2025 Changelog

ClickHouse release v25.9.7.56-stable (f805515dfb0) FIXME as compared to v25.9.6.117-stable (ff2a1965ca6)

Improvement

• Backported in #91250: Fixed potential thread pool starvation when reading column samples for JSON columns with many subcolumns by respecting the merge_tree_use_prefixes_deserialization_thread_pool setting instead of unconditionally using the thread pool. #91208 (Raufs Dunamalijevs).
• Backported in #92567: Make query memory usage detection for spilling to disk during aggregation/sorting more robust. #92500 (Azat Khuzhin).

Bug Fix (user-visible misbehavior in an official stable release)

• Backported in #92034: Fix GenerateRandom engine crash on non-literal parameters: return BAD_ARGUMENTS with a clear message instead of LOGICAL_ERROR. #88157 (Shafi Ahmed).
• Backported in #92185: Fix removing unused projection columns in the presence of UNION. Fixes #88180. #88350 (Sema Checherinda).
• Backported in #92221: Fix handling of non materialized Nested(Tuple(...)) (added via ALTER). Fixes #83133. #88879 (Azat Khuzhin).
• Backported in #90444: Fix inference of bad DateTime64 values from Strings in text formats in some cases. Resolves #89368. #90013 (Pavel Kruglov).
• Backported in #90756: Fix some queries with aggregated projection optimization. #90288 (János Benjamin Antal).
• Backported in #90912: Fix bug in reading subcolumns from JSON in compact parts that could lead to CANNOT_READ_ALL_DATA error. Resolves #90264. #90302 (Pavel Kruglov).
• Backported in #90973: Fix possible logical error during renaming and modifying the same Nested column in one ALTER. Resolves #90406. #90412 (Pavel Kruglov).
• Backported in #91055: Fix parsing JSON/Dynamic/Variant values from HTTP parameters. Resolves #88925. #90430 (Pavel Kruglov).
• Backported in #91872: Fixes a bug where toDateTimeOrNull of a negative argument returns NULL. #90490 (Yarik Briukhovetskyi).
• Backported in #91035: Fix possible logical error during output of LowCardinality(Bool/Date32) in Arrow format. Resolves #83883. #90505 (Pavel Kruglov).
• Backported in #90788: Retry to markReplicasActive when failing to resolve address during local host check: Print a warning log if there is an exception during self host check in DDLTask. In DDLWorker::markReplicasActive, throw an exception to retry if there is no local host found and there are host IDs in clusters. #90556 (Tuan Pham Anh).
• Backported in #91719: Fix type-casting errors when using LowCardinality columns in partition keys. Closes #89412. #90666 (xiaohuanlin).
• Backported in #90871: Fix named collections hidden secrets to depend on display_secrets_in_show_and_select and format_display_secrets_in_show_and_select. #90765 (Pablo Marcos).
• Backported in #90852: Fix possible inconsistent state of shared data and dynamic paths in JSON that could lead to logical errors and unexpected results. #90816 (Pavel Kruglov).
• Backported in #91321: Fix compatibility of in-memory serialization of String aggregation state. Different serialization could lead to duplicate results if aggregation query is executed on instances with different versions. New serialization can be enabled with serialize_string_in_memory_with_zero_byte. #90880 (Antonio Andelic).
• Backported in #90933: Fix background flush of Buffer in case of frequent INSERTs. #90892 (Azat Khuzhin).
• Backported in #91046: Fix high memory usage during reading JSON/Dynamic/Variant columns. #90907 (Pavel Kruglov).
• Backported in #91294: Fix buffer allocation for base58Decode function. #90909 (Antonio Andelic).
• Backported in #91221: Fix wildcard grants check for partial revoke. Added more tests. #90922 (pufit).
• Backported in #91500: Fixes SummingMergeTree aggregation for Nested LowCardinality columns. #90927 (Ivan Babrou).
• Backported in #91767: Fix handling global grants with wildcard revokes Fixes the issue when revoking a wildcard grant can accidentally revoke some global-level grants like CREATE USER. #90928 (pufit).
• Backported in #91079: Fix possible infinite loop in azure list blobs. #90947 (Julia Kartseva).
• Backported in #91137: Fix excessive Buffer flushes (burns CPU and produce tons of logs). #91000 (Azat Khuzhin).
• Backported in #91073: Fix bug in JSON when path can be both in shared data and dynamic paths during sub-object reading in Compact parts with disabled write_marks_for_substreams_in_compact_parts. #91014 (Pavel Kruglov).
• Backported in #91690: Fix reading dynamic subcolumns from materialized columns in mutations. Closes #90653. #91040 (Pavel Kruglov).
• Backported in #91347: Fix lazy materialization of a column added via alter add column in old parts. #91142 (Pavel Kruglov).
• Backported in #91265: Fix merging JSON columns in Summing/Aggregating/Coalescing MergeTree. Previously it could lead to unexpected dynamic paths durign writing to data parts. #91151 (Pavel Kruglov).
• Backported in #91318: Fix possible inconsistent dynamic structure during writing in compact parts that could lead to segfault. #91152 (Pavel Kruglov).
• Backported in #91401: Fix inserting into CoalescingMergeTree column with Tuple of JSON/Dynamic and LowCardinality. Closes #91215. #91270 (Pavel Kruglov).
• Backported in #91338: Fix SYSTEM DROP FILESYSTEM CACHE ON CLUSTER. #91304 (Anton Ivashkin).
• Backported in #91562: Currently, the setting is set to false, so when async insert queue is flushed to a remote server, the inserts are always synchronous. Even in case of the setting is True for a user. #91386 (Mikhail f. Shiryaev).
• Backported in #91458: Remove Sparse columns from header in merge algorithms. Closes #91377. #91396 (Pavel Kruglov).
• Backported in #92135: Fix crash in dictGetDescendants caused by NULL when dictionary type has Hierarchy support but no column is HIERARCHICAL. Closes #92026. Closes #92121. #91420 (Nihal Z. Miaji).
• Backported in #91799: Fix logical error caused by asterisks argument in remote function. Closes #90568. #91524 (Nihal Z. Miaji).
• Backported in #91680: Disallow ALTERs for Object Storage table engines. For example, ALTER ADD PROJECTION could have led to an inability to restart the server, since Object Storage engines do not support projections. #91573 (Nikolay Degterinsky).
• Backported in #91882: Fix increased memory usage in join with "additional filter", close #91011. #91664 (Vladimir Cherkasov).
• Backported in #91917: Fix LOGICAL_ERROR in RecursiveCTEChunkGenerator. #91827 (Pablo Marcos).
• Backported in #92242: Fix UDF replace in format. #92210 (Raúl Marín).
• Backported in #92330: In ddlworker::markreplicasactive, if there is no active host found, and the remote_servers has some host_ids, we print a warning log instead of throwing an exception. #92223 (Tuan Pham Anh).
• Backported in #92436: Fix logical error caused by using Nothing type in caseWithExpression function arguments . Closes #85354. #92351 (Nihal Z. Miaji).

