title_wip

#### New Feature[​](#new-feature-9 "Direct link to New Feature")

- Support reading and writing backups as `tar` (in addition to `zip`). [#59535](https://github.com/ClickHouse/ClickHouse/pull/59535) ([josh-hildred](https://github.com/josh-hildred)).
- Implemented support for S3 Express buckets. [#59965](https://github.com/ClickHouse/ClickHouse/pull/59965) ([Nikita Taranov](https://github.com/nickitat)).
- Allow to attach parts from a different disk (using copy instead of hard link). [#60112](https://github.com/ClickHouse/ClickHouse/pull/60112) ([Unalian](https://github.com/Unalian)).
- Size-capped `Memory` tables: controlled by their settings, `min_bytes_to_keep, max_bytes_to_keep, min_rows_to_keep` and `max_rows_to_keep`. [#60612](https://github.com/ClickHouse/ClickHouse/pull/60612) ([Jake Bamrah](https://github.com/JakeBamrah)).
- Separate limits on number of waiting and executing queries. Added new server setting `max_waiting_queries` that limits the number of queries waiting due to `async_load_databases`. Existing limits on number of executing queries no longer count waiting queries. [#61053](https://github.com/ClickHouse/ClickHouse/pull/61053) ([Sergei Trifonov](https://github.com/serxa)).
- Added a table `system.keywords` which contains all the keywords from parser. Mostly needed and will be used for better fuzzing and syntax highlighting. [#51808](https://github.com/ClickHouse/ClickHouse/pull/51808) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- Add support for `ATTACH PARTITION ALL`. [#61107](https://github.com/ClickHouse/ClickHouse/pull/61107) ([Kirill Nikiforov](https://github.com/allmazz)).
- Add a new function, `getClientHTTPHeader`. This closes [#54665](https://github.com/ClickHouse/ClickHouse/issues/54665). Co-authored with @lingtaolf. [#61820](https://github.com/ClickHouse/ClickHouse/pull/61820) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add `generate_series` as a table function (compatibility alias for PostgreSQL to the existing `numbers` function). This function generates table with an arithmetic progression with natural numbers. [#59390](https://github.com/ClickHouse/ClickHouse/pull/59390) ([divanik](https://github.com/divanik)).
- A mode for `topK`/`topkWeighed` support mode, which return count of values and its error. [#54508](https://github.com/ClickHouse/ClickHouse/pull/54508) ([UnamedRus](https://github.com/UnamedRus)).
- Added function `toMillisecond` which returns the millisecond component for values of type`DateTime` or `DateTime64`. [#60281](https://github.com/ClickHouse/ClickHouse/pull/60281) ([Shaun Struwig](https://github.com/Blargian)).
- Allow configuring HTTP redirect handlers for clickhouse-server. For example, you can make `/` redirect to the Play UI. [#60390](https://github.com/ClickHouse/ClickHouse/pull/60390) ([Alexey Milovidov](https://github.com/alexey-milovidov)).

#### Performance Improvement[​](#performance-improvement-9 "Direct link to Performance Improvement")

- Optimized function `dotProduct` to omit unnecessary and expensive memory copies. [#60928](https://github.com/ClickHouse/ClickHouse/pull/60928) ([Robert Schulze](https://github.com/rschu1ze)).
- 30x faster printing for 256-bit integers. [#61100](https://github.com/ClickHouse/ClickHouse/pull/61100) ([Raúl Marín](https://github.com/Algunenano)).
- If the table's primary key contains mostly useless columns, don't keep them in memory. This is controlled by a new setting `primary_key_ratio_of_unique_prefix_values_to_skip_suffix_columns` with the value `0.9` by default, which means: for a composite primary key, if a column changes its value for at least 0.9 of all the times, the next columns after it will be not loaded. [#60255](https://github.com/ClickHouse/ClickHouse/pull/60255) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Improve the performance of serialized aggregation methods when involving multiple `Nullable` columns. [#55809](https://github.com/ClickHouse/ClickHouse/pull/55809) ([Amos Bird](https://github.com/amosbird)).
- Lazy builds JSON's output to improve performance of ALL JOIN. [#58278](https://github.com/ClickHouse/ClickHouse/pull/58278) ([LiuNeng](https://github.com/liuneng1994)).
- Make HTTP/HTTPS connections with external services, such as AWS S3 reusable for all use cases. Even when the response is 3xx or 4xx. [#58845](https://github.com/ClickHouse/ClickHouse/pull/58845) ([Sema Checherinda](https://github.com/CheSema)).
- Improvements to aggregate functions `argMin` / `argMax` / `any` / `anyLast` / `anyHeavy`, as well as `ORDER BY {u8/u16/u32/u64/i8/i16/u32/i64) LIMIT 1` queries. [#58640](https://github.com/ClickHouse/ClickHouse/pull/58640) ([Raúl Marín](https://github.com/Algunenano)).
- Trivial optimization for column's filter. Peak memory can be reduced to 44% of the original in some cases. [#59698](https://github.com/ClickHouse/ClickHouse/pull/59698) ([李扬](https://github.com/taiyang-li)).
- Execute `multiIf` function in a columnar fashion when the result type's underlying type is a number. [#60384](https://github.com/ClickHouse/ClickHouse/pull/60384) ([李扬](https://github.com/taiyang-li)).
- Faster (almost 2x) mutexes. [#60823](https://github.com/ClickHouse/ClickHouse/pull/60823) ([Azat Khuzhin](https://github.com/azat)).
- Drain multiple connections in parallel when a distributed query is finishing. [#60845](https://github.com/ClickHouse/ClickHouse/pull/60845) ([lizhuoyu5](https://github.com/lzydmxy)).
- Optimize data movement between columns of a Nullable number or a Nullable string, which improves some micro-benchmarks. [#60846](https://github.com/ClickHouse/ClickHouse/pull/60846) ([李扬](https://github.com/taiyang-li)).
- Operations with the filesystem cache will suffer less from the lock contention. [#61066](https://github.com/ClickHouse/ClickHouse/pull/61066) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Optimize array join and other JOINs by preventing a wrong compiler's optimization. Close [#61074](https://github.com/ClickHouse/ClickHouse/issues/61074). [#61075](https://github.com/ClickHouse/ClickHouse/pull/61075) ([李扬](https://github.com/taiyang-li)).
- If a query with a syntax error contained the `COLUMNS` matcher with a regular expression, the regular expression was compiled each time during the parser's backtracking, instead of being compiled once. This was a fundamental error. The compiled regexp was put to AST. But the letter A in AST means "abstract" which means it should not contain heavyweight objects. Parts of AST can be created and discarded during parsing, including a large number of backtracking. This leads to slowness on the parsing side and consequently allows DoS by a readonly user. But the main problem is that it prevents progress in fuzzers. [#61543](https://github.com/ClickHouse/ClickHouse/pull/61543) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add a new analyzer pass to optimize the IN operator for a single value. [#61564](https://github.com/ClickHouse/ClickHouse/pull/61564) ([LiuNeng](https://github.com/liuneng1994)).
- DNSResolver shuffles set of resolved IPs which is needed to uniformly utilize multiple endpoints of AWS S3. [#60965](https://github.com/ClickHouse/ClickHouse/pull/60965) ([Sema Checherinda](https://github.com/CheSema)).

#### Experimental Feature[​](#experimental-feature-7 "Direct link to Experimental Feature")