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sidebar_position: 1
sidebar_label: 2025
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# 2025 Changelog

### ClickHouse release v25.2.2.39-stable (a1200cff50a) FIXME as compared to v25.2.1.3085-stable (09989205d6f)

#### Backward Incompatible Change
* Backported in [#77183](https://github.com/ClickHouse/ClickHouse/issues/77183): Disable parallel replicas by default when analyzer is disabled regardless `compatibility` setting. It's still possible to change this behavior by explicitly setting `parallel_replicas_only_with_analyzer` to `false`. [#77115](https://github.com/ClickHouse/ClickHouse/pull/77115) ([Igor Nikonov](https://github.com/devcrafter)).

#### New Feature
* Backported in [#77358](https://github.com/ClickHouse/ClickHouse/issues/77358): Added `concurrent_threads_scheduler` server setting that governs how CPU slots are distributed among concurrent queries. Could be set to `round_robin` (previous behavior) or `fair_round_robin` to address the issue of unfair CPU distribution between INSERTs and SELECTs. [#75949](https://github.com/ClickHouse/ClickHouse/pull/75949) ([Sergei Trifonov](https://github.com/serxa)).

#### Bug Fix (user-visible misbehavior in an official stable release)
* Backported in [#76999](https://github.com/ClickHouse/ClickHouse/issues/76999): Fix data loss when enable async insert and insert into ... from file ... with unequal block size if the first block size < async_max_size but the second block > async_max_size, the second block will not be inserted. these data is left in `squashing`. [#76343](https://github.com/ClickHouse/ClickHouse/pull/76343) ([Han Fei](https://github.com/hanfei1991)).
* Backported in [#76970](https://github.com/ClickHouse/ClickHouse/issues/76970): Fix THERE_IS_NO_COLUMN exception when selecting boolean literal from distributed tables. [#76656](https://github.com/ClickHouse/ClickHouse/pull/76656) ([Yakov Olkhovskiy](https://github.com/yakov-olkhovskiy)).
* Backported in [#77049](https://github.com/ClickHouse/ClickHouse/issues/77049): Fix exception handling in parallel prefixes deserialization of JSON subcolumns. [#76809](https://github.com/ClickHouse/ClickHouse/pull/76809) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#77260](https://github.com/ClickHouse/ClickHouse/issues/77260): Fix possible crash because of bad JSON column rollback on error during async inserts. [#76908](https://github.com/ClickHouse/ClickHouse/pull/76908) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#77064](https://github.com/ClickHouse/ClickHouse/issues/77064): Fix sorting of `BFloat16` values. This closes [#75487](https://github.com/ClickHouse/ClickHouse/issues/75487). This closes [#75669](https://github.com/ClickHouse/ClickHouse/issues/75669). [#77000](https://github.com/ClickHouse/ClickHouse/pull/77000) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
* Backported in [#77222](https://github.com/ClickHouse/ClickHouse/issues/77222): Bug fix json with variant subcolumn by adding check to skip ephemeral subcolumns in part consistency check. [#72187](https://github.com/ClickHouse/ClickHouse/issues/72187). [#77034](https://github.com/ClickHouse/ClickHouse/pull/77034) ([Smita Kulkarni](https://github.com/SmitaRKulkarni)).
* Backported in [#77250](https://github.com/ClickHouse/ClickHouse/issues/77250): Fix crash during Kafka table creation with exception. [#77121](https://github.com/ClickHouse/ClickHouse/pull/77121) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#77240](https://github.com/ClickHouse/ClickHouse/issues/77240): Support new JSON and subcolumns in Kafka and RabbitMQ engines. [#77122](https://github.com/ClickHouse/ClickHouse/pull/77122) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#77386](https://github.com/ClickHouse/ClickHouse/issues/77386): `SELECT toBFloat16(-0.0) == toBFloat16(0.0)` now correctly returns `true` (from previously `false`). This makes the behavior consistent with `Float32` and `Float64`. [#77290](https://github.com/ClickHouse/ClickHouse/pull/77290) ([Shankar Iyer](https://github.com/shankar-iyer)).
* Backported in [#77379](https://github.com/ClickHouse/ClickHouse/issues/77379): Fix name for partition with a Bool value. It was broken in https://github.com/ClickHouse/ClickHouse/pull/74533. [#77319](https://github.com/ClickHouse/ClickHouse/pull/77319) ([Pavel Kruglov](https://github.com/Avogar)).
* Backported in [#77335](https://github.com/ClickHouse/ClickHouse/issues/77335): Fix comparison between tuples with nullable elements inside and strings. [#77323](https://github.com/ClickHouse/ClickHouse/pull/77323) ([Alexey Katsman](https://github.com/alexkats)).

#### NOT FOR CHANGELOG / INSIGNIFICANT

* Backported in [#76961](https://github.com/ClickHouse/ClickHouse/issues/76961): Allow empty chunks in FinishSortingTransfrom. [#76919](https://github.com/ClickHouse/ClickHouse/pull/76919) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
* Backported in [#77047](https://github.com/ClickHouse/ClickHouse/issues/77047): fix fast test 02783_parsedatetimebesteffort leap year. [#76940](https://github.com/ClickHouse/ClickHouse/pull/76940) ([Han Fei](https://github.com/hanfei1991)).
* Backported in [#77084](https://github.com/ClickHouse/ClickHouse/issues/77084): Increase log level for dictionary loading. [#77052](https://github.com/ClickHouse/ClickHouse/pull/77052) ([Michael Lex](https://github.com/mlex)).
* Backported in [#77314](https://github.com/ClickHouse/ClickHouse/issues/77314): Fix uninitialized-value `CoordinationZnode::last_success_duration` in `RefreshTask`. [#77174](https://github.com/ClickHouse/ClickHouse/pull/77174) ([Tuan Pham Anh](https://github.com/tuanpach)).
* Backported in [#77536](https://github.com/ClickHouse/ClickHouse/issues/77536): Generate new certificates for test_reload_certificate. [#77495](https://github.com/ClickHouse/ClickHouse/pull/77495) ([Pervakov Grigorii](https://github.com/GrigoryPervakov)).

