2025 Changelog

- Basic support for the PromQL dialect is added. To use it, set `dialect='promql'` in clickhouse-client, point it to the TimeSeries table using the setting `promql_table_name='X'` and execute queries like `rate(ClickHouseProfileEvents_ReadCompressedBytes[1m])[5m:1m]`. In addition you can wrap the PromQL query with SQL: `SELECT * FROM prometheusQuery('up', ...);`. So far only functions `rate`, `delta` and `increase` are supported. No unary/binary operators. No HTTP API. [#75036](https://github.com/ClickHouse/ClickHouse/pull/75036) ([Vitaly Baranov](https://github.com/vitlibar)).
- AI Powered SQL generation can now infer from env ANTHROPIC\_API\_KEY and OPENAI\_API\_KEY if available, this is to make it so that we can have a zero config option to use this feature. [#83787](https://github.com/ClickHouse/ClickHouse/pull/83787) ([Kaushik Iska](https://github.com/iskakaushik)).
- Implement support for [ArrowFlight RPC](https://arrow.apache.org/docs/format/Flight.html) protocol by adding: - new table function `arrowflight`. [#74184](https://github.com/ClickHouse/ClickHouse/pull/74184) ([zakr600](https://github.com/zakr600)).
- Now all tables support the `_table` virtual column (not only tables with the `Merge` engine), which is especially useful for queries with UNION ALL. [#63665](https://github.com/ClickHouse/ClickHouse/pull/63665) ([Xiaozhe Yu](https://github.com/wudidapaopao)).
- Allow to use any storage policy (i.e. object storage, such as S3) for external aggregation/sorting. [#84734](https://github.com/ClickHouse/ClickHouse/pull/84734) ([Azat Khuzhin](https://github.com/azat)).
- Implement AWS S3 authentication with an explicitly provided IAM role. Implement OAuth for GCS. These features were recently only available in ClickHouse Cloud and are now open-sourced. Synchronize some interfaces such as serialization of the connection parameters for object storages. [#84011](https://github.com/ClickHouse/ClickHouse/pull/84011) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Support position deletes for Iceberg TableEngine. [#83094](https://github.com/ClickHouse/ClickHouse/pull/83094) ([Daniil Ivanik](https://github.com/divanik)).
- Support Iceberg Equality Deletes. [#85843](https://github.com/ClickHouse/ClickHouse/pull/85843) ([Han Fei](https://github.com/hanfei1991)).
- Iceberg writes for create. Closes [#83927](https://github.com/ClickHouse/ClickHouse/issues/83927). [#83983](https://github.com/ClickHouse/ClickHouse/pull/83983) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Glue catalogs for writes. [#84136](https://github.com/ClickHouse/ClickHouse/pull/84136) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Iceberg Rest catalogs for writes. [#84684](https://github.com/ClickHouse/ClickHouse/pull/84684) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Merge all iceberg position delete files into data files. This will reduce amount and sizes of parquet files in iceberg storage. Syntax: `OPTIMIZE TABLE table_name`. [#85250](https://github.com/ClickHouse/ClickHouse/pull/85250) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Support `drop table` for iceberg (Removing from REST/Glue catalogs + removing metadata about table). [#85395](https://github.com/ClickHouse/ClickHouse/pull/85395) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Support alter delete mutations for iceberg in merge-on-read format. [#85549](https://github.com/ClickHouse/ClickHouse/pull/85549) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Support writes into DeltaLake. Closes [#79603](https://github.com/ClickHouse/ClickHouse/issues/79603). [#85564](https://github.com/ClickHouse/ClickHouse/pull/85564) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Added setting `delta_lake_snapshot_version` to allow reading specific snapshot version in table engine `DeltaLake`. [#85295](https://github.com/ClickHouse/ClickHouse/pull/85295) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Write more iceberg statistics (column sizes, lower and upper bounds) in metadata (manifest entries) for min-max pruning. [#85746](https://github.com/ClickHouse/ClickHouse/pull/85746) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Support add/drop/modify columns in iceberg for simple types. [#85769](https://github.com/ClickHouse/ClickHouse/pull/85769) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Iceberg: support writing version-hint file. This closes [#85097](https://github.com/ClickHouse/ClickHouse/issues/85097). [#85130](https://github.com/ClickHouse/ClickHouse/pull/85130) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Views, created by ephemeral users, will now store a copy of an actual user and will no longer be invalidated after the ephemeral user is deleted. [#84763](https://github.com/ClickHouse/ClickHouse/pull/84763) ([pufit](https://github.com/pufit)).
