ClickHouse/docs/changelogs/v20.6.8.5-stable.md

ClickHouse release v20.6.8.5-stable FIXME as compared to v20.6.7.4-stable

Improvement

• Backported in #15567: Now it's possible to change the type of version column for VersionedCollapsingMergeTree with ALTER query. #15442 (alesapin).

Bug Fix

• Backported in #15018: Fixed the incorrect sorting order of Nullable column. This fixes #14344. #14495 (Nikita Mikhaylov).
• Backported in #14826: Fix wrong monotonicity detection for shrunk Int -> Int cast of signed types. It might lead to incorrect query result. This bug is unveiled in #14513. #14783 (Amos Bird).
• Backported in #15147: Fix a problem where the server may get stuck on startup while talking to ZooKeeper, if the configuration files have to be fetched from ZK (using the from_zk include option). This fixes #14814. #14843 (Alexander Kuzmenkov).
• Backported in #15253: Fixed segfault in CacheDictionary #14837. #14879 (Nikita Mikhaylov).
• Backported in #14986: Publish CPU frequencies per logical core in system.asynchronous_metrics. This fixes #14923. #14924 (Alexander Kuzmenkov).
• Backported in #14968: Fix to make predicate push down work when subquery contains finalizeAggregation function. Fixes #14847. #14937 (filimonov).
• Backported in #15080: Fix crash in RIGHT or FULL JOIN with join_algorith='auto' when memory limit exceeded and we should change HashJoin with MergeJoin. #15002 (Artem Zuikov).
• Backported in #15057: If function bar was called with specifically crafted arguments, buffer overflow was possible. This closes #13926. #15028 (Alexey Milovidov).
• Backported in #15050: We already use padded comparison between String and FixedString (https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/FunctionsComparison.h#L333). This PR applies the same logic to field comparison which corrects the usage of FixedString as primary keys. This fixes #14908. #15033 (Amos Bird).
• Backported in #15143: Fixes Data compressed with different methods in join_algorithm='auto'. Keep LowCardinality as type for left table join key in join_algorithm='partial_merge'. #15088 (Artem Zuikov).
• Backported in #15223: Fix bug in table engine Buffer which doesn't allow to insert data of new structure into Buffer after ALTER query. Fixes #15117. #15192 (alesapin).
• Backported in #15404: Fix instance crash when using joinGet with LowCardinality types. This fixes #15214. #15220 (Amos Bird).
• Backported in #15279: Fix MSan report in QueryLog. Uninitialized memory can be used for the field memory_usage. #15258 (Alexey Milovidov).
• Backported in #15412: Fix hang of queries with a lot of subqueries to same table of MySQL engine. Previously, if there were more than 16 subqueries to same MySQL table in query, it hang forever. #15299 (Anton Popov).
• Backported in #15339: Fix rare race condition on server startup when system.logs are enabled. #15300 (alesapin).
• Backported in #15335: Fix race condition during MergeTree table rename and background cleanup. #15304 (alesapin).
• Backported in #15445: Report proper error when the second argument of boundingRatio aggregate function has a wrong type. #15407 (detailyang).
• Backported in #15508: Fix bug with event subscription in DDLWorker which rarely may lead to query hangs in ON CLUSTER. Introduced in #13450. #15477 (alesapin).
• Backported in #15616: Fix Missing columns errors when selecting columns which absent in data, but depend on other columns which also absent in data. Fixes #15530. #15532 (alesapin).
• Backported in #15561: Fix bug when ILIKE operator stops being case insensitive if LIKE with the same pattern was executed. #15536 (alesapin).
• Backported in #15728: Mutation might hang waiting for some non-existent part after MOVE or REPLACE PARTITION or, in rare cases, after DETACH or DROP PARTITION. It's fixed. #15537 (Alexander Tokmakov).
• Backported in #15654: Fix 'Database doesn't exist.' in queries with IN and Distributed table when there's no database on initiator. #15538 (Artem Zuikov).
• Backported in #15586: Prevent the possibility of error message Could not calculate available disk space (statvfs), errno: 4, strerror: Interrupted system call. This fixes #15541. #15557 (Alexey Milovidov).
• Backported in #15664: Fixed Element ... is not a constant expression error when using JSON* function result in VALUES, LIMIT or right side of IN operator. #15589 (Alexander Tokmakov).
• Backported in #15714: Fix the order of destruction for resources in ReadFromStorage step of query plan. It might cause crashes in rare cases. Possibly connected with #15610. #15645 (Nikolai Kochetov).