title_wip

#### Performance Improvement[​](#performance-improvement-1 "Direct link to Performance Improvement")

- Optimized memory usage for values of index granularity if granularity is constant for part. Added an ability to always select constant granularity for part (setting `use_const_adaptive_granularity`), which helps to ensure that it is always optimized in memory. It helps in large workloads (trillions of rows in shared storage) to avoid constantly growing memory usage by metadata (values of index granularity) of data parts. [#71786](https://github.com/ClickHouse/ClickHouse/pull/71786) ([Anton Popov](https://github.com/CurtizJ)).
- Now we don't copy input blocks columns for `join_algorithm = 'parallel_hash'` when distribute them between threads for parallel processing. [#67782](https://github.com/ClickHouse/ClickHouse/pull/67782) ([Nikita Taranov](https://github.com/nickitat)).
- Optimized `Replacing` merge algorithm for non-intersecting parts. [#70977](https://github.com/ClickHouse/ClickHouse/pull/70977) ([Anton Popov](https://github.com/CurtizJ)).
- Do not list detached parts from readonly and write-once disks for metrics and system.detached\_parts. [#71086](https://github.com/ClickHouse/ClickHouse/pull/71086) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Do not calculate heavy asynchronous metrics by default. The feature was introduced in [#40332](https://github.com/ClickHouse/ClickHouse/issues/40332), but it isn't good to have a heavy background job that is needed for only a single customer. [#71087](https://github.com/ClickHouse/ClickHouse/pull/71087) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- For the `plain_rewritable` disks: Do not call the object storage API when listing directories, as this may be cost-inefficient. Instead, store the list of filenames in the memory. The trade-offs are increased initial load time and memory required to store filenames. [#70823](https://github.com/ClickHouse/ClickHouse/pull/70823) ([Julia Kartseva](https://github.com/jkartseva)).
- Improve the performance and accuracy of `system.query_metric_log` collection interval by reducing the critical region. [#71473](https://github.com/ClickHouse/ClickHouse/pull/71473) ([Pablo Marcos](https://github.com/pamarcos)).
- Read-in-order optimization via generating virtual rows, so less data would be read during merge sort especially useful when multiple parts exist. [#62125](https://github.com/ClickHouse/ClickHouse/pull/62125) ([Shichao Jin](https://github.com/jsc0218)).
- Added server setting `async_load_system_database` that allows the server to start with not fully loaded system database. This helps to start ClickHouse faster if there are many system tables. [#69847](https://github.com/ClickHouse/ClickHouse/pull/69847) ([Sergei Trifonov](https://github.com/serxa)).
- Add `--threads` parameter to `clickhouse-compressor`, which allows to compress data in parallel. [#70860](https://github.com/ClickHouse/ClickHouse/pull/70860) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Added a setting `prewarm_mark_cache` which enables loading of marks to mark cache on inserts, merges, fetches of parts and on startup of the table. [#71053](https://github.com/ClickHouse/ClickHouse/pull/71053) ([Anton Popov](https://github.com/CurtizJ)).
- Shrink to fit index\_granularity array in memory to reduce memory footprint for MergeTree table engines family. [#71595](https://github.com/ClickHouse/ClickHouse/pull/71595) ([alesapin](https://github.com/alesapin)).
- Turn off filesystem cache setting `boundary_alignment` for non-disk read, which improves performance of reading from standalone remote files with caching. [#71827](https://github.com/ClickHouse/ClickHouse/pull/71827) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Queries like `SELECT * FROM table LIMIT ...` used to load part indexes even though they were not used. [#71866](https://github.com/ClickHouse/ClickHouse/pull/71866) ([Alexander Gololobov](https://github.com/davenger)).
- Enable `parallel_replicas_local_plan` by default. Building a full-fledged local plan on the query initiator improves parallel replicas performance with less resource consumption, provides opportunities to apply more query optimizations. [#70171](https://github.com/ClickHouse/ClickHouse/pull/70171) ([Igor Nikonov](https://github.com/devcrafter)).

#### Improvement[​](#improvement-1 "Direct link to Improvement")