title_wip

#### Experimental Feature[​](#experimental-feature-9 "Direct link to Experimental Feature")

- Functions for text classification: language and charset detection. See [#23271](https://github.com/ClickHouse/ClickHouse/issues/23271). [#33314](https://github.com/ClickHouse/ClickHouse/pull/33314) ([Nikolay Degterinsky](https://github.com/evillique)).
- Add memory overcommit to `MemoryTracker`. Added `guaranteed` settings for memory limits which represent soft memory limits. In case when hard memory limit is reached, `MemoryTracker` tries to cancel the most overcommited query. New setting `memory_usage_overcommit_max_wait_microseconds` specifies how long queries may wait another query to stop. Closes [#28375](https://github.com/ClickHouse/ClickHouse/issues/28375). [#31182](https://github.com/ClickHouse/ClickHouse/pull/31182) ([Dmitry Novik](https://github.com/novikd)).
- Enable stream to table join in WindowView. [#33729](https://github.com/ClickHouse/ClickHouse/pull/33729) ([vxider](https://github.com/Vxider)).
- Support `SET`, `YEAR`, `TIME` and `GEOMETRY` data types in `MaterializedMySQL` (experimental feature). Fixes [#18091](https://github.com/ClickHouse/ClickHouse/issues/18091), [#21536](https://github.com/ClickHouse/ClickHouse/issues/21536), [#26361](https://github.com/ClickHouse/ClickHouse/issues/26361). [#33429](https://github.com/ClickHouse/ClickHouse/pull/33429) ([zzsmdfj](https://github.com/zzsmdfj)).
- Fix various issues when projection is enabled by default. Each issue is described in separate commit. This is for [#33678](https://github.com/ClickHouse/ClickHouse/issues/33678) . This fixes [#34273](https://github.com/ClickHouse/ClickHouse/issues/34273). [#34305](https://github.com/ClickHouse/ClickHouse/pull/34305) ([Amos Bird](https://github.com/amosbird)).

#### Performance Improvement[​](#performance-improvement-10 "Direct link to Performance Improvement")

- Support `optimize_read_in_order` if prefix of sorting key is already sorted. E.g. if we have sorting key `ORDER BY (a, b)` in table and query with `WHERE a = const ORDER BY b` clauses, now it will be applied reading in order of sorting key instead of full sort. [#32748](https://github.com/ClickHouse/ClickHouse/pull/32748) ([Anton Popov](https://github.com/CurtizJ)).
- Improve performance of partitioned insert into table functions `URL`, `S3`, `File`, `HDFS`. Closes [#34348](https://github.com/ClickHouse/ClickHouse/issues/34348). [#34510](https://github.com/ClickHouse/ClickHouse/pull/34510) ([Maksim Kita](https://github.com/kitaisreal)).
- Multiple performance improvements of clickhouse-keeper. [#34484](https://github.com/ClickHouse/ClickHouse/pull/34484) [#34587](https://github.com/ClickHouse/ClickHouse/pull/34587) ([zhanglistar](https://github.com/zhanglistar)).
- `FlatDictionary` improve performance of dictionary data load. [#33871](https://github.com/ClickHouse/ClickHouse/pull/33871) ([Maksim Kita](https://github.com/kitaisreal)).
- Improve performance of `mapPopulateSeries` function. Closes [#33944](https://github.com/ClickHouse/ClickHouse/issues/33944). [#34318](https://github.com/ClickHouse/ClickHouse/pull/34318) ([Maksim Kita](https://github.com/kitaisreal)).
- `_file` and `_path` virtual columns (in file-like table engines) are made `LowCardinality` - it will make queries for multiple files faster. Closes [#34300](https://github.com/ClickHouse/ClickHouse/issues/34300). [#34317](https://github.com/ClickHouse/ClickHouse/pull/34317) ([flynn](https://github.com/ucasfl)).
- Speed up loading of data parts. It was not parallelized before: the setting `part_loading_threads` did not have effect. See [#4699](https://github.com/ClickHouse/ClickHouse/issues/4699). [#34310](https://github.com/ClickHouse/ClickHouse/pull/34310) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Improve performance of `LineAsString` format. This closes [#34303](https://github.com/ClickHouse/ClickHouse/issues/34303). [#34306](https://github.com/ClickHouse/ClickHouse/pull/34306) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Optimize `quantilesExact{Low,High}` to use `nth_element` instead of `sort`. [#34287](https://github.com/ClickHouse/ClickHouse/pull/34287) ([Danila Kutenin](https://github.com/danlark1)).
- Slightly improve performance of `Regexp` format. [#34202](https://github.com/ClickHouse/ClickHouse/pull/34202) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Minor improvement for analysis of scalar subqueries. [#34128](https://github.com/ClickHouse/ClickHouse/pull/34128) ([Federico Rodriguez](https://github.com/fedrod)).
- Make ORDER BY tuple almost as fast as ORDER BY columns. We have special optimizations for multiple column ORDER BY: <https://github.com/ClickHouse/ClickHouse/pull/10831> . It's beneficial to also apply to tuple columns. [#34060](https://github.com/ClickHouse/ClickHouse/pull/34060) ([Amos Bird](https://github.com/amosbird)).
- Rework and reintroduce the scalar subqueries cache to Materialized Views execution. [#33958](https://github.com/ClickHouse/ClickHouse/pull/33958) ([Raúl Marín](https://github.com/Algunenano)).
- Slightly improve performance of `ORDER BY` by adding x86-64 AVX-512 support for `memcmpSmall` functions to accelerate memory comparison. It works only if you compile ClickHouse by yourself. [#33706](https://github.com/ClickHouse/ClickHouse/pull/33706) ([hanqf-git](https://github.com/hanqf-git)).
- Improve `range_hashed` dictionary performance if for key there are a lot of intervals. Fixes [#23821](https://github.com/ClickHouse/ClickHouse/issues/23821). [#33516](https://github.com/ClickHouse/ClickHouse/pull/33516) ([Maksim Kita](https://github.com/kitaisreal)).
- For inserts and merges into S3, write files in parallel whenever possible (TODO: check if it's merged). [#33291](https://github.com/ClickHouse/ClickHouse/pull/33291) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Improve `clickhouse-keeper` performance and fix several memory leaks in NuRaft library. [#33329](https://github.com/ClickHouse/ClickHouse/pull/33329) ([alesapin](https://github.com/alesapin)).

#### Improvement[​](#improvement-10 "Direct link to Improvement")