25.8.33.20001 Altinity Antalya

25.8.33.20001 Altinity Antalya (b65106c) as compared to v25.8.22.20001.altinityantalya (e1a7eb14c505eff84ec1dbf50b0a85c810ffc2f7)

Backward Incompatible Change

• ALTER MODIFY COLUMN now requires explicit DEFAULT when converting nullable columns to non-nullable types. Previously such ALTERs could get stuck with cannot convert null to not null errors, now NULLs are replaced with column's default expression (ClickHouse#84770 by @vdimir via #2169)

New Features

• Added new SQL statement EXECUTE AS to support user impersonation (ClickHouse#70775 by @shiyer7474, ClickHouse#90437 by @alexbakharew via #2165)

Performance Improvements

• Reduce INSERT/merges memory usage with wide parts for very wide tables by enabling adaptive write buffers. Add support of adaptive write buffers for encrypted disks (ClickHouse#92250 by @azat via #2166)

Improvements

• Add a dedicated cleanup thread for MergeTree to prevent cleanup delays under heavy merge load. This resolves ClickHouse#86181. The MergeTree cleanup logic was tightly coupled with the merge scheduler, which caused cleanup tasks to be delayed or completely blocked when the table was under heavy merge load. ReplicatedMergeTree already had a separate cleanup thread, so this change aligns MergeTree with that design. @azat You might be interested in this one. (ClickHouse#91574 via #2059)
• S3Queue auxiliary Zookeeper support using keeper_path setting from s3Queue (ClickHouse#95203 by @lesandie via #2115)
• Fixes handling of users with a dot in the name when added via config file (ClickHouse#86633 by @mkmkme via #2167)

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

• Fixed use_client_time_zone being ignored for DateTime/DateTime64 string literals interpreted on the server (asynchronous INSERT, SELECT literals). The client now propagates its local time zone as session_timezone when use_client_time_zone is enabled, so server-side parsing matches the synchronous INSERT path (ClickHouse#109051 by @groeneai). (ClickHouse#109051 by @groeneai via #2047)
• Fix logical error in a rare case when empty tuple is used with Map column. Closes ClickHouse#93784. (ClickHouse#93814 by @nihalzp via #2068)
• Allow positional arguments in distributed queries (ClickHouse#94359 by @simonmichal via #2070)
• Fix columns_substreams.txt corruption during column rename in some cases. Closes ClickHouse#102259 (ClickHouse#102689 by @Avogar via #2072)
• Fix aggregation of sparse columns when group_by_overflow_mode is set to any (ClickHouse#88440 by @korowa, ClickHouse#95301 by @mkmkme via #2077)
• Fix regression in (experimental) zero‑copy replication introduced by ClickHouse#94262 where shared parts could be deleted before other replicas finished fetching them (ClickHouse#95597 by @filimonov). (#2079 by @mkmkme)
• Fixes a bug where OPTIMIZE FINAL on row-combining engines could crash the server (ClickHouse#106929) (#2080 by @mkmkme)
• Fix a regression with the Gorilla codec when an explicitly specified size does not correspond to the data type size, and the buffer size is too small. In previous versions, it threw an exception on decompression. Closes ClickHouse#78253 (ClickHouse#96118 by @alexey-milovidov via #2081)
• Fixed parquet reader v3 incorrectly handling arrays that cross page boundaries. This happens e.g. for files written by Arrow without enabling page statistics or page index. Affects only columns of Array data type. Likely symptom is that one array every ~1 MB of data gets truncated. Before this fix, use this setting as workaround: input_format_parquet_use_native_reader_v3 = 0 (ClickHouse#94125 by @al13n321 via #2103)
• Disable additional_table_filters with parallel replicas and analyzer and w/o query plan serialization (ClickHouse#104296 by @azat via #2109)
• Fix "TOO_MANY_MARKS" error which could have happened after some ALTER queries for compact parts (ClickHouse#91980 by @alesapin via #2162)
• Possible crash/undefined behavior in IN function where primary key column types are different from IN function right side column types (ClickHouse#89367 by @ilejn via #2164)
• Fix crash in StorageDistributed when parsing malformed shard directory names (ClickHouse#90243 by @AVMusorin via #2168)
• Fixed move-to-prewhere optimization, which did not work in the presence of row policy (ClickHouse#87303 by @KochetovNicolai via #2171)
• Split part ranges by volume characteristics to enable TTL drop merges for cold volumes. After this patch, parts with a max TTL < now will be removed from cold storage. The algorithm will schedule only single part drops. (ClickHouse#90059 by @Michicosun via #2172)
• Fix logical error with join_use_nulls and multiple joins along with cross join (ClickHouse#91853 by @vdimir via #2190)
• Fixes an issue where currentDatabase() used as a hybrid table argument would cause an UNKNOWN_TABLE error on restart (#2285 by @mkmkme)

Build/Testing/Packaging Improvements

• Upgrade Ubuntu Docker image packages to apply available security fixes. (#1972 by @CarlosFelipeOR) (#2185 by @mkmkme)

Packages

Available for both AMD64 and Aarch64 from https://builds.altinity.cloud/#altinityantalya as either .deb, .rpm, or .tgz

Docker images

Available for both AMD64 and Aarch64: altinity/clickhouse-server:25.8.33.20001.altinityantalya

Full Changelog: e1a7eb1...b65106c