2025 Changelog

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-9 "Direct link to Build/Testing/Packaging Improvement")

- `clickhouse-odbc-bridge` and `clickhouse-library-bridge` are moved to a separate repository, <https://github.com/ClickHouse/odbc-bridge/>. [#76225](https://github.com/ClickHouse/ClickHouse/pull/76225) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix Rust cross-compilation and allow disabling Rust completely. [#76921](https://github.com/ClickHouse/ClickHouse/pull/76921) ([Raúl Marín](https://github.com/Algunenano)).

### ClickHouse release 25.2, 2025-02-27[​](#252 "Direct link to ClickHouse release 25.2, 2025-02-27")

#### Backward Incompatible Change[​](#backward-incompatible-change-10 "Direct link to Backward Incompatible Change")

- Completely enable `async_load_databases` by default (even for those installations that do not upgrade `config.xml`). [#74772](https://github.com/ClickHouse/ClickHouse/pull/74772) ([Azat Khuzhin](https://github.com/azat)).
- Add `JSONCompactEachRowWithProgress` and `JSONCompactStringsEachRowWithProgress` formats. Continuation of [#69989](https://github.com/ClickHouse/ClickHouse/issues/69989). The `JSONCompactWithNames` and `JSONCompactWithNamesAndTypes` no longer output "totals" - apparently, it was a mistake in the implementation. [#75037](https://github.com/ClickHouse/ClickHouse/pull/75037) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Change the `format_alter_operations_with_parentheses` default to true to disambiguate the ALTER commands list (see <https://github.com/ClickHouse/ClickHouse/pull/59532>). This breaks replication with clusters prior to 24.3. If you are upgrading a cluster using older releases turn off the setting in the server config or upgrade to 24.3 first. [#75302](https://github.com/ClickHouse/ClickHouse/pull/75302) ([Raúl Marín](https://github.com/Algunenano)).
- Remove the possibility of filtering log messages using regular expressions. The implementation introduced a data race, so it has to be removed. [#75577](https://github.com/ClickHouse/ClickHouse/pull/75577) ([János Benjamin Antal](https://github.com/antaljanosbenjamin)).
- The setting `min_chunk_bytes_for_parallel_parsing` cannot be zero anymore. This fixes: [#71110](https://github.com/ClickHouse/ClickHouse/issues/71110). [#75239](https://github.com/ClickHouse/ClickHouse/pull/75239) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- Validate settings in the cache configuration. Non existing settings were ignored before, now they will throw an error and they should be removed. [#75452](https://github.com/ClickHouse/ClickHouse/pull/75452) ([Kseniia Sumarokova](https://github.com/kssenii)).

#### New Feature[​](#new-feature-10 "Direct link to New Feature")

- Support type `Nullable(JSON)`. [#73556](https://github.com/ClickHouse/ClickHouse/pull/73556) ([Pavel Kruglov](https://github.com/Avogar)).
- Support subcolumns in the DEFAULT and MATERIALIZED expressions. [#74403](https://github.com/ClickHouse/ClickHouse/pull/74403) ([Pavel Kruglov](https://github.com/Avogar)).
- Support writing Parquet bloom filters using the `output_format_parquet_write_bloom_filter` setting (enabled by default). [#71681](https://github.com/ClickHouse/ClickHouse/pull/71681) ([Michael Kolupaev](https://github.com/al13n321)).
- Web UI now has interactive database navigation. [#75777](https://github.com/ClickHouse/ClickHouse/pull/75777) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Allow the combination of read-only and read-write disks in the storage policy (as multiple volumes or multiple disks). This allows data to be read from the entire volume, while inserts will prefer the writable disk (i.e., Copy-on-Write storage policy). [#75862](https://github.com/ClickHouse/ClickHouse/pull/75862) ([Azat Khuzhin](https://github.com/azat)).
- Add a new Database engine, `DatabaseBackup,` that allows to instantly attach table/database from backup. [#75725](https://github.com/ClickHouse/ClickHouse/pull/75725) ([Maksim Kita](https://github.com/kitaisreal)).
- Support prepared statements in the Postgres wire protocol. [#75035](https://github.com/ClickHouse/ClickHouse/pull/75035) ([scanhex12](https://github.com/scanhex12)).
- Add the ability to ATTACH tables without a database layer, which is useful for MergeTree tables located on Web, S3, and similar external virtual filesystems. [#75788](https://github.com/ClickHouse/ClickHouse/pull/75788) ([Azat Khuzhin](https://github.com/azat)).
- Add a new string comparison function, `compareSubstrings` to compare parts of two strings. Example: `SELECT compareSubstrings('Saxony', 'Anglo-Saxon', 0, 6, 5) AS result` means "compare 6 bytes of strings 'Saxon' and 'Anglo-Saxon' lexicographically, starting at offset 0 in the first string, offset 5 in the second string". [#74070](https://github.com/ClickHouse/ClickHouse/pull/74070) ([lgbo](https://github.com/lgbo-ustc)).
- A new function, `initialQueryStartTime` is added. It returns the start time of the current query. The value is the same across all shards during a distributed query. [#75087](https://github.com/ClickHouse/ClickHouse/pull/75087) ([Roman Lomonosov](https://github.com/lomik)).
- Add support for SSL authentication with named collections for MySQL. Closes [#59111](https://github.com/ClickHouse/ClickHouse/issues/59111). [#59452](https://github.com/ClickHouse/ClickHouse/pull/59452) ([Nikolay Degterinsky](https://github.com/evillique)).

#### Experimental Features[​](#experimental-features "Direct link to Experimental Features")

- Added a new setting, `enable_adaptive_memory_spill_scheduler` that allows multiple Grace JOINs in the same query to monitor their combined memory footprint and trigger spilling into external storage adaptively to prevent MEMORY\_LIMIT\_EXCEEDED. [#72728](https://github.com/ClickHouse/ClickHouse/pull/72728) ([lgbo](https://github.com/lgbo-ustc)).
- Make the new, experimental `Kafka` table engine fully respect Keeper feature flags. [#76004](https://github.com/ClickHouse/ClickHouse/pull/76004) ([János Benjamin Antal](https://github.com/antaljanosbenjamin)).
- Restore the (Intel) QPL codec, which was removed in v24.10 due to licensing issues. [#76021](https://github.com/ClickHouse/ClickHouse/pull/76021) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- For the integration with HDFS added support for the `dfs.client.use.datanode.hostname` configuration option. [#74635](https://github.com/ClickHouse/ClickHouse/pull/74635) ([Mikhail Tiukavkin](https://github.com/freshertm)).

#### Performance Improvement[​](#performance-improvement-10 "Direct link to Performance Improvement")