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sidebar_position: 1
sidebar_label: 2025
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# 2025 Changelog

### ClickHouse release v25.5.8.13-stable (b594fb9739e) FIXME as compared to v25.5.7.52-stable (6e66ab95d8a)

#### Bug Fix (user-visible misbehavior in an official stable release)
* Backported in [#83209](https://github.com/ClickHouse/ClickHouse/issues/83209): Fix performance degradation in SummingMergeTree that was intorduced in 25.5 in https://github.com/ClickHouse/ClickHouse/pull/79051. [#82130](https://github.com/ClickHouse/ClickHouse/pull/82130) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#83199](https://github.com/ClickHouse/ClickHouse/issues/83199): Do not check for cyclic dependencies on create table with no dependencies. It fixes performance degradation of the use cases with creation of thousands of tables that was introduced in https://github.com/ClickHouse/ClickHouse/pull/65405. [#83077](https://github.com/ClickHouse/ClickHouse/pull/83077) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#83473](https://github.com/ClickHouse/ClickHouse/issues/83473): Fix possible crash in Variant type in UNION. [#83295](https://github.com/ClickHouse/ClickHouse/pull/83295) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#83764](https://github.com/ClickHouse/ClickHouse/issues/83764): Keeper fix: update total watch count correctly when ephemeral nodes are deleted on session close. [#83583](https://github.com/ClickHouse/ClickHouse/pull/83583) ([Antonio Andelic](https://github.com/antonio2368)).

#### NOT FOR CHANGELOG / INSIGNIFICANT

* Backported in [#83813](https://github.com/ClickHouse/ClickHouse/issues/83813): hold the temporary part lock when executeReplaceRange. [#83095](https://github.com/ClickHouse/ClickHouse/pull/83095) ([Sema Checherinda](https://github.com/CheSema)).
* Backported in [#83864](https://github.com/ClickHouse/ClickHouse/issues/83864): Allow concurrent tables creation when `max_database_replicated_create_table_thread_pool_size` setting is 0 (automatic pool size). [#83834](https://github.com/ClickHouse/ClickHouse/pull/83834) ([Alexander Tokmakov](https://github.com/tavplubix)).