- The vector similarity index now supports binary quantization. Binary quantization significantly reduces the memory consumption and speeds up the process of building a vector index (due to faster distance calculation). Also, the existing setting `vector_search_postfilter_multiplier` was made obsolete and replaced by a more general setting : `vector_search_index_fetch_multiplier`. [#85024](https://github.com/ClickHouse/ClickHouse/pull/85024) ([Shankar Iyer](https://github.com/shankar-iyer)).
- Allow key value arguments in `s3` or `s3Cluster` table engine/function, e.g. for example `s3('url', CSV, structure = 'a Int32', compression_method = 'gzip')`. [#85134](https://github.com/ClickHouse/ClickHouse/pull/85134) ([Kseniia Sumarokova](https://github.com/kssenii)).
- A new system table to keep erroneous incoming messages from engines like kafka ("dead letter queue"). [#68873](https://github.com/ClickHouse/ClickHouse/pull/68873) ([Ilya Golshtein](https://github.com/ilejn)).
- The new SYSTEM RESTORE DATABASE REPLICA for Replicated databases, similar to the existing functionality for restore in ReplicatedMergeTree. [#73100](https://github.com/ClickHouse/ClickHouse/pull/73100) ([Konstantin Morozov](https://github.com/k-morozov)).
- PostgreSQL protocol now supports the `COPY` command. [#74344](https://github.com/ClickHouse/ClickHouse/pull/74344) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Support C# client for mysql protocol. This closes [#83992](https://github.com/ClickHouse/ClickHouse/issues/83992). [#84397](https://github.com/ClickHouse/ClickHouse/pull/84397) ([Konstantin Vedernikov](https://github.com/scanhex12)).
- Add support for hive partition style reads and writes. [#76802](https://github.com/ClickHouse/ClickHouse/pull/76802) ([Arthur Passos](https://github.com/arthurpassos)).
- Add `zookeeper_connection_log` system table to store historical information about ZooKeeper connections. [#79494](https://github.com/ClickHouse/ClickHouse/pull/79494) ([János Benjamin Antal](https://github.com/antaljanosbenjamin)).
- Server setting `cpu_slot_preemption` enables preemptive CPU scheduling for workloads and ensures max-min fair allocation of CPU time among workloads. New workload settings for CPU throttling are added: `max_cpus`, `max_cpu_share` and `max_burst_cpu_seconds`. More details: <https://clickhouse.com/docs/operations/workload-scheduling#cpu_scheduling>. [#80879](https://github.com/ClickHouse/ClickHouse/pull/80879) ([Sergei Trifonov](https://github.com/serxa)).
- Drop TCP connection after a configured number of queries or time threshold. This makes sense for a more uniform connection distribution between cluster nodes behind a load balancer. Resolves [#68000](https://github.com/ClickHouse/ClickHouse/issues/68000). [#81472](https://github.com/ClickHouse/ClickHouse/pull/81472) ([Kenny Sun](https://github.com/hwabis)).
- Parallel replicas now support using projections for queries. [#82659](https://github.com/ClickHouse/ClickHouse/issues/82659). [#82807](https://github.com/ClickHouse/ClickHouse/pull/82807) ([zoomxi](https://github.com/zoomxi)).
- Support DESCRIBE SELECT in addition to DESCRIBE (SELECT ...). [#82947](https://github.com/ClickHouse/ClickHouse/pull/82947) ([Yarik Briukhovetskyi](https://github.com/yariks5s)).