v25.4 Changelog for Cloud

- It was discovered that concurrency control could lead to unfair CPU distribution between INSERTs and SELECTs. When all CPU slots are allocated unconditionally (w/o competition) to INSERTs with `max_threads` = 1 while SELECTs with high `max_threads` values suffer from poor performance due to using only a single thread. [#75941](https://github.com/ClickHouse/ClickHouse/pull/75941) ([Sergei Trifonov](https://github.com/serxa)).
- Trivial opt on wrapInNullable to avoid unnecessary null map allocation. [#76489](https://github.com/ClickHouse/ClickHouse/pull/76489) ([李扬](https://github.com/taiyang-li)).
- Improve min/max performance for Decimal32/Decimal64/DateTime64. [#76570](https://github.com/ClickHouse/ClickHouse/pull/76570) ([李扬](https://github.com/taiyang-li)).
- Actively evict data from the cache on parts removal. Do not let the cache grow to the maximum size if the amount of data is less. [#76641](https://github.com/ClickHouse/ClickHouse/pull/76641) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Query compilation (setting `compile_expressions`) now considers the machine type. This speeds up such queries significantly. [#76753](https://github.com/ClickHouse/ClickHouse/pull/76753) ([Robert Schulze](https://github.com/rschu1ze)).
- Optimize arraySort. [#76850](https://github.com/ClickHouse/ClickHouse/pull/76850) ([李扬](https://github.com/taiyang-li)).
- Speed-up building JOIN result by de-virtualizing calls to `col->insertFrom()`. [#77350](https://github.com/ClickHouse/ClickHouse/pull/77350) ([Alexander Gololobov](https://github.com/davenger)).
- Merge marks of the same part and write them to the query condition cache at one time to reduce the consumption of locks. [#77377](https://github.com/ClickHouse/ClickHouse/pull/77377) ([zhongyuankai](https://github.com/zhongyuankai)).
- Optimize order by single nullable or low-cardinality columns. [#77789](https://github.com/ClickHouse/ClickHouse/pull/77789) ([李扬](https://github.com/taiyang-li)).
- Disable `filesystem_cache_prefer_bigger_buffer_size` when the cache is used passively, such as for merges. [#77898](https://github.com/ClickHouse/ClickHouse/pull/77898) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Implement trivial count optimization for Iceberg. Now queries with `count()` and without any filters should be faster. Closes [#77639](https://github.com/ClickHouse/ClickHouse/issues/77639). [#78090](https://github.com/ClickHouse/ClickHouse/pull/78090) ([alesapin](https://github.com/alesapin)).
- Support Iceberg data pruning based on lower\_bound and uppert\_bound values for columns. Fixes [#77638](https://github.com/ClickHouse/ClickHouse/issues/77638). [#78242](https://github.com/ClickHouse/ClickHouse/pull/78242) ([alesapin](https://github.com/alesapin)).
- Optimize memory usage for NativeReader. [#78442](https://github.com/ClickHouse/ClickHouse/pull/78442) ([Azat Khuzhin](https://github.com/azat)).
- Trivial optimization: do not rewrite `count(if())` to countIf if `CAST` is required. Close [#78564](https://github.com/ClickHouse/ClickHouse/issues/78564). [#78565](https://github.com/ClickHouse/ClickHouse/pull/78565) ([李扬](https://github.com/taiyang-li)).