v25.8 Changelog for Cloud

### System tables and observability[​](#system-tables-and-observability "Direct link to System tables and observability")

- Add pressure metrics to ClickHouse async metrics. [#80779](https://github.com/ClickHouse/ClickHouse/pull/80779) ([Xander Garbett](https://github.com/Garbett1)).
- Add metrics `MarkCacheEvictedBytes`, `MarkCacheEvictedMarks`, `MarkCacheEvictedFiles` for tracking evictions from the mark cache. (issue [#60989](https://github.com/ClickHouse/ClickHouse/issues/60989)). [#80799](https://github.com/ClickHouse/ClickHouse/pull/80799) ([Shivji Kumar Jha](https://github.com/shiv4289)).
- The `system.formats` table now contains extended information about formats, such as HTTP content type, the capabilities of schema inference, etc. [#81505](https://github.com/ClickHouse/ClickHouse/pull/81505) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add support for clearing all warnings from the `system.warnings` table using `TRUNCATE TABLE system.warnings`. [#82087](https://github.com/ClickHouse/ClickHouse/pull/82087) ([Vladimir Cherkasov](https://github.com/vdimir)).
- List the licenses of rust crates in `system.licenses`. [#82440](https://github.com/ClickHouse/ClickHouse/pull/82440) ([Raúl Marín](https://github.com/Algunenano)).
- Estimate complex cnf/dnf, for example, `(a < 1 and a > 0) or b = 3`, by statistics. [#82663](https://github.com/ClickHouse/ClickHouse/pull/82663) ([Han Fei](https://github.com/hanfei1991)).
- In some cases, we need to have multiple dimensions to our metrics. For example, counting failed merges or mutations by error codes rather than having a single counter. [#83030](https://github.com/ClickHouse/ClickHouse/pull/83030) ([Miсhael Stetsyuk](https://github.com/mstetsyuk)).
- Add process resource metrics (such as `UserTimeMicroseconds`, `SystemTimeMicroseconds`, `RealTimeMicroseconds`) to part\_log profile events for `MergeParts` entries. [#83460](https://github.com/ClickHouse/ClickHouse/pull/83460) ([Vladimir Cherkasov](https://github.com/vdimir)).
- Cgroup-level and system-wide metrics are reported now altogether. Cgroup-level metrics have names `CGroup<Metric>` and OS-level metrics (collected from procfs) have names `OS<Metric>`. [#84317](https://github.com/ClickHouse/ClickHouse/pull/84317) ([Nikita Taranov](https://github.com/nickitat)).
- Add dimensional metrics to monitor the size of concurrent bounded queues, labeled by queue type and instance ID for better observability. [#84675](https://github.com/ClickHouse/ClickHouse/pull/84675) ([Miсhael Stetsyuk](https://github.com/mstetsyuk)).
- The [`system.columns`](/docs/operations/system-tables/columns) table now provides `column` as an alias for the existing `name` column. [#84695](https://github.com/ClickHouse/ClickHouse/pull/84695) ([Yunchi Pang](https://github.com/yunchipang)).
- Add format string column to `system.errors`. This column is needed to group by the same error type in alerting rules. [#84776](https://github.com/ClickHouse/ClickHouse/pull/84776) ([Miсhael Stetsyuk](https://github.com/mstetsyuk)).
- Make limits tunable for Async Log and add introspection. [#85105](https://github.com/ClickHouse/ClickHouse/pull/85105) ([Raúl Marín](https://github.com/Algunenano)).
- Ignore `UNKNOWN_DATABASE` while obtaining table columns sizes for system.columns. [#85632](https://github.com/ClickHouse/ClickHouse/pull/85632) ([Azat Khuzhin](https://github.com/azat)).

### Database engines[​](#database-engines "Direct link to Database engines")

### System and internal improvements[​](#system-and-internal-improvements "Direct link to System and internal improvements")

- Fix attaching databases with read-only remote disks by manually adding table UUIDs to the DatabaseCatalog. [#82670](https://github.com/ClickHouse/ClickHouse/pull/82670) ([Tuan Pham Anh](https://github.com/tuanpach)).
- Improve DDL task handling when `distributed_ddl_output_mode='*_only_active'` by not waiting for new or recovered replicas that have replication lag exceeding `max_replication_lag_to_enqueue`. This helps avoid `DDL task is not finished on some hosts` errors when a new replica becomes active after initialization or recovery but has accumulated a large replication log. Also implemented `SYSTEM SYNC DATABASE REPLICA STRICT` query that waits for the replication log to fall below `max_replication_lag_to_enqueue`. [#83302](https://github.com/ClickHouse/ClickHouse/pull/83302) ([Alexander Tokmakov](https://github.com/tavplubix)).
- Chang SystemLogs shutdown order to occur after ordinary tables (and before system tables, instead of before ordinary tables). [#83134](https://github.com/ClickHouse/ClickHouse/pull/83134) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Add server setting `logs_to_keep` for replicated database settings, allowing configuration of the default `logs_to_keep` parameter for replicated databases. Lower values reduce the number of ZooKeeper nodes (especially beneficial when there are many databases), while higher values allow missing replicas to catch up after longer periods of downtime. [#84183](https://github.com/ClickHouse/ClickHouse/pull/84183) ([Alexey Khatskevich](https://github.com/Khatskevich)).
- Change the default value of the Replicated database setting `max_retries_before_automatic_recovery` to 10, enabling faster recovery in some cases. [#84369](https://github.com/ClickHouse/ClickHouse/pull/84369) ([Alexander Tokmakov](https://github.com/tavplubix)).
- Optimize non-append Refreshable Materialized View DDL operations in Replicated databases by skipping creation and renaming of old temporary tables. [#84858](https://github.com/ClickHouse/ClickHouse/pull/84858) ([Tuan Pham Anh](https://github.com/tuanpach)).

### Replication and synchronization[​](#replication-and-synchronization "Direct link to Replication and synchronization")

### SystemAndInternalImprovements[​](#systemandinternalimprovements "Direct link to SystemAndInternalImprovements")

- Improve `SYSTEM RESTART REPLICA` to retry table creation when ZooKeeper connection issues occur, preventing tables from being forgotten. [#82616](https://github.com/ClickHouse/ClickHouse/pull/82616) ([Nikolay Degterinsky](https://github.com/evillique)).
- Add UUID validation in `ReplicatedMergeTree::executeMetadataAlter` to prevent incorrect table definitions when tables are exchanged between getting the StorageID and calling `IDatabase::alterTable`. [#82666](https://github.com/ClickHouse/ClickHouse/pull/82666) ([Nikolay Degterinsky](https://github.com/evillique)).
- Remove experimental `send_metadata` logic related to experimental zero-copy replication. This code was never used, unsupported, and likely broken, with no tests to verify its functionality. [#82508](https://github.com/ClickHouse/ClickHouse/pull/82508) ([alesapin](https://github.com/alesapin)).
- Add support for macro expansion in `remote_fs_zero_copy_zookeeper_path`. [#85437](https://github.com/ClickHouse/ClickHouse/pull/85437) ([Mikhail Koviazin](https://github.com/mkmkme)).

### Functions and expressions[​](#functions-and-expressions "Direct link to Functions and expressions")