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sidebar_position: 1
sidebar_label: 2025
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# 2025 Changelog

### ClickHouse release v25.5.5.19-stable (c7635f09ae1) FIXME as compared to v25.5.4.38-stable (304d67604cf)

#### Improvement
* Backported in [#82594](https://github.com/ClickHouse/ClickHouse/issues/82594): Keeper improvement: add new config `keeper_server.cleanup_old_and_ignore_new_acl`. If enabled, all nodes will have their ACLs cleared while ACL for new requests will be ignored. If the goal is to completely remove ACL from nodes, it's important to leave the config enabled until a new snapshot is created. [#82496](https://github.com/ClickHouse/ClickHouse/pull/82496) ([Antonio Andelic](https://github.com/antonio2368)).
* Backported in [#82860](https://github.com/ClickHouse/ClickHouse/issues/82860): After https://github.com/ClickHouse/ClickHouse/pull/73834, the `X-ClickHouse-Progress` and `X-ClickHouse-Summary` header formats have been modified to omit zero values. This PR intends to return the previous behaviour for `X-ClickHouse-Summary` only, because it makes sense. [#82727](https://github.com/ClickHouse/ClickHouse/pull/82727) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
* Backported in [#82926](https://github.com/ClickHouse/ClickHouse/issues/82926): Keeper improvement: support specific permissions for world:anyone ACL. [#82755](https://github.com/ClickHouse/ClickHouse/pull/82755) ([Antonio Andelic](https://github.com/antonio2368)).

#### Bug Fix (user-visible misbehavior in an official stable release)
* Backported in [#82779](https://github.com/ClickHouse/ClickHouse/issues/82779): Fix filter analysis when only a constant alias column is used in the query. Fixes [#79448](https://github.com/ClickHouse/ClickHouse/issues/79448). [#82037](https://github.com/ClickHouse/ClickHouse/pull/82037) ([Dmitry Novik](https://github.com/novikd)).
* Backported in [#82559](https://github.com/ClickHouse/ClickHouse/issues/82559): Fix possible deadlock for remote queries when server is under memory pressure. [#82160](https://github.com/ClickHouse/ClickHouse/pull/82160) ([Kirill](https://github.com/kirillgarbar)).
* Backported in [#82688](https://github.com/ClickHouse/ClickHouse/issues/82688): Fix `LOGICAL_ERROR` during row policy expression analysis for correlated columns. [#82618](https://github.com/ClickHouse/ClickHouse/pull/82618) ([Dmitry Novik](https://github.com/novikd)).
* Backported in [#82735](https://github.com/ClickHouse/ClickHouse/issues/82735): Functions `trim{Left,Right,Both}` now support input strings of type "FixedString(N)". For example, `SELECT trimBoth(toFixedString('abc', 3), 'ac')` now works. [#82691](https://github.com/ClickHouse/ClickHouse/pull/82691) ([Robert Schulze](https://github.com/rschu1ze)).
* Backported in [#82800](https://github.com/ClickHouse/ClickHouse/issues/82800): Fix deserialization of `groupArraySample`/`groupArrayLast` in case of empty elements (deserialization could skip part of the binary if the input was empty, this can lead to corruption during data read and UNKNOWN_PACKET_FROM_SERVER in TCP protocol). This does not affect numbers and date time types. [#82763](https://github.com/ClickHouse/ClickHouse/pull/82763) ([Pedro Ferreira](https://github.com/PedroTadim)).

#### Build/Testing/Packaging Improvement
* Backported in [#82866](https://github.com/ClickHouse/ClickHouse/issues/82866): Use `libxml2` v2.14.4. [#82649](https://github.com/ClickHouse/ClickHouse/pull/82649) ([Konstantin Bogdanov](https://github.com/thevar1able)).

