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sidebar_position: 1
sidebar_label: 2025
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# 2025 Changelog

### ClickHouse release v25.4.2.31-stable (e2ce00b6885) FIXME as compared to v25.4.1.2934-stable (589918f385f)

#### Performance Improvement
* Backported in [#79662](https://github.com/ClickHouse/ClickHouse/issues/79662): Introduced threshold (regulated by setting `parallel_hash_join_threshold`) to fall back to the `hash` algorithm when the size of the right table is below the threshold. [#76185](https://github.com/ClickHouse/ClickHouse/pull/76185) ([Nikita Taranov](https://github.com/nickitat)).
* Backported in [#79728](https://github.com/ClickHouse/ClickHouse/issues/79728): Fix performance of the distributed INSERT SELECT with parallel replicas. [#79441](https://github.com/ClickHouse/ClickHouse/pull/79441) ([Azat Khuzhin](https://github.com/azat)).

#### Improvement
* Backported in [#79479](https://github.com/ClickHouse/ClickHouse/issues/79479): Fix possible endless loop when listing blobs from Azure/S3 blob storage. [#79425](https://github.com/ClickHouse/ClickHouse/pull/79425) ([Alexander Gololobov](https://github.com/davenger)).

#### Bug Fix (user-visible misbehavior in an official stable release)
* Backported in [#79502](https://github.com/ClickHouse/ClickHouse/issues/79502): ```sql CREATE TABLE t0 ( key Int32, value Int32 ) ENGINE=MergeTree() PRIMARY KEY key PARTITION BY key % 2;. [#78593](https://github.com/ClickHouse/ClickHouse/pull/78593) ([Vlad](https://github.com/codeworse)).
* Backported in [#79435](https://github.com/ClickHouse/ClickHouse/issues/79435): Fixes a bug where arrayUnion() returned extra (incorrect) values on tables that had batch inserts. Fixes [#79157](https://github.com/ClickHouse/ClickHouse/issues/79157). [#79158](https://github.com/ClickHouse/ClickHouse/pull/79158) ([Peter Nguyen](https://github.com/petern48)).
* Backported in [#79607](https://github.com/ClickHouse/ClickHouse/issues/79607): Fix loading of plain_rewritable disks containing data. [#79439](https://github.com/ClickHouse/ClickHouse/pull/79439) ([Julia Kartseva](https://github.com/jkartseva)).
* Backported in [#79525](https://github.com/ClickHouse/ClickHouse/issues/79525): Fixed error `Block structure mismatch` in several cases with tables with sparse columns. [#79491](https://github.com/ClickHouse/ClickHouse/pull/79491) ([Anton Popov](https://github.com/CurtizJ)).
* Backported in [#79616](https://github.com/ClickHouse/ClickHouse/issues/79616): Fix result duplication when reading from remote with both `use_hedged_requests` and `allow_experimental_parallel_reading_from_replicas` disabled. [#79599](https://github.com/ClickHouse/ClickHouse/pull/79599) ([Eduard Karacharov](https://github.com/korowa)).

#### NOT FOR CHANGELOG / INSIGNIFICANT

* Backported in [#79694](https://github.com/ClickHouse/ClickHouse/issues/79694): Lazy Materialization with parallel replicas. [#79401](https://github.com/ClickHouse/ClickHouse/pull/79401) ([Igor Nikonov](https://github.com/devcrafter)).
* Backported in [#79580](https://github.com/ClickHouse/ClickHouse/issues/79580): Fix a typo in threadstack::getsize. [#79533](https://github.com/ClickHouse/ClickHouse/pull/79533) ([Sema Checherinda](https://github.com/CheSema)).
* Backported in [#79595](https://github.com/ClickHouse/ClickHouse/issues/79595): fix data race in poco::JSON::stringify. [#79574](https://github.com/ClickHouse/ClickHouse/pull/79574) ([Han Fei](https://github.com/hanfei1991)).
* Backported in [#79686](https://github.com/ClickHouse/ClickHouse/issues/79686): Make [#76185](https://github.com/ClickHouse/ClickHouse/issues/76185) backportable. [#79665](https://github.com/ClickHouse/ClickHouse/pull/79665) ([Nikita Taranov](https://github.com/nickitat)).
* Backported in [#79705](https://github.com/ClickHouse/ClickHouse/issues/79705): refine the exception message when keeper reaches soft memory limit. [#79670](https://github.com/ClickHouse/ClickHouse/pull/79670) ([Han Fei](https://github.com/hanfei1991)).
* Backport test_storage_rabbitmq/test_failed_connection from master into 25.4. [#79713](https://github.com/ClickHouse/ClickHouse/pull/79713) ([Pablo Marcos](https://github.com/pamarcos)).

