)")