ClickHouse/docs/changelogs/v20.9.4.76-stable.md

ClickHouse release v20.9.4.76-stable FIXME as compared to v20.9.3.45-stable

Improvement

• Backported in #16145: Now it's allowed to execute ALTER ... ON CLUSTER queries regardless of the <internal_replication> setting in cluster config. #16075 (alesapin).
• Backported in #16312: Add allow_nondeterministic_optimize_skip_unused_shards (to allow non deterministic like rand() or dictGet() in sharding key). #16105 (Azat Khuzhin).

Bug Fix

• Backported in #15618: Throw an error when a single parameter is passed to ReplicatedMergeTree instead of ignoring it. #15516 (nvartolomei).
• Backported in #16201: Decrement the ReadonlyReplica metric when detaching read-only tables. This fixes #15598. #15592 (sundyli).
• Backported in #16229: Fixed bug with globs in S3 table function, region from URL was not applied to S3 client configuration. #15646 (Vladimir Chebotarev).
• Backported in #15870: Fix error Cannot add simple transform to empty Pipe which happened while reading from Buffer table which has different structure than destination table. It was possible if destination table returned empty result for query. Fixes #15529. #15662 (Nikolai Kochetov).
• Backported in #15774: Fixed too low default value of max_replicated_logs_to_keep setting, which might cause replicas to become lost too often. Improve lost replica recovery process by choosing the most up-to-date replica to clone. Also do not remove old parts from lost replica, detach them instead. #15701 (Alexander Tokmakov).
• Backported in #15798: Fix some cases of queries, in which only virtual columns are selected. Previously Not found column _nothing in block exception may be thrown. Fixes #12298. #15756 (Anton Popov).
• Backported in #15868: Fix select count() inaccuracy for MaterializeMySQL. #15767 (Alexander Tokmakov).
• Backported in #15901: Fix exception Block structure mismatch in SELECT ... ORDER BY DESC queries which were executed after ALTER MODIFY COLUMN query. Fixes #15800. #15852 (alesapin).
• Backported in #15924: Now exception will be thrown when ALTER MODIFY COLUMN ... DEFAULT ... has incompatible default with column type. Fixes #15854. #15858 (alesapin).
• Backported in #15919: Fix possible deadlocks in RBAC. #15875 (Vitaly Baranov).
• Backported in #16167: Fix incorrect empty result for query from Distributed table if query has WHERE, PREWHERE and GLOBAL IN. Fixes #15792. #15933 (Nikolai Kochetov).
• Backported in #16356: Fixed DROP TABLE IF EXISTS failure with Table ... doesn't exist error when table is concurrently renamed (for Atomic database engine). Fixed rare deadlock when concurrently executing some DDL queries with multiple tables (like DROP DATABASE and RENAME TABLE) Fixed DROP/DETACH DATABASE failure with Table ... doesn't exist when concurrently executing DROP/DETACH TABLE. #15934 (Alexander Tokmakov).
• Backported in #15971: Fix a crash when database creation fails. #15954 (Winter Zhang).
• Backported in #16022: Fix ambiguity in parsing of settings profiles: CREATE USER ... SETTINGS profile readonly is now considered as using a profile named readonly, not a setting named profile with the readonly constraint. This fixes #15628. #15982 (Vitaly Baranov).
• Backported in #16218: Fix rare segfaults when inserting into or selecting from MaterializedView and concurrently dropping target table (for Atomic database engine). #15984 (Alexander Tokmakov).
• Backported in #16026: Prevent replica hang for 5-10 mins when replication error happens after a period of inactivity. #15987 (filimonov).
• Backported in #16091: Allow to use direct layout for dictionaries with complex keys. #16007 (Anton Popov).
• Backported in #16361: Fix collate name & charset name parser and support length = 0 for string type. #16008 (Winter Zhang).
• Backported in #16140: Fix ALTER MODIFY ... ORDER BY query hang for ReplicatedVersionedCollapsingMergeTree. This fixes #15980. #16011 (alesapin).
• Backported in #16079: Fixes #15780 regression, e.g. indexOf([1, 2, 3], toLowCardinality(1)) now is prohibited but it should not be. #16038 (Mike Kot).
• Backported in #16298: Fix dictGet in sharding_key (and similar places, i.e. when the function context is stored permanently). #16205 (Azat Khuzhin).
• Backported in #16232: Fix the case when memory can be overallocated regardless to the limit. This closes #14560. #16206 (Alexey Milovidov).
• Backported in #16326: Fix a possible memory leak during GROUP BY with string keys, caused by an error in TwoLevelStringHashTable implementation. #16264 (Amos Bird).
• Backported in #16377: Fix async Distributed INSERT w/ prefer_localhost_replica=0 and internal_replication. #16358 (Azat Khuzhin).
• Backported in #16432: Fix group by with totals/rollup/cube modifers and min/max functions over group by keys. Fixes #16393. #16397 (Anton Popov).
• Backported in #16449: Fix double free in case of exception in function dictGet. It could have happened if dictionary was loaded with error. #16429 (Nikolai Kochetov).

Other

• Unfold {database}, {table} and {uuid} macros in ReplicatedMergeTree arguments on table creation. #16160 (Alexander Tokmakov).