Changelog 2026

- Add component name to `system.aggregated_zookeeper_log`. [#95882](https://github.com/ClickHouse/ClickHouse/pull/95882) ([Antonio Andelic](https://github.com/antonio2368)).
- Skip object storage reads when querying `DeltaLake` tables from `system.tables`. [#95899](https://github.com/ClickHouse/ClickHouse/pull/95899) ([Antonio Andelic](https://github.com/antonio2368)).
- Enable `enable_max_bytes_limit_for_min_age_to_force_merge` by default if the `compatibility` setting is `26.2` or higher. [#95917](https://github.com/ClickHouse/ClickHouse/pull/95917) ([Christoph Wurm](https://github.com/cwurm)).
- Delta Lake is now available on macOS. Closes #95979. [#95985](https://github.com/ClickHouse/ClickHouse/pull/95985) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- In previous versions, when combining conflicting ALTER expressions with UPDATE and RENAME COLUMN, a logical error was thrown instead of a proper exception. Closes [#70678](https://github.com/ClickHouse/ClickHouse/issues/70678). [#96022](https://github.com/ClickHouse/ClickHouse/pull/96022) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Improve the help output for all ClickHouse applications and add a --no-sudo option with a few fixes. This is a continuation of [#58244](https://github.com/ClickHouse/ClickHouse/issues/58244) from [Ilya Yatsishin](https://github.com/qoega). [#96025](https://github.com/ClickHouse/ClickHouse/pull/96025) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add `distanceCosine` alias for `cosineDistance` because all other distance functions already have alias of this form. [#96065](https://github.com/ClickHouse/ClickHouse/pull/96065) ([Raufs Dunamalijevs](https://github.com/rienath)).
- Add support for the `with_data` Keeper extension to improve table fetching in Database Replicated. [#96090](https://github.com/ClickHouse/ClickHouse/pull/96090) ([Nikolay Degterinsky](https://github.com/evillique)).
- Update chdig to [v26.2.1](https://github.com/azat/chdig/releases/tag/v26.2.1) (new features and MacOS support). [#96113](https://github.com/ClickHouse/ClickHouse/pull/96113) ([Azat Khuzhin](https://github.com/azat)).
- Improve filter pushdown for `numbers` and `primes`. ClickHouse can now derive conservative value bounds from `WHERE` conditions when exact bounds cannot be derived, and restrict sequence generation accordingly (for example, for `WHERE number % 5 < 2 AND number > 100 AND number < 300`, ClickHouse will only generate numbers between 100 and 300, then apply the predicate), avoiding unbounded scans. Closes [#84853](https://github.com/ClickHouse/ClickHouse/issues/84853). Closes [#93913](https://github.com/ClickHouse/ClickHouse/issues/93913). [#96115](https://github.com/ClickHouse/ClickHouse/pull/96115) ([Nihal Z. Miaji](https://github.com/nihalzp)).
- The formatter previously wrapped SELECT in parentheses when a `COMMENT` clause was present to disambiguate parsing. Instead, output `COMMENT` before `AS SELECT`, which eliminates the ambiguity without parentheses. [#96293](https://github.com/ClickHouse/ClickHouse/pull/96293) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- The `allow_impersonate_user` config setting is now located inside the `access_control_improvements` section rather than being a standalone server setting. [#96451](https://github.com/ClickHouse/ClickHouse/pull/96451) ([Vitaly Baranov](https://github.com/vitlibar)).
- Make `core_dump.size_limit` configuration setting hot-reloadable, to avoid having to restart servers for configuration changes to take place. [#96524](https://github.com/ClickHouse/ClickHouse/pull/96524) ([Miсhael Stetsyuk](https://github.com/mstetsyuk)).
- Improves CPU and real-time profiler interoperability with socket timeouts. [#96601](https://github.com/ClickHouse/ClickHouse/pull/96601) ([Sergei Trifonov](https://github.com/serxa)).
- Prevent the resurrection of dropped data if ADD COLUMN is run quickly after the DROP COLUMN mutation. [#96713](https://github.com/ClickHouse/ClickHouse/pull/96713) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Change `function_id` type in `system.instrumentation` from LowCardinality(Int32) to Int32. [#96726](https://github.com/ClickHouse/ClickHouse/pull/96726) (Copilot).
- Synchronous waiting for mutations will respect query cancellation and time limits. [#96756](https://github.com/ClickHouse/ClickHouse/pull/96756) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Added system command `SYSTEM RELOAD DELTA KERNEL TRACING <level>` to be able to change delta-kernel logging, which can be useful for debugging. [#96763](https://github.com/ClickHouse/ClickHouse/pull/96763) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Filtering by IP address family, i.e. `dns_allow_resolve_names_to_ipv4/ipv6` settings, are applied even if DNS cache is disabled. [#96810](https://github.com/ClickHouse/ClickHouse/pull/96810) ([c-end](https://github.com/c-end)).
- Better jemalloc introspection. [#96840](https://github.com/ClickHouse/ClickHouse/pull/96840) ([Azat Khuzhin](https://github.com/azat)).
- Fix `/play` Web UI throwing `QUERY_CACHE_USED_WITH_SYSTEM_TABLE` when querying system tables. [#96869](https://github.com/ClickHouse/ClickHouse/pull/96869) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Improve Web UI: change favicon to indicate running query state; display errors from auxiliary queries (loading databases and tables) instead of silently ignoring them. Closes [#85055](https://github.com/ClickHouse/ClickHouse/issues/85055). [#96883](https://github.com/ClickHouse/ClickHouse/pull/96883) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Make the left panel in `/play` UI clickable to toggle the database list. [#96884](https://github.com/ClickHouse/ClickHouse/pull/96884) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- `DROP DATABASE` now drops tables in reverse dependency order, improving crash-safety when the database contains tables with loading dependencies (e.g. `Distributed` tables using `joinGet`). [#97057](https://github.com/ClickHouse/ClickHouse/pull/97057) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Bump yaml-cpp to prevent skipping invalid YAML. [#97333](https://github.com/ClickHouse/ClickHouse/pull/97333) ([Azat Khuzhin](https://github.com/azat)).
- Show a loading indicator in the `play.html` sidebar while tables are being fetched. [#97531](https://github.com/ClickHouse/ClickHouse/pull/97531) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add a copy-to-clipboard button for raw query results in the built-in web UI (play.html). [#97532](https://github.com/ClickHouse/ClickHouse/pull/97532) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix query obfuscator (`clickhouse-format --obfuscate`) to produce parseable SQL in more cases. [#97584](https://github.com/ClickHouse/ClickHouse/pull/97584) ([Alexey Milovidov](https://github.com/alexey-milovidov)).