Build/Testing/Packaging Improvement

• Backported in #91369: Bump libssh from 0.9.8 to master (0.11.3). This resolves https://github.com/advisories/GHSA-98qw-prqm-9f4p. #90985 (Govind R Nair).
• Backported in #92017: Fix flaky 00906_low_cardinality_cache. #92009 (Nikita Fomichev).
• Backported in #92467: Use any of chcache and sccache as rust wrapper. #92404 (Mikhail f. Shiryaev).

NOT FOR CHANGELOG / INSIGNIFICANT

• Backported in #90918: Make a separate IColumn method to take exact dynamic structure from a column. #87582 (Pavel Kruglov).
• Backported in #91516: This closes #87619. #87895 (Konstantin Vedernikov).
• Backported in #92508: CI: Fix clickhouse version tweak calculation for the fork with sync. #89098 (Max Kainov).
• Backported in #91731: CI: Fix tweak calculation in legacy version helper. #90950 (Max Kainov).
• Backported in #91150: Fix CI (due to tmpfs permissions changes in runc 1.3.3). #91094 (Azat Khuzhin).
• Backported in #91424: Add assertion for having empty metadata_files. #91210 (Daniil Ivanik).
• Backported in #91701: explicit POCO request for REST-polaris catalog. #91437 (Konstantin Vedernikov).
• Backported in #91952: Backport of the fix for optimize_skip_unused_shards optimization for Distributed engine that may lead to Serialization is not implemented for data type Set due to wrong types. #91923 (Azat Khuzhin).
• Backported in #91971: Backport fix 03644_object_storage_correlated_subqueries to release br…. #91957 (Vladimir Cherkasov).
• CI: Rebuild with fixed version. #92544 (Max Kainov).