ClickHouse/docs/changelogs/v20.10.6.27-stable.md

ClickHouse release v20.10.6.27-stable FIXME as compared to v20.10.5.10-stable

Performance Improvement

• Backported in #17591: Fix performance of reading from Merge tables over huge number of MergeTree tables. Fixes #7748. #16988 (Anton Popov).

Bug Fix

• Backported in #17157: Fixed uncontrolled growth of TDigest. #16680 (hrissan).
• Backported in #17314: Return number of affected rows for INSERT queries via MySQL protocol. Previously ClickHouse used to always return 0, it's fixed. Fixes #16605. #16715 (Winter Zhang).
• Backported in #17341: TODO. #16866 (Alexander Tokmakov).
• Backported in #17587: Fix optimization of group by with enabled setting optimize_aggregators_of_group_by_keys and joins. Fixes #12604. #16951 (Anton Popov).
• Backported in #17594: Fix order by optimization with monotonous functions. Fixes #16107. #16956 (Anton Popov).
• Backported in #17197: Avoid unnecessary network errors for remote queries which may be cancelled while execution, like queries with LIMIT. #17006 (Azat Khuzhin).
• Backported in #17431: Bug fix for funciton fuzzBits, related issue: #16980. #17051 (hexiaoting).
• Backported in #17130: Fixed crash on CREATE TABLE ... AS some_table query when some_table was created AS table_function() Fixes #16944. #17072 (Alexander Tokmakov).
• Backported in #17193: Fix ColumnConst comparison which leads to crash. This fixed #17088 . #17135 (Amos Bird).
• Backported in #17395: Fix #15235. When clickhouse-copier handle non-partitioned table, throws segfault error. #17248 (Qi Chen).
• Backported in #17407: Fix set index invalidation when there are const columns in the subquery. This fixes #17246 . #17249 (Amos Bird).
• Backported in #17487: Fix crash while reading from JOIN table with LowCardinality types. Fixes #17228. #17397 (Nikolai Kochetov).
• Backported in #17491: Fix duplicates after DISTINCT which were possible because of incorrect optimization. Fixes #17294. #17296 (li chengxiang). #17439 (Nikolai Kochetov).
• Backported in #17524: Fix ORDER BY with enabled setting optimize_redundant_functions_in_order_by. #17471 (Anton Popov).
• Backported in #17532: Fix bug when mark cache size was underestimated by clickhouse. It may happen when there are a lot of tiny files with marks. #17496 (alesapin).
• Backported in #17626: Fix alter query hang when the corresponding mutation was killed on the different replica. Fixes #16953. #17499 (alesapin).
• Backported in #17609: When clickhouse-client is used in interactive mode with multiline queries, single line comment was erronously extended till the end of query. This fixes #13654. #17565 (Alexey Milovidov).
• Backported in #17698: In might be determined incorrectly if cluster is circular- (cross-) replicated or not when executing ON CLUSTER query due to race condition when pool_size > 1. It's fixed. #17640 (Alexander Tokmakov).
• Backported in #17730: Fixed Function not implemented error when executing RENAME query in Atomic database with ClickHouse running on Windows Subsystem for Linux. Fixes #17661. #17664 (Alexander Tokmakov).
• Backported in #17783: Fixed problem when ClickHouse fails to resume connection to MySQL servers. #17681 (Alexander Kazakov).
• Backported in #17816: Do not restore parts from WAL if in_memory_parts_enable_wal is disabled. #17802 (detailyang).

Build/Testing/Packaging Improvement

• Backported in #17289: Update embedded timezone data to version 2020d (also update cctz to the latest master). #17204 (filimonov).